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Products => Test Equipment => Topic started by: marshallh on June 11, 2013, 09:43:38 pm

Title: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on June 11, 2013, 09:43:38 pm
(http://imageshack.us/a/img18/5233/img1024gx.jpg)


This series was designed in 1998-1999 by japanese test equipment firm Advantest. The RF input and a couple things were revised for the A revision a few years later.
The A revision increases the maximum input power from 20dBm to 30dBm.




(http://imageshack.us/a/img801/6760/img1020gx.jpg)


Using my Lecroy scope to generate a 2mhz square wave. At this point it passes all test except IF Step Amp when not fully warmed up.
After about 40mins of running time self test indicates TOTAL GAIN errors (this is measured through both the RF and IF boards)





(http://imageshack.us/a/img18/8326/img1025ld.jpg)


Rear view in the card cage. From top to bottom:
CPU, A/D
IF/LOG
RF



(http://imageshack.us/a/img801/6562/img1029up.jpg)


CPU and analog acquisition board.

Main CPU is a Motorola 68306 (basically a 68EC000 with a bunch of extra i/o crap, DRAM controller and no FPU)
Can't be assed to figure out how much RAM, not important. Probably 128K or something around there.

1Mbyte NOR flash mfg by Fujitsu (that's the tsop48)
Interesting that the CPU is after the Freescale split (2006 date code) and there's micron DRAM from 1998! Had to be fun sourcing parts for this in 2007.
Not shown is the floppy drive.

A couple custom ADVANTEST asics (which as far as I can tell are NEC gate arrays).
The sony CXD**** chips are IO expanders which are present on the boards probably for bus decoding.




(http://imageshack.us/a/img542/6159/img1033bn.jpg)

IF/log board. According to the maintenance manual (there is no service manual) the IF is 3.58mhz, or the NTSC colorburst frequency. Why? Why not?

As everything is low frequency here there's no exotic microstrip filters, just through hole varactors and 1206 smds.
Bottom left is IF input coax from RF stage.





(http://imageshack.us/a/img46/8172/img1037k.jpg)


Now all that's left is the RF section proper. The covered BNC is the optional 10mhz reference oscillator input.




(http://imageshack.us/a/img585/5949/img1039ae.jpg)


The top of the RF mainboard. I don't know jack squat about anything here so feel free to add.



(http://imageshack.us/a/img845/9620/img1040jq.jpg)


Bottom of board. RF block with type N input. If someone says it's OK to open the hood I will (and get pictures) but otherwise cant risk it.



(http://imageshack.us/a/img694/2600/img1042ed.jpg)


YIG tuned oscillator





There are about 13-14 CMOS analog switches scattered around the boards. I will be replacing those and then seeing how the self tests go after that. This seems to be a common failing point for these units.


Anyway if you have anything to add or point out feel free.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on June 11, 2013, 10:18:19 pm
Let me know what you find. I have the same model and every now and then it doesn't start properly. I still need to look into that but cycling the power works so no hurry.

This is what I found so far regarding problems with the R3131A:
http://groups.yahoo.com/group/advantestinstrument/message/139 (http://groups.yahoo.com/group/advantestinstrument/message/139)
http://www.digital-circuitry.com/MyLAB_Bench.htm (http://www.digital-circuitry.com/MyLAB_Bench.htm)
http://groups.yahoo.com/group/advantestinstrument/message/75 (http://groups.yahoo.com/group/advantestinstrument/message/75)

It seems you need to replace two DACs to fix your problem.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on June 11, 2013, 10:34:23 pm
Thanks nctnico. Seeing that yahoo message thread was what let me pull the trigger on this.
I have 15 of the CMOS spst switches on the way. I don't get any A/D errors so I think my DACs are fine. We'll see.

I think for your problem you may want to make sure the power supply is working within spec? And also check the local SMPS rails on each board.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on June 11, 2013, 10:54:08 pm
I recently purchased and repaired a couple of R3132's. That model suffers from 2nd L.O. drift with age causing PLL unlock.

I will upload some pictures of the 3132 as its RF circuits are total 'RF Porn'. Having been inside a 3131A before, I was surprised at how different the 3132 is on the inside. A totally different layout and it is all modular for ease of servicing (for Advantest, not me !)

These are very nice units when working. A good purchase. I repaired another couple of 3132's for the seller, so got a large discount on my second 3132.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on June 11, 2013, 11:16:20 pm
I just found some pictures that I took of the 3131 RF module whilst repairing it.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on June 11, 2013, 11:44:32 pm
Here are some photos of the 3132 RF module. This is very different to the 3131 and, IMHO, a better design.

These pictures are taken from 3 different 3132's and the Microprocessor PCB is from an early model. That unit had a corrupted Firmware Compact Flash card. I had to reconstruct the firmware on a new industrial CF card using the CF from a later unit....it was a PITA job as the 3132 is very fussy about its CF cards and their partitioning.

Note the earlier revision of RF module in picture '102-0550-1' and the later version in '102-0107-1'. The later module has significant improvements in the design. I like a manufacturer who continues product development after its original release to make it even better or fix 'niggles'.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on June 13, 2013, 08:28:39 pm
Thanks for the pics. The 3132 RF section is really a quite different layout.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on June 13, 2013, 09:05:18 pm
Well I replaced every DG441 cmos switch in the unit that I could find. I did not open the RF block but from aurora's photos above it was not necessary.
There were a total of 14 switches that I replaced. Behavior is identical to before, no worse, no better.

Self test fails at TOTAL GAIN, presumably because the IF STEP AMP still is not working.
I am not really sure where this physically is (the low frequency IF board, or a faulty DAC on the rf board?)

Here is a high-res picture of the RF board

http://imageshack.us/a/img600/8389/img1039cl.jpg (http://imageshack.us/a/img600/8389/img1039cl.jpg)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on June 13, 2013, 11:00:15 pm
IIRC that was the same effect the person from the links got. The problems went away after replacing the DACs.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: ve7xen on June 14, 2013, 12:49:40 am
The first poster linked apparently had a TOTAL GAIN error as well. Even after replacing the ADCs the error remained for him - until he re-tweaked the adjustment pots to the values he had saved by taking photos before cleaning them. I'd guess that if this is the only error you're getting those pots could be to blame. Perhaps clean them yourself, or they may need adjustment, there's probably an adjustment procedure in the maintenance manual?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on June 14, 2013, 01:14:28 am
From my understanding the total gain is based on the output after IF, so it would make sense it fails since the IF step amp is failing.

There is barely any info in the maintencance manual. There is no service manual. It just says "replace the boards, lol hope you have money for hands"
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on June 14, 2013, 02:12:05 am
The shielded parts of the RF pcb:

http://img16.imageshack.us/img16/6195/8kyt.jpg (http://img16.imageshack.us/img16/6195/8kyt.jpg)

There are two additional CMOS analog switches hiding in there.

10mhz reference and PLL

http://img707.imageshack.us/img707/5797/zllu.jpg (http://img707.imageshack.us/img707/5797/zllu.jpg)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on June 14, 2013, 03:24:13 am
R3261 block diagram:
(http://img35.imageshack.us/img35/7480/hix.png)

Now if this one is similar (that diagram is for a design about 5 years prior) the step amp will be around the 1-2 stage of the IF/LOG pcb.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on July 02, 2013, 05:14:17 am
Fixed.

(http://imageshack.us/a/img208/2295/uh6.jpg)

The issue was in the 4th section of the IF/LOG board. I replaced the AD606 log opamp (a $40 part) and it was not failing as bad - there was a small amount more gain in the stepamp test stage.
I then replaced the AD826 opamps after that. No change. Then I replaced the two 4072 opamps at the very tail end of the IF board. These drive the signal through the backplane connector onto the ADC / CPU board where it is digitized. Replaced both here and the problem was fixed.
The original is an ON Semi 4072 family, my replacement was MC34072DR2G.

After running warm for an hour it still passes with flying colors.

Thanks to everyone for your support
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on July 02, 2013, 10:48:53 am
Congratulations and thanks for sharing.

The nice thing about these units is that they self-calibrate so no nightmares with unavailable proprietary calibration software or routines :-)

The 313x series are nice units. You have yourself an SA that will 'see-off' the latest 'cheap' Chinese SA's, and for less money (hopefully).

I have two R3132's and they have already lead to the retirement of my R4131D's. I will keep one 4131D due to the slightly higher frequency capability (3.6GHz) and for sentimental reasons  :)  The 313x series make the elderly 4131 look quite agricultural, but I still have a fondness for their simplicity of use.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on July 02, 2013, 04:38:46 pm
Yes, I"m very glad it has a self cal function. No hope for me otherwise!

Got the floppy working too.
(http://img23.imageshack.us/img23/4541/n2a0.png)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on July 02, 2013, 04:49:20 pm
I have looked at the available options to fit a FDD emulator that takes USB sticks. Sadly I cannot find a 1.44MB PC type that is slim enough, and compatible with the needs of the 313x series. There are plenty of cheap Chinese 'Standard' height FDD emulators so I may look at modifying one of those one day. I am still equipped to work with floppies so I may just leave well alone until such time as I must move to USB on the SA.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: G0HZU on July 02, 2013, 07:35:17 pm
Advantest/Takeda do make some nice RF test gear.

I have the big 'old school' Advantest TR4172 spectrum analyser here that dates back to the 1980s. It's huge and very heavy but I really like using it and slightly prefer it to the classic HP8568B.

I'm not sure where I would ever get spares for it if a major component failed but I've been using this one since about 1990 and so far I've only had to do one minor repair on it plus I had to replace the internal NiCd battery. Advantest have labelled the battery with 'DO NOT SHORT BATTLY CIRCUIT' on the PCB silkscreen but I guess technical translations from japanese to english weren't as reliable in those days :)

It's completely different in terms of internal construction to the newer analysers with lots of separate screened boxes and everything is 'big' and heavy. For example the onboard 5MHz OCXO is the size of a coffee mug. Also there is lots of unused air spaces in the RF section with lots of semi rigid cables fitted between each internal enclosure. As analysers go, it looks quite odd and ugly on the outside but the build quality on the inside is wonderful and I place it ahead of anything from HP from a similar era in this respect. But then it cost much more than the equivalent HP8568B when it was new in around 1987.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on July 02, 2013, 07:58:57 pm
I have a TR4133 20GHz SA awaiting my attention. It is presently wrapped up and stored in the garage as its is also a bit of a monster machine. It uses a harmonic mixer design and, like your 4172, it is built like a battleship. Masses of individual modules with semi rigid coax interconnects. Such a design may keep better control of inter-stage interference and could potentially permit faster repair if Advantest just repaired to module level.

My 4133 has succumbed to the dreaded button failure and most front panel buttons are inoperative as a result :(
It will be a good project when I get around to it but it will always be a bit of a handful due to its weight.

More details here:

  http://www.tics.co.uk/testequipment/advantest/tr4133b_advantest.html (http://www.tics.co.uk/testequipment/advantest/tr4133b_advantest.html)


The 313x series are well built but they have been designed to be single hand portable so clever pressed steel chassis design has taken the place of solid castings. On the RF modules remain in castings to maintain performance.

I used to own the old TR4131 and was amazed at the decrease in weight when I got my first R4131D (the last of the 4131 series). It was a complete re-design using lighter chassis parts. Far more portable, yet still rigid. Again, the RF modules remained inside quality aluminium castings.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: G0HZU on July 02, 2013, 09:10:10 pm
I didn't realise Advantest made a 20GHz analyser.

In the case of the 1800MHz TR4172 I would guess that Advantest reverse engineered the classic HP8568A after it took the RF world by storm in the late 70s with its revolutionary design concepts.

It's as if Advantest spent several years trying to match or better every aspect of the HP8568 (at any cost) because so many things are similar right down to the 1000 x 1000 display points inside the graticule area on the CRT. One day I plan to make a display adaptor to fully exploit this capability with a modern LCD/LED monitor because the true 1MP benefit isn't really realised with the smallish CRT.

It can also do a few tricks like it can display a smith chart when a suitable RL bridge is fitted to it. However, this functionality is a bit ropey compared to a genuine VNA and therefore I've only used this feature a couple of times.

In the manual it claims it 'only' weighs 50kg but I think mine weighs more than that because it feels notably heavier than a (50kg) HP8566B and it is bigger too. Mine is loaded with various options so maybe this adds weight. Like you say, these things are built like a battleship :)

My very first analyser was an old Takeda/Advantest TR4122B with the built in tracking generator and that was a very nicely built analyser with a high quality user interface. It was pretty basic and looked very dated but  looked like it was made by Tektronix if you gave it just a casual glance and the controls were every bit as solid and refined as Tektronix :)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on July 02, 2013, 09:46:24 pm
Quote from: Aurora on July 02, 2013, 04:49:20 pm
I have looked at the available options to fit a FDD emulator that takes USB sticks. Sadly I cannot find a 1.44MB PC type that is slim enough, and compatible with the needs of the 313x series. There are plenty of cheap Chinese 'Standard' height FDD emulators so I may look at modifying one of those one day. I am still equipped to work with floppies so I may just leave well alone until such time as I must move to USB on the SA.
I have tried a slimline 3.5" USB floppy emulator in my TDS510 scope but I found it sucked quite bad. You have to press buttons to transfer files to and from the drive with no feedback. I ended up buying a box of new TDK (A-brand) 1.4MB diskettes. I bet USB floppy drives will be around for a while. Maybe buy one or two to make sure. LAN to floppy would be much more interesting (and they are available as well!).
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: G0HZU on July 02, 2013, 10:08:19 pm
Alternatively, you could use a generic USB to GPIB adaptor cable and this will work with lots of test gear. That's what I use and it's really easy to write simple apps in VB to control the instrument or get data from the instrument via GPIB. Also, this allows you to use the (freebie) HP7470 plotter emulator by KE5FX with a USB to GPIB cable if you just want to transfer screenshots to a PC. There are cheapish clones of the NI and Agilent USB/GPIB cables available these days :)

http://www.ke5fx.com/gpib/7470.htm (http://www.ke5fx.com/gpib/7470.htm)

http://www.ke5fx.com/gpib/faq.htm (http://www.ke5fx.com/gpib/faq.htm)

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on July 02, 2013, 10:39:19 pm
Oh don't get me started on GPIB  :palm:

I wanted a GPIB controller for display dumps from my R4131.....

All my GPIB boards were ISA BUS so I decided to look for USB-GPIB.

My first purchase was a very good quality USB-GPIB unit from ICS but I didn't manage to get that to work with the KE5FX toolkit.
Over the past 2 years I have 'accumulated' many GPIB controllers. I have at least five genuine NS PCMCIA - GPIB sets, a genuine NS PCI - GPIB card and several third party manufacturer USB - GPIB adapters. I got a bit carried away  :scared:  All were purchased at good prices of less than GBP50 so I am not complaining. The PCMCIA units work very well indeed and I use them with my Dell X300 laptop, as that still has such a port on it. My colleagues at work had a lot of problems using the genuine NS USB-GPIB adapter so I have tended to avoid it.

I purchased HP7475A and 7550A plotters for direct to paper screen dumps. I also found a working GPIB HP Thinkjet printer to work with the SA's  :)

I am lucky with my R3132 as Advantest saw fit to equip it with Serial RS232, Parallel (Printer) and GPIB interfaces as well as a FDD.

Thanks for the heads up on the FDD emulators. I purchased plenty of new Sony and TDK Floppy Disks and have several USB FDD drives for my computers so I will stick with the FDD for now.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: G0HZU on July 02, 2013, 10:52:45 pm
Good old GPIB...
Back in the old days I can remember trying (a lot) to get the TR4172 to plot to a HP7470 via GPIB and I had lots of help from experts. Plotting from other test gear was simple but the TR4172 wouldn't play ball. The experts told me the GPIB was faulty on the TR4172. I eventually realised that Advantest had fitted a full GPIB controller inside the instrument as an option for the 7470 so it caused a clash.

It would have been nice if Advantest had thought to put up a screen message each time we failed to try to plot using the standard method. Buried deep in the manual is a revised set of shift + function keypresses to get it to plot like a standard instrument to the 7470.

Probably for this reason, the KE5FX 7470 kit didn't work with it at first, but I eventually found a way to plot by using the Agilent IO interface to set it to an initial state before using the KE5FX software.



Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RFasic on November 27, 2013, 05:40:26 pm
Hi to Advantest R31xx SA owners,

I have some questions, perhaps more for  AURORA, as he owns and has repaired several R3132 analyzers.
I got a good bargain for one of these units (R3132) 2 weeks ago but of course with the classic Error 800: IF step amp during the calibration procedure.
Of course I read all the posts issued from a Google search about "R3131A and R3132: encountered problems" .
I tried to change 9x DG441 switches (till now ..)  as well as 3x 4072 op amps on the IF board without any success.
It's a huge lottery game without any schematics (or maintenance/service manual).
The "Execute self test" (shift 0)  gives me a PASS answer for all 5 tests.
There is probably a slight drift about the caracteristics of some components but which one to involve ??


@ AURORA:
- A) Did you encounter the same problems with all your R3132(if yes ... any suggestions)?

- B) From "full span" to "5MHz span" I get a frequency drift of 48MHz (marker reading for 0Hz) but everything return to normal for "2MHz span" and lower; I know that the YIG remains fully unlocked at high span values but do you know how to access the zero frequency trimming ajustment (software or hardware ??)

- C) Did you find an answer to the "Password" asked after executing Shift 5 ?? what does it means ? (full reset, hidden servicing menu ??)

- D) I have found a strange hardware "mod" on my IF board (BLG-024527) about u803 (DG642DY) switch getting its pins 5 and 6 in the air !! Are your boards
similar to mine ?

(http://)

I will be really pleased to read all the problems you encountered around your  R3132 's ....

Thanks for this coming knowledge, AURORA !
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on November 27, 2013, 06:36:29 pm
RFasic,

I repaired six R3132's. All had been in continuous service in a clean room environment. On five units the failures appeared in the self test (Shift 0) mode. The sixth unit would not complete its boot sequence and crashed.

Sadly I am not going to be much help to you. None of my faults mirror yours as I had problems with failed MMIC's in the 2nd LO, 2nd LO age related drift and a corrupted CF flash firmware card.

From memory the two units that I own do not exhibit the frequency error that you have described but I will need to check on that for you. I do not remember the modifications in the IF either. I will check my pictures archive.

I do not have any passwords for these units.

Sorry I cannot be more helpful.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RFasic on November 27, 2013, 09:31:05 pm
Aurora,

Thank you to try to give me the begining of a help.

I will try to obtain some more information through choosen people from R&S company.
If I can get something usefull (password, SM) for all the Advantest R31xx users, I will transmit it on this topic.

In all the cases, I will give (when it will be done!) all the procedure that I have applied to get my unit repaired (one day, for sure !).
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: rdpowers on July 18, 2014, 05:58:52 am
Hope posting to an old thread is appropriate, but I've just picked up an R3131 and am looking to repair it. I doubt I'd have the confidence if not for the few success stories, so if nothing else, thanks heaps for posting and you're all already top blokes or gals in my book.

My self-test failure is the PLL Lock Detector and if anyone has *any* information about that particular sub-system, I'd be most grateful to hear about it. The maintenance manual is interesting in that it says "Check PLL output voltage of RF unit" without mentioning what value that should be and then the proscribed fix is, predictably, just to replace the whole RF module. I'm hoping to be a little more surgical than that : )

Thanks!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on November 07, 2014, 11:51:20 pm
After several months of storage I've set up the R3131A and run the self tests after warming up. PASS!

CAL 0 fails on IF STEP AMP/TOTAL GAIN...
The only thing I haven't replaced yet are the  AD7524's. I will replace those, deoxit the pots and turn them forward/back to original configuration.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on November 08, 2014, 12:38:17 am
Did you use deoxit before? If not, then don't. Contact sprays contain acid which eats away metals so basically wrecking whatever equipment it touches. Over the years I've seen a lot of fine equipment becoming FUBAR due to contact spray.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on November 08, 2014, 12:46:10 am
IPA for safe switch and relay contact cleaning
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: robrenz on November 08, 2014, 02:21:05 am
Quote from: nctnico on November 08, 2014, 12:38:17 am
Did you use deoxit before? If not, then don't. Contact sprays contain acid which eats away metals so basically wrecking whatever equipment it touches. Over the years I've seen a lot of fine equipment becoming FUBAR due to contact spray.

DeoxIT is not just contact spray and does not corrode metals. The pdf attached was conducted by a major US auto manufacturer. Don't lump DeoxIT in with generic contact cleaners.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on November 08, 2014, 10:15:29 am
If is dissolves corrosion it contains some kind of acid. You don't want acid in equipment. If a contact or potmeter is worn out it needs replacing.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: robrenz on November 08, 2014, 02:01:41 pm
Nice idea until you are working with unobtainium parts.  ;)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: sgpee on December 10, 2014, 09:16:57 am
I have been donated a R3132 but it fails to pass self test with the error 830. Broken Freq-Corr data.

DO you guys have any idea how to fix this?

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: T3sl4co1l on December 10, 2014, 10:55:22 am
So I understand a lot of the RF structures they've got there...

And then there's this one...

(https://www.eevblog.com/forum/testgear/advantest-r3131a-spectrum-analyzer-9khz-3ghz/?action=dlattach;attach=51004;image)

What is that hunk of PCB screwed down?  Did they really make a rotatable dielectric coupler just for this?  They simply couldn't get it good enough without that adjustability?  :-DD

And actually, that's an oscillator by the looks of it; the main (345MHz was it?) VCO??

Any idea if there's metal on the facing side of that adjustable piece?

Reminds me of adjustable wavelines (usually for measuring wavelengths by nulling), or just a good old trombone... ;D

Tim
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on December 10, 2014, 11:18:58 am
Quote from: sgpee on December 10, 2014, 09:16:57 am
I have been donated a R3132 but it fails to pass self test with the error 830. Broken Freq-Corr data.

DO you guys have any idea how to fix this?
Lucky you! I'd like an R3132 as well even if it needs some TLC. In the R3131 some ADC/DAC and analogue switches can break. Perhaps yours suffers from the same problem. Or it may be you just need to connect the calibrator output to the input and do a self calibration.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on December 10, 2014, 09:20:10 pm
The 3132 PCB image is of the (IIRC) approx 6GHz 2nd Mixer VCO. It uses a variable dielectric 'pad' to centre the VCO mid range point. The Varicap diodes pull it + and - from the set point. The centre point setting drifts over the years possibly due to component aging or dielectric characteristics changes. eventually the drift exceeds the compensation range available to the VCO controller and the unit fails self test. I cannot say I like the agricultural looking design of the VCO, but it does seem to work OK. The movable dielectric 'pad' does not have any metal content and is plain dielectric material.

I do not think the VCO is the cause of the error in the latest 3132 question. The firmware sits in the 16MB Sandisk Compact Flash card, Calibration data is stored in EEPROM on the modules. I have not investigated such so cannot provide further comment.  The design enables replacement of individual RF, IF and Synth modules without needing to re-calibrate the analyzer. Each new module comes pre-calibrated and ready to mate with the original modules in the unit. Modules are swappable between different 3132's without affecting calibration. On boot, the analyzer self calibrates the RF, and IF chain using stored calibration data and BITE tests. Its a pretty clever little unit really. One unit I had for repair would not boot and that was corruption of a file in the CF card. Corruption of calibration data on a module seems likely in this latest case. I have no easy fix for corrupted calibration data. Sorry. The Lithium battery on the motherboard is not system critical and only preserved stored image data and the RTC

Aurora
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: sgpee on December 14, 2014, 01:05:32 pm
Quote from: sgpee on December 10, 2014, 09:16:57 am
I have been donated a R3132 but it fails to pass self test with the error 830. Broken Freq-Corr data.

DO you guys have any idea how to fix this?


I was able to clear this error. All I had to do is to disconnect the LCD from the system and let it be without power a few hours. When I put back the system together, all was good. I was able to pass every test. However, when I try to measure I cannot get it to work.

I try to use CAL output to input and try to see the signal and I cannot observe anything. I try to see my wifi etc and same story. Either the RF front end is toast or something else is going on. What should I do next?

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on December 14, 2014, 01:18:56 pm
A spectrum analyser is just a sophisticated superhet receiver with all the usual components in the RF chain.... Mixers, Local oscillators, amplifiers, filters and detectors. Fault diagnosis follows the same routine as a receiver. Start with checking all power supply rails and then follow with the 'half split' methodology to determine which stage is not operating correctly. Then determine if the stage is faulty or is lacking a required input.

The user manual for the 3132 contains some useful information on how the unit works and parts of the circuits. Use the block diagram as a guide to using the 'half split' method.

Sadly working on spectrum analysers often requires some quite expensive test equipment and even another spectrum analyser for signal analysis.

This is one of the reasons why broken ones sell relatively cheaply.

Edit. If unsure about half split methodology, Google has plenty on the technique. Example here:

https://books.google.co.uk/books?id=sGbwj4J76tEC&pg=PA362&lpg=PA362&dq=half+split+method+on+superheterodyne&source=bl&ots=U0dr7fI1lG&sig=efhuZIRgg2fwOeuI9oBTMOcfHKE&hl=en&sa=X&ei=646NVPrsBYn4UomxgKAB&redir_esc=y#v=onepage&q=half%20split%20method%20on%20superheterodyne&f=false (https://books.google.co.uk/books?id=sGbwj4J76tEC&pg=PA362&lpg=PA362&dq=half+split+method+on+superheterodyne&source=bl&ots=U0dr7fI1lG&sig=efhuZIRgg2fwOeuI9oBTMOcfHKE&hl=en&sa=X&ei=646NVPrsBYn4UomxgKAB&redir_esc=y#v=onepage&q=half%20split%20method%20on%20superheterodyne&f=false)

http://www.radioremembered.org/superhet.htm (http://www.radioremembered.org/superhet.htm)

http://www.wb6nvh.com/GE/Trouble.pdf (http://www.wb6nvh.com/GE/Trouble.pdf)

http://www.radio-electronics.com/info/rf-technology-design/superheterodyne-radio-receiver/double-superheterodyne-receiver.php (http://www.radio-electronics.com/info/rf-technology-design/superheterodyne-radio-receiver/double-superheterodyne-receiver.php)

Aurora
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on December 14, 2014, 11:11:56 pm
What can work is to follow the signal path. From the input mixer you should have a signal which is within range of a decent oscilloscope. From there you can see if all the mixer and detector stages work. You'd probably have to figure out which is what from a block diagram.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on December 14, 2014, 11:42:31 pm
OK, to help things along a bit I attach the block diagram that I created when looking at an R3132. I forgot that the user manual did not contain such, I had to do the work myself to get a feel for how teh R3132 was configured and the various L.O and I.F. frequencies.

I can't find the original file for the moment (its somewhere on one of my laptops) I hope the picture is readable.

For info, the important details are:
1st L.O. (YIG Oscillator) range is 4261MHz to 7261MHz
1st I.F. is 4261MHz
2nd L.O. is 3840MHz (this has the dielectric trimmer and is phase locked to 3840MHz)
2nd I.F. is 421Mhz

Note the monitoring ports from couplers in the 1st and 2nd L.O signal paths. Useful for quick checks. The 2nd L.O. monitoring port is a pig to get at as it is on the side of the RF module. I used a fine wire in the SMA socket to create an aerial that I could monitor with another spectrum analyser and EMC probe. It worked a treat as the level on the port is pretty high. The 1st L.O monitoring port is on the rear of the RF module. There are two ports, one for an optional TG and the other for monitoring. Either will do for monitoring the frequency of the YIG Oscillator but you need equipment capable of working at those GHz frequencies. I used an 8GHz SA that I borrowed from work.

Also check that the CAL output is the correct frequency.

Enjoy  :)

Aurora
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: wokkel on April 19, 2015, 08:26:49 pm
Hello,

I bought a R3131 which failed the Self test due to an empty CPU battery.
I replaced the battery and now it works :D
The spectrum analyzer has option 40, a second 43 DBM Rf input.
The problem is that the spectrum analyzer tells me "Option required" when i want to enable the second input.
Is there any way to re-enable this option in the software of the spectrum analyzer?

Thanks
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: iz5rgo on May 30, 2015, 10:04:40 am
Hi, I have to buy a R3131A impeccably maintained for the sum of 800 € but this has a problem with the tracking generator, was replaced the battery, no longer recognizes the generator, as if it were installed. How could I fix this?
Regards Alessio iz5rgo
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: diarcy on June 30, 2015, 05:02:23 pm
Hello all,

After replacing the Lithium Battery on my R3131 (which lasted 18 years), the RTC is again working, but my Tracking Generator (Option 74) is no longer recognized. This seems to be a common problem when the battery is replaced but I have yet to see a solution.

Does anyone know how to re-enable the Tracking Generator after the battery has been replaced?

The spectrum analyzer works great otherwise! No other problems!

Thanks!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on June 30, 2015, 05:25:19 pm
Sadly the volatile RAM, that is maintained by the lithium battery, contains the  option keys.

I know of no way to replace or bypass these as they are unique and locked to the serial number of the SA. To my knowledge, the R3131 has never been subjected to analysis for the purposes of 'hacking' it

Your only chance at the moment is a request to Advantest for help. They may, or may not, be interested in providing such help.

Aurora
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: wokkel on June 30, 2015, 06:06:08 pm
If you push Shift and 5 the spectrum analyzer  asks for a password.
Maybe this gives access to some kind of service mode?

( i have the same problem with  the second input which is not working after battery replacement)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on June 30, 2015, 06:12:14 pm
How many options are there for this spectrum analyser? I also own an R3131
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on July 01, 2015, 12:06:12 am
Dump the flash and load in IDA?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: diarcy on July 01, 2015, 02:38:13 pm
Thanks for the insight, Aurora.

This seems like a very poor way to design a product if they did put the option codes in RAM. Surely EEPROMs were available in the 1997-1998 timeframe. I wonder why they would do something like this... I mean, the designer should have known the battery would eventually die at some point.

I've contacted Advantest's service company to see what are my options. The last time the instrument went in for a repair (which also includes calibration) was, I believe, somewhere around $1500, flat fee.

Since my R3131 is functioning just fine, I would hate to pay anything for restoring my instrument to the way it was before the battery died...

I'll keep you all posted on what I find.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on July 08, 2015, 07:14:46 am
I just posted a question asking how you get the r3131a apart. I took the back cover off and got stumped from there. I guess I should carefully change the battery under power as I have a tracking generator on mine.

Question is how do you get it open?  I wanted to tweak the master oscillator unless it can be done in software?  When measuring a 10Mhz signal the counter reads low by 182hz.  Just enough to annoy me.

Thanks
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: diarcy on July 13, 2015, 02:56:27 pm
There's an way to adjust the master oscillator without taking the back cover off. There's a small hole on the back panel next to the external 10MHz input. Insert a small screwdriver to adjust the pot which controls the frequency. Hope this helps!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on July 14, 2015, 09:50:22 pm
Wow,  thanks,  I remember seeing something next to the 10M input.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: flolic on July 15, 2015, 07:44:12 am
What kind of battery is in the unit, lithium? What replacement should I get?

I don't want to loose +43dBm input option on my unit.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: diarcy on July 15, 2015, 09:18:52 pm
On my R3131A, the battery is a 1/2AA, 3.6V Lithium, Type ER3 from Maxwell. The date code on mine was 98-06 so it lasted 17 years! (Though, it was completely dead... 0.3 Volts.)

I could not find any ER3 types but I ended up using a Tadiran TL5902/PBP which is also a 1/2AA. Mouser has this battery for $5.95.

I'm not sure how one would replace the battery without loosing power to the RAM -- if that's where the option codes are stored. I'm sure there's a way to do this. Maybe if you can trace out the battery circuitry you can find a way to do this.

The battery is located on the CPU board which is the top-most board. It's easy to take the back cover off and then (gently) pull the board out. The floppy drive will come out as well.

I still have not found a way to re-enable the Tracking Generator... and I have not yet heard back from Advantest's Service Partner.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: diarcy on July 15, 2015, 09:27:52 pm
cncjerry -- do you have a copy of the Maintenance Manual? This has the setup procedure for making the adjustment in Section 4.

The adjustment is to be made at 1GHz using the Frequency Counter on 1Hz resolution. In order to make the adjustment, one would need a 10MHz Frequency Standard which is fed into a RF Signal Generator that can output 1GHz at -10dBm.

On mine, after a good 30 minute warm-up, I was able to adjust the Master Oscillator to within 5 ppb or so. (That is 5Hz out of 1GHz.)

In general, the Maintenance Manual is not very good. There are no schematics.

I found a scanned PDF copy on the Internet.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: diarcy on July 15, 2015, 09:33:20 pm
If you need the R3131 Maintenance Manual, I Google'd the following:
Advantest R3131 maintenance manual

The first link that popped up was "Manuals - KO4BB.com"

I have no idea who's site this is but the very first item is the R3131 Maintenance Manual. It's a PDF so it should be safe from any viruses.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on July 16, 2015, 06:22:20 am
I have a 10M standard but no 1Ghz generator.  I'll have to figure out a way to do this correctly. Usually that's means buying something.  I've used the TG from my 3131a pretty effectively.  I have to tune some 1Ghz cavity filters I am making so maybe it is time for a new signal generator.

I am milling copper cavity filters for the Scotty spectrum analyzer.  I thought I would build one as I like the idea of having a pretty complete instrument where I know all the software.

I've downloaded manuals from K0bb, very good site.

The battery has me buggged, I would hate to lose my TG in the advantest. Couldn't you solder a battery onto the existing traces then clip the old one out?

So how do I get the darn thing apart anyway?  I'm not going to rush into it, but I could never figure it out, though I didn't spend much time with it.  I took the back off, the front bezel, but stopped there when I saw all the sheet metal.

Thanks for the oscillator tips. 



Quote from: diarcy on July 15, 2015, 09:27:52 pm
cncjerry -- do you have a copy of the Maintenance Manual? This has the setup procedure for making the adjustment in Section 4.

The adjustment is to be made at 1GHz using the Frequency Counter on 1Hz resolution. In order to make the adjustment, one would need a 10MHz Frequency Standard which is fed into a RF Signal Generator that can output 1GHz at -10dBm.

On mine, after a good 30 minute warm-up, I was able to adjust the Master Oscillator to within 5 ppb or so. (That is 5Hz out of 1GHz.)

In general, the Maintenance Manual is not very good. There are no schematics.

I found a scanned PDF copy on the Internet.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: corax on July 16, 2015, 07:18:35 am
Quote from: cncjerry on July 16, 2015, 06:22:20 am
The battery has me buggged, I would hate to lose my TG in the advantest. Couldn't you solder a battery onto the existing traces then clip the old one out?

Apparently the 3132/3162 did things differently with regard to the TG.  I hadn't read about any of these problems and went ahead and replaced the same battery in my 3162 (old battery was completely dead).  TG still worked afterwards (aside from a loss of PLL lock as it warms up; trying to fix that now).

I bet you could solder the new battery in before cutting the old one out.  Or maybe use a temporary external current limited power source during the swap.

I wish that schematics/parts lists were available for these things.  I've figured out a bunch of the circuitry in the r3162's TG, but there are some mystery parts in there.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on July 16, 2015, 11:17:45 am
Standard operating procedure for replacing a Lithium cell whilst maintaining power to the SRAM...

1. Buy a 2 cell AA or AAA battery holder with flying lead output for connection to a PCB.
2. Fit 2 cells in the holder  ;D
3. Solder the flying leads to the supply rails that the Lithium battery maintains (observing polarity)
4. Cut the lithium battery off of the PCB
5. Desolder the lithium battery pins
6. Insert the new Lithium battery and solder its pins.
7. Desolder the battery holder flying leads.
8. Job done  :)

Note this is all done with the power to the equipment OFF !

For the very nervous amongst you, you can usually insert a 1K resistor in series with the battery holder flying leads, though this is not normally needed in the real world.

This approach came from an OEM service manual and is not some 'hack' method  :-+

Aurora
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on July 27, 2015, 06:44:46 pm
In the procedure above, why are two batteries used, to keep the dead battery from drawing it down?  Is the 1k preferred?   

Has anyone sent a 3131a to Advantest repair to have the battery replaced? If it was less than $300 I would pay it.  I can't lose my tracking generator...
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on July 27, 2015, 09:52:56 pm
2*1.56V = 3.12V
The minimum voltage threshold of some volatile memory is approx 2.5V.

1K resistor is not essential. Battery pack is connected to the volatile memory and the dead Lithium cell is isolated by the series diode between it and the memory supply rail.

Aurora
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on October 19, 2015, 01:05:17 pm
Quote from: diarcy on June 30, 2015, 05:02:23 pm
Hello all,

After replacing the Lithium Battery on my R3131 (which lasted 18 years), the RTC is again working, but my Tracking Generator (Option 74) is no longer recognized. This seems to be a common problem when the battery is replaced but I have yet to see a solution.
Maybe there is. In my R3131 the battery went flat and after replacement it wouldn't start properly. However.. I found a switch on the CPU board and when I pressed that while my R3131 was powered on it came back to life. This button probably initiates some kind of RTC data init. I may revive the tracking generator as well.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: krivx on October 19, 2015, 01:42:00 pm
Quote from: Fraser on July 16, 2015, 11:17:45 am
Standard operating procedure for replacing a Lithium cell whilst maintaining power to the SRAM...

1. Buy a 2 cell AA or AAA battery holder with flying lead output for connection to a PCB.
2. Fit 2 cells in the holder  ;D
3. Solder the flying leads to the supply rails that the Lithium battery maintains (observing polarity)
4. Cut the lithium battery off of the PCB
5. Desolder the lithium battery pins
6. Insert the new Lithium battery and solder its pins.
7. Desolder the battery holder flying leads.
8. Job done  :)

Note this is all done with the power to the equipment OFF !

For the very nervous amongst you, you can usually insert a 1K resistor in series with the battery holder flying leads, though this is not normally needed in the real world.

This approach came from an OEM service manual and is not some 'hack' method  :-+

Aurora

Doesn't this require a floating soldering iron? I don't think touching an ESD-safe tip to a powered rail is a great idea...
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on October 19, 2015, 01:56:09 pm
Not an issue. The SA unit is not connected to the mains. The only power present is that from the batteries and the ESD status of the soldering Iron has no effect on such.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Marcel on October 20, 2015, 02:25:15 pm
https://www.youtube.com/watch?v=ZQ_S4Br1ftg (https://www.youtube.com/watch?v=ZQ_S4Br1ftg)
https://www.youtube.com/watch?v=nZ2W3clPFdA (https://www.youtube.com/watch?v=nZ2W3clPFdA)

Regards,

Marcel
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: marshallh on October 20, 2015, 05:14:54 pm
Thanks Marcel, I inferred from your video that Total Gain cal failure was due to overall amplification drop occuring while heating, falling outside the range auto-cal could compensate for.
Your solution was to increase the gain of one MAX4106 opamp. Is this right?

I couldn't find the circuit in my pictures so I will check under the RF cans on the RF board.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Marcel on October 21, 2015, 03:07:15 pm
Marshallh

Your solution was to increase the gain of one MAX4106 opamp. Yes that is right.

This is not my video but You-Tube is my (best) friend.

Regards,

Marcel
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on January 31, 2016, 07:14:25 pm
Hello,

I came across this post while searching for answers with my R3132 and I am hoping someone might be able to help me out.

Long story short I have a R3132 that I am trying to sell on eBay. It seemed to be 100% operational but I figured I would send it in for Calibration first as it would add a level confidence for the buyer and hopefully get me more money.

The unit ended up failing calibration and now I am trying to look into some common issues with the unit (that is how I ended up here).

After i saw some posts about the Self Test I decided to run it and I am getting 2 failures, CPU and RF.

I noticed that the date does not hold so I am assuming that the battery is dead and I wonder if that is causing the CPU failure. But I am not sure about the RF failure.

I don't know if it is helpful or not but i have attached a copy of the failed Calibration Certificate.

Thanks in advance.

 
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on January 31, 2016, 07:19:48 pm
After I replaced the battery I had to run the self cal again to make accurate measurements so it is very likely the bad battery is causing your problems.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on January 31, 2016, 07:21:50 pm
Nctnico,

Thanks for the response, I will look through the manual to try to find the replacement battery #.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 02, 2016, 11:03:15 pm
**Update**

Sorry to hijack the thread again but there doesn't seem to be any for the 3132...

I went ahead and replaced the battery, now I get no errors on the initialization and the CPU Error, when I run the "Self Test" has gone away.

However I still have the RF Fail with the "Self Test" and when I try to run the "Self Cal" I get a 807 Error no calibration signal.

Any ideas?

Thanks
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on February 02, 2016, 11:42:54 pm
Try and press the button on the CPU board while it is on like I described in a few posts earlier. I doubt it will work but if it does it is a simple fix. If not then you are looking at a repair.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 03, 2016, 12:41:59 am
I don't think that switch is something I can get at while the unit is powered on.

Plus, after reading this thread over and over, as well as one on a Yahoo group I think it might have something to do with that strange sliding switch in some of the pictures. However, I'm not sure how to go about adjusting it.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on February 03, 2016, 09:17:31 am
Quote from: jc81382 on February 03, 2016, 12:41:59 am
I don't think that switch is something I can get at while the unit is powered on.
The push button is near the rear so just leave the rear cover off and use a plastic pen or a thin finger.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 03, 2016, 11:16:31 pm
nctnico,

Thanks for the idea. I just tried it and all it did was reset the unit, but worth a try.

I decided to take out, what I assume to be the RF Board, to inspect this "dielectric switch" that I keep seeing in the pictures.

Now I am not a RF or Electronics technician, I graduated from a tech school for Electronics, I work at a Calibration Lab and I like to tinker, so a lot of this is over my head. But if anyone can explain to my why the position of these switch's seems to be different on every unit and how adjusting them may or may not help my situation that would be greatly appreciated.

Attached is a pic of the position I found my unit it.

Thanks
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: T3sl4co1l on February 04, 2016, 12:14:28 am
A structure like that would be for fine tuning a filter's frequency, bandpass, matching, etc.  It might compensate for tolerances in the PCB fabrication, or variations in device impedance.

I think you'd want to run a full E&M sim on it, just to be sure.  The range of effects it can have is quite broad (its position varies by electrical angle along the transmission line structures, as well as contributing loading impedance with those isolated chits, which are at some distance as well, so will affect the response in a complicated way again).

Tim
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on February 04, 2016, 12:32:14 am
The calibration signal being absent can have any number of reasons. The only way to find out is by determining where the calibration signal is generated and follow it from there. The structure on the picture is not a switch but some kind of adjustment so don't touch that.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 04, 2016, 12:41:36 am
Thanks guys,

I noticed that the "cal out" has a 30 mHz -20db printed on the housing. I assume that is the standard output.

Maybe I will take the unit to work and try to supply 30 mHz -20 db into the RF in and run the "auto cal" program. I assume that as long as the input sees that input, it should adjust/offset. I know the RF in works because although it failed calibration when we attempted it at work it was getting readings. So maybe it is just the cal out that is bad.

I can also see if I get a reading on another Spec A from the cal out when I initiate the auto cal.

I think that will be the extent of my abilities.

Thanks again, if anyone has any other suggestions it is greatly appreciated.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on February 04, 2016, 12:44:59 am
Wait a minute... you have a model with a cal out connector! That should be connected to the input when doing a self calibration!
In the R3131A that connection is made internally but in your spectrum analyser you'll have to make an external connection.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 04, 2016, 01:22:28 am
yeah, I know... Unless i have a bad cable, its as if the cal out is not putting out a signal or the RF in is not sensing it.

I assume the RF in works because we were able to get it to read a signal when fead form an external source when we attempted calibration (not the internal calibration but they type provided by a Calibration Lab), it was just OOT.

So that leaves me to assume the issue is with the cal out.

When i run the self cal I am still getting a RF Fail. So does the system know that there is an issue with the RF board? I have no idea.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 04, 2016, 11:41:32 am
Some comment on this........

First check that the calibration signal is present at the output port. It should be the frequency and amplitude stated in the spec. The calibration signal is unlikely to fail on these units. It should still be rested though.

The PCB Dielectric trimmer is part of the 2nd local oscillator VCO tuned circuit, and sets the correct centre frequency around which the Local Oscillator may be tuned by the phase locked loop. There are a pair of varicap diodes under control of the LO PLL that adjust the frequency as required whilst the SA is operating.

When the SA starts its self calibration and test routine it checks that it can see the Calibration signal and that the levels are correct. If The LO has drifted too far off its centre frequency, the PLL cannot bring it into lock and so the Calibration signal is not seen on the correct frequency or correct level.

The SA will often still work but as its LO is not working correctly, accuracy will be off.

Correction of this situation involves adjustment of the dielectric trimmer to bring the LO centre frequency back to spec and enabling the PLL to drive it over the correct operating range. Adjustment is done as detailed in my guide which I believe I posted in this thread ?

The adjustment of the dielectric trimmer is very sensitive and it is important to set the centre frequency accurately using an accurate SA or frequency counter connected to the LO monitoring port. It is not recommended that the dielectric trimmer be adjusted without monitoring the frequency as it does not operate in a predictable manner when moved.

I just took a quick look at this thread and did not see my 2nd LO dielectric trimmer adjustment guide. If it's not on the forum I will upload it.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 04, 2016, 11:55:07 am
Just remembered, I uploaded my 2nd LO adjustment guide to the Advantestinstrument Yahoo Group. You can download it from there. Its over 1MB so cannot be attached here.

https://groups.yahoo.com/neo/groups/advantestinstrument/files/-%3DAdvantest%20-%20R3132%3D-/

UPDATE & WARNING

Please read all of this thread. It has become apparent that two versions of R3132 RF module were made. My newer modules use a dropper resistor in series with the 2nd LO MMIC and buffer MMIC supply rails. Earlier versions of the RF Module do not contain this dropper resistor ad use a lower supply voltage to the MMIC's. This thread contains details of teh lower voltage level measured by a fellow forum member.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 04, 2016, 12:21:26 pm
Fraser,

Thank you so much for the info and for the link. I wasn't able to see it on the Yahoo group, at first, because I wasn't a member of the group originally.

I will ask around at work to see if I can get my hands on some of the necessary tools/equipment to attempt the procedure called out in your adjustment guide. Can you confirm what I should have? I assume another Spec A and a Power Supply?

I am usually willing to try anything, especially since its not really working now I almost have nothing to lose.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 04, 2016, 12:48:15 pm
You will need a power supply, multimeter and some means to measure the 3805 MHz that comes out of the Local Oscillator monitoring port (SMA socket located on the side of the module).

The power supply should be of good quality and provide an accurate 11.3V for the module. The multimeter can be any digital unit capable of reading the approx 10.3V Varicap diode bias voltage.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: l0wside on February 04, 2016, 12:52:33 pm
An R3131 is on the way to me, and before I destroy it the very first day, I´d rather ask the experts here before.

The R3131 user´s manual says about the input:
"N-type input connector 50Ohms. Analyzer input connector: Frequency range is 9 kHz to 3 GHz; the maximum input level is +20 dBm or ±50 VDC max"

The last part (in bold) confuses me. At a SA training at Agilent, the trainer had the complete group repeat the phrase "never ever apply DC to an SA input". The R3131 manual suggests otherwise.
What should I believe?

Max
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 04, 2016, 12:57:54 pm
Fraser,

Excellent, thank you again.

I have our Electronic Team Leader/Main RF Tech reviewing your procedure make sure I don't miss anything and to give me any pointers.

I will keep you guys posted.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 04, 2016, 01:21:49 pm
@IOwside

As a spectrum analyser is a test equipment for AC signals you would not normally inject DC into its input.....BUT an AC signal can be sat on a DC bias voltage.

The Advantest SA contains a DC blocking capacitor rated at 50V DC. Hence the specification on the front panel. I also use a higher rated DC blocking adapter when I know DC bias is a possibility. It's just good practice, but the SA will cope with a DC bias up to 50V without damage.

Static discharge is also the enemy of Spectrum Analyzers. Be vet careful if considering connection an SA to a non DC shorted antenna such as a discone. Static discharge can damage your SA's first mixer when running with no input attenuation applied.

Another way to fry your SA input is by injecting a spectrum of signals whose total energy level overloads the SA's input specification. This is especially important if working with spread spectrum or noise generators. The total energy present is not just that of one signal 'spike' , it is the total energy of all signals within the pass-band.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: l0wside on February 04, 2016, 01:41:11 pm
Fraser,

thank you so much. I am aware that measuring DC with an SA does not make any sense, but my application (EMC precompliance on devices with a 30V DC supply) seems to match the R3131´s possibilities quite well (and fits your description "AC sat on a DC bias voltage").

I have ordered a DC blocker anyway (set me back under 7 EUR, direct from China) and will put it in the drawer, just in case.

Max
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 05, 2016, 03:03:15 pm
Fraser,

I was just reviewing your procedure with our QA Manager who uses to repair SA's, hoping to get additional help and he noticed something, that i saw before but didn't may much attention to.

If you look closely at the picture in your procedure and a picture I took when I opened my unit up there seems to be an additional trace or component that was added to the circuit. I have attached pictures and circled where this is located.

I also noticed originally that when i went to open the case the first time there were 2 sets of marks on the housing screws (one black and 1 red... all of the other marks are red so I assume that there was a repair done on the unit and they used black marker to mark to position of the screws).

Do you have any idea what this additional trace might be for? Should I consider removing it before temptation your procedure?

Please let me know your thoughts.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 05, 2016, 04:20:43 pm
You appear to have an earlier version of the module. Fortunately I have also repaired that exact same version as I worked on five of these SA's, all with the same problem. The components added across the varicap diodes are a modification carried out due to issues with tuning the 2nd local oscillator.

My procedure is still applicable and you should not make any changes to the unit.

Best Wishes

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 12:22:32 am
Fraiser,

As always thank you for the input...

So I was unable to get my hands on another Spec A so I opted for a Frequency Counter, knowing that it would not let me make all of the measurements I needed but I was hopeful I would be able to dial in on the 3.805 Ghz Frequency.

I started off by checking the frequency coming off the Cal Out and it was 29.997...

Then I took everything apart and took my first measurement on the SMA Port and got 3.742...

I the adjusted the pad and got it as close as I could to 3.805 and ended up with 3.797...

I figured since this was as good as I could get i would put it back together and give it a try and it still failed RF Self Test and Auto Cal (as you can see by the red warning in the pic).

At this point my cal out is giving me almost exactly 30 MHz though.

Anything I am missing?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 06, 2016, 12:25:10 pm
Yes there are two more checks to carry out

1. I monitored the 2nd LO frequency when it was back in the SA to ensure that the PLL brought it onto the correct operating frequency. This is not an easy test however as access to the side mounted monitoring port is obscured by the chassis rails. I solved this by placing as this copper wire into the SMA socket centre pin to act as an aerial. Make sure it approx 0.5 inches long and apart from the connection with the centre pin, insulated from the chassis.
I them used an EMC probe to sniff the 2nd LO signal frequency.

2. I used a meter to measure the 2nd LO PLL control voltage at the detailed feed through point. It should be very close to 0V.

In your case your frequency counter will not be sensitive enough to pick up the signal from my suggested tiny leakage antenna in the monitoring port. If you can use a longer wire and direct connection to the counter input you may get enough signal to count. The monitoring port is fed from a directional coupler pick-off so a longer wire should not cause you any problems and this is not accurate level measurement test anyway.

Test 2 just requires you to place a long test wire on the test point and feed it to the rear of the chassis to Connect to your meter.

Did you measure the voltage on the Varicap diode drive point when you powered the module ? It should have been around 10.33V wrt chassis. Anything else would be evidence of an issue and would make alignment using my simple method void.

If the 2nd L.O is working fine and all checks prove it is on frequency and the PLL is happy, you have another problem in the signal path that we will need to diagnose. 1st Mixer damage is one possibility but hopefully not the case.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 02:26:52 pm
I did not get to check the voltage when it was back in the SA yet, but the voltage at the varicap ranged from 10.3 to 10.4. I checked it multiple times while adjusting the freq.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 06, 2016, 02:50:51 pm
Varicap voltage looks good. Just check if it is close to 0V on the PLL control line when in the chassis and working. If so, you should have PLL lock.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 03:30:55 pm
Fraser,

Do any of the pictures say where to connect tot make the " Connect a DC voltage meter between the PLL control voltage monitor wire and chassis"?

I have the cover back on and am about to put it back in the SA.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 03:33:33 pm
Fraser,

Never mind, I see that you saw a few steps before.

It looks like the other side of the blue wire that was feeding the power is the adjustment stage. Sorry
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 03:54:09 pm
Fraiser,

I don't think i'm taking the reading the right place.

The only passthrough that I could see with a blue wired was on the opposite end of the of the board, sandwiched between the top and bottom boards in the "gap area" (for lack of better works. Plus it was on the opposite end of the board  from the Cal Out BNC. When i tried to take a measurement here I got 0V, like absolute 0V like there was no voltage there so I assume I was in the wrong place.

Do you see in my pictures where I should be getting the measurement from? I assume I should be grounding to the chassis?

Thanks
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 04:00:03 pm
Sorry forgot to attache the pics
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 06, 2016, 04:54:31 pm
Hi

Take a look at the last picture in my alignment guide. The feedthru is right behind the Calibration socket and has a blue wire coming off of it. Exactly 0V wrt chassis would be unusual but not impossible.

The final confirmation would be to measure the frequency on the 2nd LO monitoring port whilst the module is back in the chassis.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 05:40:59 pm
So the plot thickens...

It seems that was confused because my unit does not have that pass thought.

I took off the top circuit board to get a good look/pic of the unit and as you can see the only pass thought on the entire this was the one i was trying to use in the first place. (top right area)

I also added a pic of how I connected and how I was trying to take the measurement.

Do you think i should be expecting a voltage at this point?

Was there anything else I had to do other than turning the unit on to get a reading?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 06, 2016, 05:56:43 pm
Hmmmm how odd. I have not seen a unit without that feedthru before. I will need to check my notes on this SA to see where I was monitoring the PLL voltage. Sorry I do not recall the purpose of the feedthru that you are monitoring.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 05:59:40 pm
sounds good.

There was another plate that was under the circuit board and I took that off to see if the pass throughs came up from there and they did not. it was just another circuit board that has some RF Cable going thought the sidewall  that connected to the circuit board that usually rests on the top.
 
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 06:03:19 pm
Another question.

How sensitive are the cables that connect the RF board to the board above it?

I noticed when I was connecting things back up that one of the cable was pretty crimped (it was the one that crosses over the copper SMT.

I was just wondering since that connects the 2 boards together could that be causing the RF Fail?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 06, 2016, 06:38:12 pm
Ok I just checked the paper files that I had knocking around for the 3132. My memory has failed me. I have met your exact model of module before. I have a couple of printed pictures showing the difference ! Attached.

The aim of the measurement exercise is to get onto the control voltage line of the 2nd L.O. varicap diodes whilst the covers are on and the module in the chassis. The feedthru that I specified is a DC connection from the varicap diodes to the PLL control voltage driver. I could have chosen a point on the PLL board but that is just making life difficult for no good reason  :)

In the case of the module that did not have the convenient monitoring point where I expected it, I would have carried out DC continuity tests between the varicap diodes common point (between the two diodes) and the feedthru's that emanated from the modules metal shell. One of them would be the control line from the PLL and provide continuity. The blue wired feedthru could well be the right one but you need to prove it.

I have bee thinking about your previous reading of 0V. If you are monitoring the PLL control voltage, it could be that you have a fault shorting the control line to 0V. The fault could be the driver chip on the PLL board or a short to chassis somewhere along the control line. Such a short would still bring the VCO almosyt onto its correct frequency as the nominal control voltage is  approx 0V, but the PLL would have lost control of that VCO which can only be bad !

With regard to your crimped solid coax cabled. The copper coax cables are vulnerable to damage and if distorted too badly they can either present a poor impedance match, and standing wave issues, or even a short of the centre conductor to the outer copper screen. The insulation is PTFE which is quite soft and easily crushed to the point of a short, inner conductor to outer. To do so the coax would need to be pretty seriously bent to a right angle though. Minor outer copper sleeve distortion can be tolerated. Much depends upon the signal being carried by the cable and its frequency.

Keep us advised on progress and I will try to help but my repairs were an awful long time ago and the old memory is failing a bit. I am not in a position to dismantle either of my R3132's at the moment so regret direct comparisons are not possible.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 07:42:58 pm
Ok... so here is what i got...

I took the board out again and took the cover off.

I put my DMM at the 2K ohm (continuity check setting) to that passthrough that was giving me 0V and checked the common point of the vericaps and got nothing (OL on the DMM).

I found the other side of that passthrough and immediately got 0 Ohms and beep (as expected).

But then as i touched the chassis and other passthroughts (like the one that I was applying voltage to when adjusting the Freq) and i kept getting reading of .3XX.

Do you think this means a short?

I wouldn't expect that point to be giving me a reading when touching the chassis and the there "blue" passhtroughs.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 06, 2016, 08:01:28 pm
This test was only to find low ohmage continuity in order to trace the control line. You cannot deduce much from your other readings as the control line is coming from a driver IC and we do not know what effect such has. However 0.3k ohms is not low enough to be a shorted control line.

You need to check the 2nd LO frequency whilst the SA is operational. No way of avoiding it. I know it's a pain with regard to access, but is is necessary.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 08:09:54 pm
So basically find a way to hook up the counter to that test port on the side that was monitoring the Freq before?

Since I don't have any options that take up space on the right hand side should I just try to drill or remove a spot on the chassis where that port is so I can plug into it?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 06, 2016, 08:25:04 pm
EEEEEK drill the chassis....... Nooooooo. That is a recipe for a swarf disaster

Take a piece of solid core insulated copper wire with a core approx 1mm diameter. Strip off approx 5mm of insulation and bend the bare wire through 90 degrees. Insert the bare wire into the SMA connector. Run the wire along the side of the module about 50mm and hold it in place with tape. The end of this wire should be positioned such that it can be accessed by your frequency counter probe. Use the module case for the ground. Keep the wire as short as practical. This is bad RF practice on many levels but as the port is connected to a directional coupler monitor port and we are just checking frequency, it is acceptable.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 06, 2016, 08:52:19 pm
Hahaha....

I will give it a shot later today (just got to a birthday party) and let you know what happens.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 07, 2016, 01:06:01 am
Fraiser,

Here is what I have.

I took a piece of CAT5 cable and removed 2 of the conductors.

I put one into the center of the port like you said and took the other and mounted it to one of the screws next to the port.

I then taped the wires down to the side of the unit and slid it back in place, then attached all the connections.

When I tried to get a reading off the Freq Counter it was all over the place. The pics attached were all taken within 15 seconds of each other.

I will wait till you have a chance to review and let me know your thoughts.

Thanks

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 07, 2016, 01:59:24 am
I see where your problem lies.

The unscreened CAT5 wire from the port is way too long. It needs to be kept as short as possible. You need a proper coaxial test lead to go from the frequency counter to the short CAT 5 cable. A 3 GHz signal is not going to like travelling far on open wires.

If you can arrange that the CAT 5 wire just extends the ports centre pin to a location that you can get at inside the chassis, that should be a nice short length. I think a chassis side rail obscures the port so you just need to place your wire so that it gets around that obstruction. The croc clips of the screened frequency counter cable just connects to the extended centre connection of the port and the metal module case.

Time for bed now as its 02:00 here in the UK.

Best Wishes

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 07, 2016, 02:03:28 am
2:00 AM... I wasn't expecting to hear from you till tomorrow.

I will run out tomorrow morning and try to find a BNC to alagator. I know we have some at work but I won't be able to grab those till Monday.

Stay tuned
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 07, 2016, 02:07:52 pm
I just took another look at your pictures. You need to use the 500Mhz to 20 GHz input on your frequency counter and not the BNC input that only goes up to 500MHz maximum.

The signal you are monitoring is over 3GHz.

Your test lead will need the correct connector for the GHz input on your counter.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 07, 2016, 02:09:26 pm
Fraiser,

I was not getting any signal at that range, so I decided to try to 500 range and that is where I was getting the readings.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 07, 2016, 02:13:26 pm
Likely due to more sensitivity on the lower range and picking up random RF from the environment. I see the high range is fitted with a BNC connector as well so you can buy a BNC to croc clip or BNC to grabber coaxial lead. Always a useful lead to have and it can be used with your 3132 when you get it working.

Fraser

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 07, 2016, 02:16:31 pm
Ive been looking online for some place local to grab one today but my local electronics store in town is closed on Sunday and Radio Shack doesn't seem to have them.

Im gonna try to grad one off a co-worker and if not I'll grab one from work.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 07, 2016, 06:07:31 pm
Fraser,

With the lack of BNG to Alligator, I decided to get creative.

As I looked inside the chassis it seems that I could remove the "divider" from the inside, therefore giving me access to that port that we are trying to monitor.

After taking off the 6 screws on the bottom, then the face plate to reveal 6 more I was able to take it out and hook right up to it (just barely because of the length of my BNC). 

Either way it worked and I am getting a Freq of around 3.8 Ghz.

Please see attached pics and let me know your thoughts.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 07, 2016, 06:31:52 pm
For some reason when I upload the 2nd pic it always shows ends up upside down.. Sorry
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 07, 2016, 07:58:15 pm
Sadly that is not good news. The frequency should be exactly 3840MHz. You frequency is almost 2MHZ out. Which is significant in the 2nd stage of down conversion in the 3132.

I am suspicious of the 0V reading on the PLL 2nd LO control line. It should be trying to bring the frequency to exactly 3840MHz and definitely not 0V.

I believe you have a problem on the 2nd LO PLL or its control line drive to the associated VCO. The reason it is sat almost on frequency is that my simple alignment procedure sets the frequency with 10.3V on the control point of the Varicap diodes. The VCO should then be on the correct frequency when the control line drops to around 0V, which is the PLL control voltage centre point. If you just force the varicap diode control input to 0V it will still be pretty close to core t but it is not under PLL control.

OK, you read 10.3V on the varicap control point so the wiring from the Varicap diodes to the PLL is not shorted. It could be a fault in the control line driver. It would be interesting to monitor the frequency on the monitoring port to see if it drifts as the VCO warms up. If it does not, it would appear the PLL is active but holding the wrong frequency. I would expect you to see frequency drift though, as I think your PLL is at fault here.

Diagnosing the fault in the PLL really needs a good understanding of its chips and a schematic to identify appropriate test points. The alternative is to reverse engineer it and create a schematic for that part of the circuit. I regret I cannot help on the schematic front.

You may be facing quite a challenge here. How about your colleague who has worked on SA repair helping you ?

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 07, 2016, 08:42:45 pm
So I'm not confident in my 0v reading as I was unable to take a reading where your procedure called for.

I was thinking of trying to retake that reading now that I don't have the divider in the way by leaving the cover off of the RF board and connecting directly to the connector that I was applying the 11.3v to (I assume that is the point that you want the reading from correct)?

I just don't know how much error I will introduce to the circuit with the cover off. And I also don't know of any other location to try to take that reading properly.

What are your thought on that?

Also I was never able to dial in to the 3805 using your procedure. Do you think that might be why I am off by 2Ghz?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 07, 2016, 09:09:08 pm
Ok, to answer your question in order

1. The point that you are measuring for the 10.3 V reading during alignment is the control line from the PLL. The 11.3V supply point is not the same and would tell you only that the correct supply was present on the VCO.

2. If you cam confirm zero ohms between the Varicap diodes control voltage point and any point on the route back to the PLL board, that will give you a place to measure the control voltage with the covers on.

3. Do not operate the module with its cover off. It will cause all manner of issues including detuning the VCO.

4. Your present reading is off by 2MHz and not 2GHz. You should aim to be within plus or minus 1MHz of 3805MHz in my procedure, but that is just to get the PLL running with its full positive and negative capability. IIRC the PLL canoe ally pull the VCO plus or minus 20MHz. If you set the frequency to 3810MHz, the LL will still bring the VCO onto frequency but with less further adjustment available to compensate for thermal drift. It will only have 15MHz of PLL adjustment left.


Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 08, 2016, 02:36:19 pm
Fraser,

I'm not sure if this is what you are referring to in you #4 statement but...

What if I take another reading as the unit sits in the chassis and make a note of the Freq.

Remove the unit, and perform your procedure, but instead of trying to lock in the 3805 I adjust the "trim" to offset the reading that I am getting with the module installed?

For example say I still get a reading of 3838 with the unit installed in the chassis. But when I remove it and start your adjustment procedure I am getting 3767. Should I just try to adjust the module up another 2Mhz to 3769 and assume that it will correlate to another 2Mhz once it is install again? Is it worth a show?

Also should I be getting 3805 or 3840 when the units is in the chassis? I'm confused because I was adjusting for 3805 but you were expecting to see 3840 in the last post. Maybe that is correct but I just wanted to make sure.

Am I making sense?

Also, going back a few posts, I left the unit running and went back to it a few times over 45 min and it did not seem to drift from that last point of 3838.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 08, 2016, 06:37:49 pm
OK let's see if I can explain.

The alignment procedure I produced sets the VCO dielectric trimmer with the PLL inoperative. The frequency is set to 3805MHz as the Varicap diodes settle with 10.3v on the VCO control line.

Once the covers are fitted and the module is back in the SA, the PLL changes the voltage on the control line to approx 0V. At this voltage the VCO is running at its correct frequency of 3840MHz and is trimmed to ex actly that frequency by the PLL.

Do not set up the VCO to another frequency as that will not help your situation. The PLL can normally work perfectly well when the VCO is aligned as I have detailed. I spent a lot of time testing the alignment procedure as I had several modules to repair. The lack of a cover on the module does effect the frequency of VCO oscillation so my procedure takes account of this for you.

An important question..... How sure are you that the frequency counter is accurate ? If it is not calibrated or checked against a known good microwave frequency, it cannot be trusted.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 08, 2016, 06:59:34 pm
Ok... I think I get it now... assuming I am close to that 3805 when applying 11.3V to the circuit (using your adjustment procedure), it should automatically adjust the voltage to lock in the Freq when it is all put back together. Is that right?

Keep in mind I was never able to get that 3805, and I don't know if based on what you saw I was able to get close enough.

With that said the one thing that I did notice when monitoring the DC power supply with my DMM (when I was applying the 11.3V called out in your adjustment procedure) is that the Voltage seemed to drift. So I wonder if that might be causing an issue and if i should let things sit and settle for a while before attempting anything.

I work for a calibration lab so I know Freq Counter (HP 5343A) is calibrated.

The last calibration was on 9/17/15 and using our GPS Reference Standard it read exactly 10Ghz. The tollerance is +/-.58 Hz for this particular.

The Power Supply (HP 6205B) was last calibrated on 10/6/15 and was also in spec.

I was using just a cheep Ideal DMM so it is possible that is where I was getting the drift. I will try to confirm this when I get home tonight.

(again sorry for going around in circles but I just want to make sure I am not missing something simple)

If I am applying 11.3V to the circuit and I am able to tune it to 3805Mhz then i should be getting a reading 10.3 between the Vericaps? Do I have that correct?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 08, 2016, 07:18:44 pm
Fraser,

Also, any idea what type of current the circuit will draw during adjustment? I wonder if my power supply is underrated.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 08, 2016, 07:55:50 pm
If you have 11.3v at the input to the PCB your PSU is not current limiting and fine for the task. I do not recall how much current is drawn but it wasn't much.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 08, 2016, 11:27:51 pm
Fraser,

So I hooked everything back up to give the adjustment another shot and same this as before, I can't seem to hit that 3805 I can get to 3767.

I then decided to see how much current it is pulling off the power supply when feeding the 11.3 v and I am maxing out the power supply to .75 amps.

Should I try a more powerful supply?

Thoughts?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 08, 2016, 11:44:09 pm
Just for fun I hooked up to the 2 output in my PS.

This time I was only drawing around .5 amps but as soon as I hooked the RF board up my voltage dropped to like 6 v (on my Dmm that I am using to monitor) I then disconnected the Dmm from the PS and took a reading at the varicap and I was getting 9.4v and then 9.7 on the PS.

I'm starting to think I have a PS problem.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 12:03:17 am
By applying power to the 2nd VCO supply rail you will be providing power to other circuits and components on that same supply rail, even though they are not actually doing anything useful. 0.75A is not an unreasonable current draw.

If you cannot get the VCO to 3805MHz then there is a problem with its tuning range that needs investigation. The dielectric tuning 'plate' needs to be very carefully moved through its full arc of travel whilst watching the frequency on the counter. There should be ore than one part of the arc where it approaches the correct 3805MHz. It can be pretty fiddly to get right. The greatest error in the set frequency that I would accept would be 3804MHz to 3806MHz. Anything further away from 3805MHz is forcing the PLL too far off its centre setting and thermal drift could cause issues later.

Sorry that I missed the large error in the frequency of the VCO earlier. Too many jobs on the go at once and late nights :)

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 09, 2016, 12:55:23 am
no worries.

Yeah I do notice that as I twist it the freq will cycle to a low freq back to a high and at about ~180deg it will get close to the same reading but never as high as the 3805. I think when I took the pics at 3797 that was the closest I ever got to 3805.

I still cant figure out why on the first PS output I max out the current then on the second I only draw half the current but the voltage drops.

Is it reasonable to assume that if I am not supplying the proper voltage and required amperage that I would never achieve the 3805?

Either way I am trying to get my hands on another power supply to try tomorrow, I will keep you posted. 
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 12:06:22 pm
If you can apply 11.3V the PSU is OK. Sounds like your second PSU channel is sick.

It is a problem that you cannot achieve 3805MHz. Such would suggest an issue in the VCO. You could have a failed Varicap diode or other tuning component. To prove this I would isolate the Varicap diode control line and bench test the VCO's tuning range. It's tuning range should be approximately 40MHz. Sadly IIRC this is not such a simple test to configure as the Varicap diodes sit across a split supply with the control line moving plus and minus around 0V. It would need some careful configuration to avoid potential damage to other circuits.

This is becoming a more complex job I am sorry to say. A problem in the VCO is challenging due to its 3GHz operating frequency. With the greatest of regret I do not have the time to write a full test sequence and draw the schematic so that we can isolate the cause of the problem. If you were in the UK I would suggest you send the module to me and I would repair it for you. Sadly postage costs from your location would make such an expensive option.

Sorry that I cannot be of greater assistance to you on this problem. Your colleague who has worked on SA repair before may be able to help you isolate the problem further. I recommend that the schematic for the VCO be drawn so that all potential causes of the frequency error may be identified. The Varicap diodes are the first place I would suspect until I proved that they presented the correct capacitance range to the VCO. There is also the matter of the VCO control line from the PLL appearing to be sat at exactly 0V. That is not right at all. If the VCO is not producing 3840 MHz the control line should be a long way off 0V as it attempts to pull the VCO onto the correct frequency.

Whilst writing this message, I have had another thought and relatively easy test for you. ...........

It would be worth checking that the positive and negative supply rails to the Varicap diodes are present. Working from memory, there should be +12v on one end of the pair and -12V on the other end. It is possible, just possible you have lost the -12V rail or connection so the PLL can only drive the control line to 0V and not negative, as required. I say this because I think the PLL should cope with an initial setting of 3797Mhz.

You need to do some continuity tests to establish where the dual supply rails to the Varicap diodes comes from. Hopefully you can find a convenient point to attach some wires so that the module may be inserted into the chassis and switched on. All power supply rails will then be provided by the SA chassis for you. Check that the voltages are present. I will need to check my notes on the power supply rails used on the 2nd VCO it was either +-12V or +-20V. Whichever, it should be symmetrical around 0V.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 12:12:15 pm
My alignment guide contains all the details. The maximum p.d. across the Varicap diodes is 24V. This is across split power rails of -12V and +12V with the PLL moving the control line between these two limits. You could well have lost you -12V rail at the PLL VCO Varicap diode driver. Definitely worth checking.

My memory also failed me on the VCO spec. It can be swung plus and minus 40MHz around its centre frequency so has a range of 80MHz.
With this range, the PLL should definitely be able to cope with your 3797MHz centre frequency. All this will mean is that the PLL will have less tuning range available to it in one direction. The more I think about this, the more I think you have lost your -12V rail at the VCO control line driver.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 01:03:46 pm
I feel like I am missing something here. Working from memory is never a great idea. I will spend some time looking at the VCO pictures I took whilst working on these modules to determine the exact topology. Once I have an understanding of that, I can advise on how it is supposed to operate. The problem at the moment for me is that I designed my alignment process around just supplying 11.3V to the VCO. The Varicap diode control line settles at 10.3V naturally so I worked with that to select the required frequency setting for the dielectric trimmer. It's a pretty nasty alignment technique but it's easy to do with the cover removed and it works well. The KISS principle at work.

However, when a fault is present we need a better understanding of what is happening in the VCO as the +12V and -12V rails are not present during my alignment procedure.

This is something I will have to study in order to make helpful comment.

You can however proceed with checking the voltages that are being applied to either end of the Varicap diode pair and also the Supply rails to the PLL driver chip that drives the Varicap diode control line.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 09, 2016, 01:08:27 pm
I will do that today and let you know what happens. Thank you again for all your help.

I was able to get my hands on a Tek 2520 Programmable Power Supply so I am interested to see if that makes any difference.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 01:30:46 pm
Yep, as I suspected, My memory is failing me. Having looked at the picture you provided of your VCO tuning, it is not as I thought. Please await an update from me and tests that need to be done.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 02:09:55 pm
OK I am having a feeling of Deja-vu when looking at the VCO. I must have reverse engineered it previously. I shall look for any notes that I still have and if necessary I will redraw the schematic. I have little time so the result will be hand drawn and functional rather than pretty :)

More comment as soon as I am done looking at this circuit.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 09, 2016, 02:19:25 pm
Not a problem, let me know if any additional pictures on my end might help.

Are you thinking that the adjustment procedure does not apply to this particular revision or are you trying to advise on additional troubleshooting procedures?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 02:24:42 pm
No, the adjustment procedure still works fine. It is the cause of the failure to lock a at 3840MHz that I am investigating. My line of thinking is that the 0v you are seeing on the control line is because the PLL has lost half its tuning voltage range. I suspect the -12V rail has gone but need to prove it to myself.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 09, 2016, 02:30:46 pm
OK.

Also, just as a side note (in case you don't have pics of the board you worked on)... I only saw 1 of those pass through pins come through to the other side that would allow access to take a measurements on while the cover is on the board and it is installed in the chassis.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 03:55:10 pm
No worries,

I am drawing the VCO right now. It s a bit different to how I remembered it but I am already suspicious that the -12V rail or missing from the LM324 that drives the Varicap diodes. Either that or the LM324 has failed.

It should be clearer once I post the schematic

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 04:56:32 pm
Just for info if anyone else works on one of these R3132 VCO's ....... the design was changed in older and newer versions so the schematics, though similar, are crucially different in one particular area. Namely the injection point of the PLL control voltage ! The older model had a design flaw and when they fixed that they moved the PLL control voltage connection to the varicap diodes and reversed the diodes on the PCB. This is why I have previously visited this VCO.... it obviously had me scratching my head last time I worked on one of these. The good news is that I have a photographic record of both versions from which to work.

All good fun.

I will post the simplified schematics for both to aid others in fault finding. The VCO is very simple in DC terms so we should be able to sort this issue out.

I am off to the VETs now, so will complete this later. (The vets isn't for me  ;D ....the cats need their annual inoculations)

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 09, 2016, 10:31:20 pm
OK all done  :)

Attached are the simple style schematics for the two versions of 2nd Local Oscillator found in the R3132. I include the very much simplified DC model to the right of the schematic. Your module is a Type 1 early version.

As can be seen, changes have been made around the area of the varicap diodes in the Type 2 version. The changes have improved the design but the simple alignment procedure that I wrote applies to both versions in all respects except where you measure the control voltage on the varicap diodes..

In both versions, the Varicap diodes are in series with the VCO resonant circuit and this is how they influence the oscillation frequency of the VCO. In purely DC terms however, the two diodes are in parallel and the potential difference across them is created by tying one end of the parallel pair to +11.3V whilst the other end is connected to the Control Voltage (CV) line coming from the Phase Locked Loop (PLL) PCB. The PLL produces a voltage at its output in the range -12V to +12V. As such it is capable of providing ~0V to ~23V across the varicap diode pair.

If CV -12V then the p.d. to +11.3V on the other end of the varicap diodes is 23.3V
If CV +12V then the p.d. to +11.3V on the other end of the varicap diodes is 0.7V (but forward bias on varicap)

In my alignment procedure the CV pin settles at +10.3V and the VCO produces 3805MHz. When the PLL is active, the CV line drops to around 0V, which is its mid point of output capability, and the VCO rises in frequency to its specified 3840MHz. In the alignment phase, the p.d across the two Varicap diodes is 1V. When the module is reinserted into the chassis and the PLL is active, the p.d across the varicap diodes increases to approximately 11.3V.

Now if we consider the loss of the -12V rail to the PLL output LM324 chip we have the following potential scenario........

As stated, when the module is aligned in the manner that I detailed it has no PLL control. When the PLL is active it applies approximately 0V to the CV pin, the VCO should be pretty much on frequency at 3840MHz. If however the alignment phase has proven that the VCO cannot be set at 3805MHz, due to component tolerances in the VCO circuit, we may have to settle for something near to that frequency.

The PLL can swing the VCO through a range of -40MHz to +40MHz around its set centre frequency. 3805MHz is the ideal alignment frequency but less than 10MHz either way will not be significant in most cases. That would provide an acceptable alignment frequency range of 3795MHz to 3815MHz. It may even be acceptable to use a frequency as much as 20MHz away from ideal, but this does limit the PLL's lock capability in one frequency drift direction as it is already compensating for the alignment error. This is already explained in my alignment guide.

We know that an alignment frequency of 3805MHz is optimal as when the PLL is active it only needs to apply approximately 0V to the CV line to gain lock at 3840MHz. It is therefore pretty much in the centre of its control range. If however we could only achieve 3790MHz during the alignment, the frequency will be too low and the PLL will compensate by applying the required voltage to the CV line. In this example it would actually apply a negative voltage on the CV line in order to generate  greater potential difference across the two varicap diodes. If the -12V power rail is not present at the LM324 on the PLL output, a negative voltage cannot be applied to the CV line. The result will be a PLL trying to pull the VCO onto frequency and failing to do so because it cannot create the required p.d across the varicap diodes. It will do its best though and try to drive the LM324 for negative output. The output will sit at 0V however as the LM324 cannot supply what it does not have, i.e a negative potential.

Well this is my present theory on what has gone wrong but as I do not have the module in front of me, you will need to do some testing to prove whether I am right or wrong about this. I am very tired right now so regret I cannot help further for the moment.

Fraser

UPDATE : PLEASE READ

It has become apparent to me that the type 1 module may differ to the type 2 module in ways that I cannot capture as I do not have a type 1 module available to test. The simple schematics that I have drawn come from my type 2 module repair notes, and photographic records of both module types. Please treat these schematics with caution and use them as guidance only as their content IS NOT guaranteed accurate !

Caution should also be exercised when using my simple alignment procedure on type 1 modules as there Are differences in the type 1 module PCB. The principal remains valid however.

Thank You

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 10, 2016, 12:32:13 am
Some pictures of the second Local Oscillator VCO and associated PLL PCB.

There are two different examples of the Type 2 VCO and one of the type 1 VCO.

Note that the Type 1 VCO has been mauled at some time by the service agent. The dielectric trimmer 'wiper' has been removed and they have used an SMD resistor to act as a stripline tuning element on the striplines. Nasty workmanship. From this evidence it would appear that Type 1 VCO's may be hard to get within centre frequency spec using just the dielectric trimmer wiper. I checked the VCO alignment and it was acceptable. The module was working fine and that SA had a corrupted Firmware CF card. Out of five units, this was the only one that was without its dielectric wiper.

I have previously taken a picture of me probing an output pin on an LM324 located on the PLL PCB. I can only assume that this was the CV line going to the Varicap diodes. This is a later type PLL and may not be identical to the earlier version. LM324 pinout attached. It is a single or dual supply rail device. In the PLL it should be a dual supply rail configuration in order to swing the output from  -12V to +12V under PLL control.

Hope this helps.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 10, 2016, 12:52:39 am
The PLL PCB is well labelled and has test points for both the +12V and -12V rails.

I attach a close up picture.

TP10 is +12.6V
TP11 is  -12.6V

The presence of these voltages at these test points does not prove that the voltage is reaching the PLL CV line output driver. You can check continuity between the test point and its associated LM324 power supply pin with the module on the bench. Then solder a temporary thin test wire to each test point and measure the voltage with respect to chassis whilst the module is in the chassis and powered.

There remains the possibility that the LM324 is faulty so the presence of the correct voltage at its supply pins does not mean that it is working correctly. In the attached LM324 op-amp equivalent circuit, Q13 failing open-circuit would cause the loss of the negative voltage swing at the output. We will consider next moves after you have tested the supply rails.

I almost forgot, my modules had a current draw of approximately 200mA on the 11.3V supply when doing the alignment procedure with the module out of the chassis. Yours appears to be drawing significantly more current. That may need further investigation.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 10, 2016, 01:22:25 am
One final comment before bed.....

On my simple schematics I have shown the three components that are across the Varicap diodes in your Type 1 module as inductors, but in truth I have never tested them in order identify whether they are inductors or possibly even diodes. The link is essential to connect the CV line to both varicap diodes. Inductors would normally make a mess of the tuning. They may be diodes. Three in series drops voltage but lowers their total capacitance. The diode test mode on a multimeter may resolve this unknown but I doubt it has anything to do with your problem.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 10, 2016, 03:10:58 am
Fraser,

I can only hope that all your efforts will end up helping someone other than me some day...

I have to be honest that without a procedure similar your adjustment procedure I worry that this is over my head. Granted as I said before, at this point I have nothing to loose at this point because either way I don't have a working unit.

As I mentioned in an earlier post I was able to get my hands on another power supply today and I wanted to let you know what happened with that...

As it turns out when 11.3 V are applied to the point specified in your adjustment procedure the unit was drawing .7 amps, so just outside the max of the unit I was using previously.

Unfortunately with this power supply I had the same results of not being able to achieve the 3805.

At this point i did my best to take some of the measurements you were referring to in your previous posts, and this is what I ended up with...

with 11.3 V applied
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 10, 2016, 01:47:23 pm
Hiya,

With great regret I have to stop this remote diagnosis here. This is not because I do not want to help, but rather my concern that I do not have the older Type1 module in front of me and it could have significant differences in its design to those that I have worked on. The increase in current from what is expected, to an abnormal draw could be a failed component or it could be because of a difference in module design. This makes proceeding without the ability to take reference measurements on a good SA too risky.

I am sorry that this little journey into your R3132 must come to an end here but it would be better to find someone local who can repair the unit for you. It is likely a simple fault and worth the effort.

For other readers..... Please consider the schematic for the Type 1 module suspect, especially the voltages as I did not have those on record from when I worked on an older generation of module. The newer modules have an additional 390 Ohm power resistor which may be significant. Without further investigation I can not be certain of its function. Sadly neither my time nor my energy levels permit such an investigation.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 10, 2016, 05:59:41 pm
Having given this situation some thought today, I am concerned that the type 1 module has some significant differences to the type 2 that I have worked on in greater detail. Though I do not recall any power supply differences I believe that the type 2 module contains a 390 Ohm power resistor as a dropper for the MMIC's. The type 1 module has no such resistor and this may be the reason for the unusually high 700mA  current draw when the VCO is powered from 11.3V. Whilst the MMICs have survived, this is not a good idea.

I do not have a type 1 module to carry out tests on so cannot risk providing further comment on the VCO circuit or its power supply arrangement.

I have added a note to my simple schematics posting. These schematics were produced from repair notes produced when I repaired 5 R3132 analysers. I also had detailed photographs of the two module types. My notes suggest both have the VCO running off of 11.3V but I have no way to prove this.

This has been an interesting investigation and I have not minded spending some time on it, drawing schematics etc, but it also highlights the risks involved in remote diagnostics and equipment version differences.

I sincerely hope that this sick R3132 is eventually repaired. It is likely to be a simple fault and they are worth the effort. I paid GBP600 for mine so they are not cheap.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 11, 2016, 02:34:09 am
Fraser,

Quick question for you, hopefully.

Do you have any idea how I could go about getting replacement vericap? I assume the have specific sizes and ratings.

For some reason today I decided to remove the dielectric swiper to see what happened and when I did the unit put out a freq of 3805-3804 consistently. I actually powered down the supply a few time and each time it settled in (this was while supplying 11.3V).

I wondered if that might have solved my issue but when I put it back together it hadn't.

So I tried to confirm the voltage on the vericaps and I was getting the expected voltage between the two vericaps and on one end, but the other end had no voltage. I figured it might be worth trying to replace them.

Thanks
 
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 11, 2016, 12:03:58 pm
Having slept on this I do not want to walk away from you on this problem. It is very hard doing this sort of diagnostics remotely though.

I have decided to continue offering advice, at least until I run out of ideas.

I have studied the Type 1 and type 2 pictures and believe that there is a significant difference that we must confirm before proceeding.

From what I can see, the Type 2 module uses 390 ,Ohm voltage dropper resistor in series with the 11.3V supply to the VCO. This is supported by the fact that only 34 Ohms is present in the MMIC bias supply lines. 34 Ohms is way too low for 11V operation. I would expect at least 300 Ohms.

The Type 1 module has no visible 390 Ohm resistor. I originally thought it was under the PCB but that is an assumption on my part.

If we assume for a minute that the Type 1 module uses a lower supply voltage, that would explain the excess current draw at 11.3V. The question is, what should its supply voltage bevwhen bench testing the VCO ?

My units had a 200mA current draw so you could set the current  limit on your PSU for 200mA, set the voltage to 3V, connect to the VCO power rail, and slowly increase the voltage. The voltage at which the current limiter kicks in will be very close to the normal operating voltage. Very rough but if it is near 5V then that will very likely be the supply voltage used.

As a second and important confirmation of this. Connect a long wire to the power supply pin of the VCO where you have been connecting your PSU. Reinsert the module into the chassis without its lid. Switch on the analyzer and measure the voltage between the wire and the shell of the module. That will provide the operating voltage that we must use.

OK, with regard to your latest weird voltage readings. This is unlikely to be Varicap failure. Look at my schematic for a type 1 module. The mid point of the varicap is the supply rail. One outer point is connected to the PLL control line directly but the other is connected to the PLL control line via those 3 components that loop around the pair of varicaps. There could be an intermittent connection at work here.

Before we make any assumptions we need to establish some facts and be logical in our approach. The correct supply voltage for tests is crucial so let's sort that out first. More tests to follow.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 11, 2016, 12:36:59 pm
Fraser,

Just when you think you are done... I drag you back in... (haha, I really do appreciate it thought)

Its funny you mention connecting a "long power wire" to the supply pin and leaving the cover off, because that is exactly what I did last night. The voltage  was 6.13 V being supplied to the module while inserted and powered on.

You are also correct that at 6.13 V is draws ~ .2 A on the PS, its actually a little higher than that but it is in the 2's. I do have a picture I took from a few days back and at 5.1 V if was drawing 2.14 so it is not too much more than that, I can get an exact answer tonight.

Do you want me to re-attempt the adjustment procedure at 6.13 v?  I'm pretty sure I did and was still unable to get 3805, but I am happy to try again.

Is it possible that the dielectric sweeper arm's characteristics can change over time? I'm only asking because I noticed that I tend to get my highest freq output when it is removed completely. However if all it is, is blank piece of PCB board I can try to make a replacement as I have access to a wood cutting CNC that may cut out a replacement piece. (just a thought)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 11, 2016, 03:23:47 pm
Hiya,

I hate to admit defeat if a little more effort could bring success !

The dielectric trimmer including the PCB on which the VCO is mounted can change its characteristics over time but we have to work with it as replacement is not an option.

Remember the picture I posted of a type 1 module that was without its dielectric trimmer ? Your experience may be the reason for such an extreme measure. Let us not go down that route yet though.

OK, this where we are at......

1. We now know that the VCO in a type q module runs at 6V and not 11.3 V
2. The VCO supply also applies the Varicap diodes so they will have only 6V on them rather than 11V which is significant as it effects the control voltage range
3. We do not know the control voltage range of the PLL as it will be different to the Type 2 module.
4. The Varicap diodes would normally have around 20 to 30V maximum p.d. for a decent tuning range if all of that range is to be available. The type 2 module has a maximum p.d. Across the diodes or around 24V (-12V to +11.3V)
5. If we for a moment assume the same 24V maximum p.d. Across the the varicaps used in the type 1 module, the PLL control voltage range will be -18V to +6V with a mid point of -6V.

That gives us the following

-18V to +6V provides a 24V p.d across the Varicap diodes
+6V to +6V provides a p.d. Of zero across the Varicap diodes.

The PLL adjusts the control voltage around a mid point in its range which would be -6V as opposed to the 0V that I used on the type 2 module. This is different because of the lower supply voltage on the Varicap diodes. Everything has shifted down by 6V.

Hope you are following me on this.

6. It is possible that the type 1 module has a much smaller VCO tuning range and only uses part of the Varicap diode available capacitance range. That would potentially mean that a type 1 module has a 6V supply to the varicaps and its control voltage is symmetrical around 0V. Such would mean that the control voltage has a range from -6V to +6V with a mid point of 0V as with the type 2 module. This would mean the VCO control range is only half that of the type 2 as maximum p.d. Across the varicaps is only 12V instead of 24V.

7. The best way to determine the control voltage range of the PLL is to trace the CV line back to the PLL PCB and the driver chip using simple continuity checks. Once the driver chip has been found the voltages on its power pins may be measured in the same way that the VCO supply voltage was checked....a long test wire. If we see +6V and -18V we know that we have a 24V range and if we see +6V and -6V we know we have a 12V tuning range. Sadly, if your u it has a failed negative voltage rail, we may not see the expected negative voltage reading. We will cross that bridge if we come to it.

8. The frequency to which the VCO is aligned will very much depend upon the tuning range of the VCO and p.d across the Varicap diodes at the time it is set up. We shall deal with that when we have the facts regarding the tuning range.

9. It is a possibility that there is an intermittent open circuit in the connection between the extreme ends of the Varicap diodes. The connection between these two points is made using the three unidentifiec components mounted in an arc around the two diodes. This connection delivers the 6V to the leftmost diode so if that connection fails, that diode can no longer be biased and that will ruin the tuning range by halving it and also causing an error during alignment. The identity of the three small components would be useful. I shall detail how to test them and the continuity of the supply chain in a separate message. This will follow later.

Fraser

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 12, 2016, 04:52:20 pm
Fraser,

Sorry for the delay, I don't know if it was the case for you but for my the site was down most of the day yesterday so I was unable to post anything. As a result I haven't started on your last post either.

I assume that the most important thing at this point is to jump down to #7 as I think we need to know the actual voltage we are working with correct?

The way I was able to confirm the 6V was to solder to that pin with the blue wire come off of it in the area of the LO2. Do you think I will be making this measurement off of a similar pin or off of a IC ?

It is around lunch time here on the East Coast so if you have a chance to replay before I get home I will proceed accordingly.

Also, regarding #9 it seems i did have a bit of a bad solder joint across that "unspecified" component. I did a quick solder job and i am now getting voltage on both ends of the vericaps and in the middle again.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 14, 2016, 04:01:31 pm
Fraser,

Not sure if this is good news or bad news for my situation...

I decided to go down at start fresh again to make sure I wasn't missing anything obvious.

I first connected a lead to the "pin" to confirm a 6.2 V supply when the unit is in the chassis, this is confirmed.

I then removed it and applied 6.2 V form my supply and although I was unable to lock in the 3805 when the sweeper installed (I could get as close of 3795), as soon as I removed it I immediately go 3805 (even powered on and off a few time and it always came right back).

I figured I would put it back in the chassis and power it to up see what freq was coming out of the set port when it was installed. These reading were all over the place from ~4000 down to ~2000. However as soon as I tried to run the self cal it would go right to 3840, every time.

Unless I missed something I believe these are the 2 freq we should be expecting in this situation, correct?

Can you think of anything stupid/simple i might be missing at this point.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 14, 2016, 05:57:04 pm
Hi,

Sorry I have been occupied on some other work but having just seen your post things are looking up. The most important thing is to have 3840 MHz when the Analyser is running. We do need to check the voltage on the PLL control line to establish what voltage is present. That will give some idea of the PLL state.

With the frequency counter showing 3840 MHz does the Spectrum Analyser still indicate a fault when self test is run, if so, is it the same as previously ?

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 14, 2016, 07:57:55 pm

***I was going to post to you in response to your question, however when I went to confirm the measurements I spent some more time messing around so this post is  a 2 parter. Hopefully some of it is useful***

PART 1:

The voltage on the PLL control is pretty consistent at 6.2V while installed in the chassis, +/- .02V (I am measuring this via a wire I soldered to the post).

While in the chassis I was not getting 3840 Mhz exactly all the time, however it was pretty close it only fluctuated by 20Mhz or so . Every time I initiate the "Self Cal", at that moment I hear a "click" noise, the unit would lock on to 3840.

Yes, even though I am seeing 3840 I still get Fail on the Self Test and also the 807 error on the Self Cal.

PART 2: (some other things I did)

I decided while I was down there I would take the lead wire off and put the cover back on to see what happened. I even took the opposite side of the module apart to see if there was a spot to supply power through the passthrough and there is not.

When the unit is installed in the chassis and the cover is on I no longer got the 3840 it was more like 3856, plus when I ran the Self Cal that Freq would not change like it did with the cover off. For some reason it would just stay at 3856 and not change. (Now I cant think of a reason why with would happen with the cover off and not on)

So just for the fun of it I removed it again, put the sweeper back on and adjusted an offset of 16 Mhz so that when I reinstalled it into the chassis I was getting 3840. (I had to set the "Adjusted Freq" to 3793 by the way)

However even when I was able to dial in the 3840 in this manner it still didn't work.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 14, 2016, 08:28:24 pm
Two comments.

The PLL control voltage is not the supply to the VCO. I am. Nor certain that you are monitoring the correct point for the PLL control voltage. You can actually monitor the control voltage on the outer pins of either of the Varicap diodes. The point where they are connected together will always be 6V. The problem with monitoring the voltage on the Varicap diode is that you will adversely effect the tuning of the VCO. That is why we really need to find the point where the PLL control line leaves the metal chassis and passes up to the PLL PCB. Monitoring at that point does not adversely effect the VCO tuning.

The PLL control line has a 15K Ohm resistor in series with it at the Varicap diode so any continuity checks between the Varicap diode ends and the PLL PCB control line output will read 15K when you have continuity. I will have to draw the test points on the VCO diagram for you and that will be a point that avoids the 15K resistor.

All your symptoms suggest to me that the Phase Locked Loop is not controlling the VCO. We are back to the likelihood that the PLL VCO control line output is open circuit, missing a supply rail or the driver chip is faulty.

Sadly whilst the PLL is not locked, you will never get a calibration pass.

I am a bit busy this evening so will write again tomorrow.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 14, 2016, 08:37:29 pm
While you await further comment from me you could assist a great deal by providing the following photographs.

1. Picture of the meal chassis on the opposite side to the VCO and with the PLL board removed. I wan t to see if I can track down the PLL control line visually. if there is a Connector that plugs into the PLL board and is connected to several places on the chassis below, please provide photographs of all these connection points...... One will be the PLL control line !

2. Detailed pictures (several please) of the PLL PCB, both sides including overall shots and close up, say breaking the PCB into three sections. I may be able to identify the PLL and its driver if the pictures are good enough.

3. If able, please also photograph the VCO side of the chassis, with all covers removed so that I can look for then PLL control path.

If a particular picture is of interest I will provide my email address so that you can send me a higher resolution image. Standard 640x480 is OK for initial viewing on this forum.

Best Wishes

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 14, 2016, 11:47:30 pm
Fraser,

I hope these pics are what you are looking for. Even though I resized them I could not fit more than 3 on a post so I put them on Postimage to share them. The link is here  [url]http://postimg.org/gallery/22m0qrrpq/806c6b82//[url]

I took a single shot of each board, then 3 closeups, then a panorama.

I dismantled and took picks of all boards/covers on the opposite side (opposite side from where we have been working) as well. There were a total of 3 covers that I removed on that side.

Also as a side note is seems that all the pass-throughs from the side with the adjustment are coming throughs, but soldered directly to the circuit boards.

Please let me know if I missed something.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 17, 2016, 11:59:29 pm
Fraser,

(Please know I have zero intention of rushing you along)

I just wanted to confirm you were able to see the pictures I put on Postimage.

If you have a chance please confirm.

Thanks.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 18, 2016, 02:33:47 am
Hi, yes no problem. Pictures can be seen.

I am a bit buried in work at the moment but will come back on this as soon as possible.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 18, 2016, 02:34:58 am
Please, no rush at all.

I just wanted to confirm.

Thank you.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on February 25, 2016, 07:35:48 pm
Be assured, I have not forgotten you. Just a lot on my plate at the moment.

I will be back !

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on February 26, 2016, 12:51:05 am
No worries, I'm in a holding pattern awaiting you instructions.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on March 11, 2016, 06:43:01 pm
Fraser,

Any feedback on how much access you think I will need to the circuit boards?

I still have the unit apart on my bench and I want to put as much back together as possible so I don't lose or accidentally break anything.

Thanks

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: lelandford on April 02, 2016, 03:22:30 am
I have an Advantest R3131 that has the tracking generator hardware installed but does not seem to realize it.

I believe the issue is that the lithium battery which was backing up the realtime clock and a couple of static memory chips failed. 

I replaced the battery and now the fact that it had the TG option is no longer remembered.

I don't know how to restored the option setting in the static memory.

Anyone have any experience with this?

Microlease wants $4K to fix this and thinks it may have to be sent to Japan which is out of the question.

I've looked everywhere for clues as to how to restore the option but no success so far. I've tried all suggestions that I've been given but as I said...no success. There is a Shift 5 and a Shift 9 function that may help but each is asking for a password that I have not been able to crack yet.

Hoping one of you guys holds the key. :)

Thanks,
Leland
K9SDR
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: TheSteve on April 02, 2016, 04:27:57 am
I haven't seen anyone mention they have figured out a way to re-enable the tracking gen after the battery dies - the question has been asked several times. Eventually the right person will be determined enough to disassemble the firmware and figure it out, when they do I hope they share it with everyone.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on April 02, 2016, 10:23:59 am
I posted this before: there is a small button on the CPU board near the rear of the spectrum analyser (you have to remove the rear cover). I had some problems with my R3131 after I replaced the battery. Pressing the button seemed to re-initialise the data in the battery backed-up RAM. It wouldn't surprise me if that procedure also gets the tracking generator working again.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: lelandford on April 08, 2016, 06:50:17 am
nctnico,

I have tried the reset button on the cpu board. Unfortunately it has no effect for re-enabling the tracking generator. :(

I appreciate the suggestion though. I'm open to any other suggestions.

I believe there are option enabling bytes that must be set in the static ram that is backed up by the battery. Unfortunately without a utility running on the R3131 I have no definite idea where those memory bytes reside in the address space and what the code is for enabling it. I'm feeling like the passwords for shift-5 and shift-9 might open up a utility but I have not yet cracked the password for either of those functions. I have tried several published passwords for other Advantest analyzers but none of those seem to work either. Sure wish I could figure it out. I would love to be able to share the answer with everyone else.

Leland
K9SDR
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Wuerstchenhund on April 08, 2016, 08:11:54 am
Silly question: have you asked Advantest if they can help? I don't have much experience with them but sometimes manufacturers are friendly enough to hobbyists to help them (re-)enable options for old gear.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on April 08, 2016, 11:32:50 am
Quote from: lelandford on April 08, 2016, 06:50:17 am
nctnico,

I have tried the reset button on the cpu board. Unfortunately it has no effect for re-enabling the tracking generator. :(
Did you press it long or short? Try pressing it for a couple of seconds AND keep it pressed in during power on. Maybe it takes a longer press or it is only detected during power on.
Your calibration data is likely to dissapear as well. You can check by enabling the 30MHz calibration signal. If it is off then the calibration data has been erased.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 08, 2016, 11:08:13 pm
Hello Guys/Gals,

I am not here to hijack this thread but I do think I may be able to offer some bits of information. Background is that I have recently aquired a R3132 SA and upon checking it out it seemed like there was a Oscillator/PLL issue. I connected and measured the reference output frequency and it was off by about 3MHz (27Mhz ish) and had a all around instability about it, power seemed in the ballpark but not perfect. :scared:

Jump on google and start reading and I find out about the RF VCO aging issue. Sounds likely. I stumbled on this thread and read about jc81382 R3132 and his and Fraser's battle with it. Oddly enough the RF board I have in my R3132 appears identical to jc81382's photos and not like the one in the pictures of Fraser's alignment guide. Since I was going through the same procedure I decided to make a few measurements and post my results here hopefully they will be of some value. I will get some pictures up asap as well.

The first thing I did was open up the RF deck and attach some 28Ga spy wires to the power supply feed-through to the 2nd LO MMIC and another to the PLL feedback (TP501) running to the varicap structure. If you take out one screw holding the RF probe power there is a nice hole to get small wires out. I put everything back together and fired it up. Everything came up just fine and I made these measurements:

MMIC Power: 6.53
PLL Feedback: -9.58

So it appears that this RF board uses 6.5V for the MMIC power supply to the 2nd LO and I am going to guess the tuning range is +/- 9.5V. Yup my VCO needs some adjusting. As a confidence check I did a measurement on the reference signal with a Tek MDO4000 scope with the SA option and I found the R3132 reference to be bang on 30Mhz at -20dBm. I have booked some time next week to go and visit a friend who has a whole room full of SA, sig gens, power meters, and the little bits to connect them all together. He has an Agilent SA that does 6.7Ghz that should help get the VCO tuned up again. I would like to try and get the VCO aligned again so the PLL will lock and then feed in some reference signals and see how the unit is in accuracy department.

I will report back after I give it a go.

Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 09, 2016, 12:15:37 am
Hi RadioAct,

Many thanks for this useful information. Your readings are very helpful.

Sadly I have been well and truly buried in other work so had not made any progress on tracing the PLL control line path to the Varicaps. You have now detailed a way to monitor said control voltage quite easily.

The challenge with setting up the VCO is knowing what frequency to set it to without PLL control active and with the cover off. It might appear to be as simple as 'with 0V on the varicaps the centre frequency may be set' . Sadly the PLL control line does not rest at 0V on the uninstalled module so that would need to be addressed. Also, with the cover removed, the VCO may oscillate at a different frequency to when the cover is on. You can sometimes use aluminium foil to simulate the cover during adjustments but it is fiddly with the dielectric trimmer design.

Tuning the VCO can take a lot of trial and error. I was fortunate enough to have a working module to use as a reference so I knew what the VCO should be set to with the PLL inactive and cover off. Without that I would have likely tied the Varicap diode control line to 0v and set the VCO to near its correct operating frequency. I would then have checked how many MHz the VCO shifted with the cover fitted. Re-adjusted the VCO trimmer to compensate and repeated the whole operation, again and again until the VCO was pretty much set to its most accurate frequency possible with the trimmer. I must warn that the dielectric trimmer is a PITA to set, as small movements can cause large shifts in frequency and the adjustment is not linear.

I may have been too fussy about getting the VCO frequency very accurate as the PLL can pull it onto operational frequency within reasonable limits.

Good luck with your adjustments.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: lelandford on April 09, 2016, 01:46:19 am
Wuerstchenhund...I have contacted Microlease who is the designated Advantest service organization for the US. As I mentioned in a previous post, they are the ones who quoted me $4k to fix it. I can buy another analyzer for that. :) I responded to their quote by telling them my situation and that I am using this analyzer for hobby purposes only and that I would appreciate some information on how I could fix it myself. They did not respond back. I took that to mean they didn't want to bother with me if they could not get $4k out of me. I have not tried to contact Advantest directly in Japan, so maybe I'll try that next.

nctnico...Yeah I have tried holding it down all during the power up process and also a short press. Both seem to simply reset the processor and unfortunately neither fixes it.

Thanks,
Leland
K9SDR
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 09, 2016, 07:15:14 am
Thanks for the info Fraser.

I am expecting a fussy alignment process with everything and anything affecting the oscillator while the lid is open. Just adding the wire made a noticeable change to the oscillator, it's now closer to 2MHz off then 3MHz like when I started.

As for the VCO feedback voltage, I was thinking the same thing about holding it to 0v during the alignment. I wish I had looked closer at the chip driving the feedback signal to determine if I can simply tie the test point to ground since that part of the circuit will be unpowered. I will pop the board out again and prep it for the alignment. Try powering the VCO out side the chassis and determine the state of the feedback control and see how to hold it to 0V safely. My friends time is limited so I was going to figure this out before I head over there anyway.

I am having a bit of trouble attaching my photos, I will try and get them posted tomorrow.

Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 09, 2016, 12:21:27 pm
If you find the time you could complete my outstanding task and trace the route of the Varicap diode control line. you can then easily disconnect that line and isolate the Varicaps from the PLL drive. On my units it was obvious and easy, but on your units it takes a different path. It is much harder to me to trace the route without the module in front of me as continuity tests should quickly locate it. there will be a wire connection between the metal module chassis and the PLL board that sits on top of the module. It is direct and without buffering on the metal chassis side of the path. If you trace from the Varicap control point (IIRC the outer connections of the Varicaps on your module) to the PCB sitting 'North' of the VCO you will find that it terminates in the top tight of that PCB and then heads off to ??????

If you then use that point on the PCB for one continuity check probe, you should be able to find continuity of zero ohms between it and the connection on one of the PLL connectors and that is the PLL control line which needs to be isolated before tying the Varicap diodes control point to 0V

Some side comments......

1. The Varicap diode layout is different on your modules to mine. They are both reverses polarity and the control voltage is applied to the outer leads as opposed to the mid point in my module.
2. The mid point of the two Varicap diodes is biased by a voltage that must be present when setting up the VCO. In my module the bias was derived from the voltage supplied to the VCO power pin. Your module may apply a different bias voltage so the available swing of the VCO control may be less in your modules. This will mean more accurate setting of the VCO center frequency is advisable.
3. In my module there is a power resistor present that drops the voltage supplied to the VCO components (MMIC's) In your module this dropper resistor is not present, hence the lower VCO supply voltage at the power input pin.
4. Your module is an older version of the one for which I wrote the alignment notes. As such, please consider all guidance in that document suspect in relation to the alignment of your module. I suspect you have already discovered that !
5. The VCO center frequency remains the same on both the older module and the newer variant. You should aim for that voltage with the PLL control voltage at 0V as that will provide the most symetrical positive and negative frequency swing capability for the PLL.
6. Just in case it helps you ..... from memory, the PLL uses an LM324 to drive the Varicap control line.

Sorry I cannot help more at the moment. I am surrounded by work that I must get on with at the moment. My hobby work is effectively on hold  :(

Best Wishes and Good Luck

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 15, 2016, 07:06:14 am
Hi Fraser,

The alignment was a success :-+. Went much easier then I expected. I found the key is to make an small adjustment, cover the VCO area with a chunk of aluminum, measure, repeat. Sweeping the tuning "fork" gives you a rough idea where to target then simple from there. The Lo drive level at the test port was about -6dbm so I think the MMICs are in good shape.

A colleague and I traced out the PLL circuit and I have pictures I will post once I figure out why I can't get them to upload. As I identified earlier the DC voltage is 6.5V to the VCO MMICs and the same rail is also supplying a buffer MMIC, RF prescaler (MC12080), and a couple logic ICs (74AC74 x2, 74AC00) in the PLL circuit. A OPA27 is providing the drive to the varicaps.

I disconnected power from the passthrough to the VCO MMICs and drive only the VCO circuit with my bench supply. Since the rest of the PLL was not active, I simply tied the varicaps to ground via TP501. I will get some notes together and update the missing bits of your schematic in a few days time.

Thanks for the info,
Ty

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 15, 2016, 11:21:51 am
RadioAct,

It seems that you an I have the same unit.

Was there anything different that you did differently to get your units to work, that wasn't in Fraser's original alignment procedure?

If i read your post correctly you applied 6.5V to circuit while adjusting, is this correct? I can't remember exactly but I think that is right around what I was supplying when I was able to dial int eh Freq. But still no luck for me.

Thanks
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 16, 2016, 04:03:13 am
Yes I do think we have the same boards. Mine matches your pictures, notably the different arrangement of the varicaps and the different insulated pass-throughs.

The steps that I did were :
-I desoldered the little blue wire by U303 and attached my power supply directly to the PCB. I wanted to make sure that I was only powering the VCO as I didn't check out what else the 6.5V supply was powering.
-I soldered a ground wire to TP501 as that is the varicap control voltage line.
-I connected the test port to a spectrum analyzer and powered on the bench supply.
-I went looking for the Lo and I found that it was some 40Mhz lower. Uncovering the VCO had a major effect on the frequency as expected. I got a chunk of aluminum to cover it between adjustments.
-I tweaked the tuning "fork" a bit, measured, repeat until I was under 500kHz from 3840MHz
-Found out that tightening the adjustment screw caused the frequency to jump so I aimed a but under 3840 then when tightened it was nearly on target.
-Disconnect everything, reconnect the blue wire to the MMIC power supply near U303, pop on the cover and put in ~50 screws. Slide the RF deck back in the analyzer and reconnect.
-Run self test and now RF passes.  :-+

The only thing I can think of is that there was some component damaged when you initially tried 11.2V before finding out that this version of the board uses a 6.5V supply to the MMIC. Did you disconnect the VCO MMICs from the power rail as I did? I have confirmed that the 6.5V that powers the MMICs is common to the PLL circuit and powers the 74AC47 and 74AC00. Those guys are cmos and I don't think they would have liked the 11.2V supply for long.

Let me know if there is anything you would like me to test/measure/poke at at the RF board is currently apart on my bench. Next time it goes back together its for good.

Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 16, 2016, 01:03:08 pm
Thanks for the feedback.

I did not de-solder/isolate the circuit when I was applying the voltage, nor did I ground to the varicaps (I grounded to the chassis).

I also noticed the change when tightening down the screw, but did not use an aluminum to shield the circuit while measuring.

Unfortunately I do not have another Spec A to check the output with, only a Freq Counter so I may be at a bit of a disadvantage there.

I have my kids soccer this morning and some spring cleaning in the afternoon but I will try your "tweeks" later today and finally put this thing back together.

Thanks again.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 18, 2016, 06:04:00 am
If possible I suggest you give isolating the power to the VCO and cover it with some sort of shield between adjustments. I don't think there is anything wrong with using a frequency counter, if anything your frequency measurements will be more accurate than the way I did it with a Spec A. The spec A has the benefit of testing output level at the same time but it's not necessary. Tie the TP501 to ground.

Aim your adjustment for 3840MHz since the PLL will not be powered and the feedback voltage is tied to 0V. Absolute perfection is not necessary, I settled with 250kHz off of 3840MHz and when the PLL pulled it in it only took 0.3V of feedback voltage.


Now for some self promotion.
I have done up a short write up on the process I did on my website, best part is I posted all the photos.
http://www.tystech.com/repairs/aligning-the-advantest-r3132-spectrum-analyzer-2nd-rf-lo/ (http://www.tystech.com/repairs/aligning-the-advantest-r3132-spectrum-analyzer-2nd-rf-lo/)

Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 01:29:09 am
ok guys (and or girls).... I feel like I am actualy making some progress here with 1 last hurdle.

I just re-attempted the adjustment procedure with the "tweaks" posted by RadioAct.

During the adjustment I was only able to get it as close as 3810 (up to 3815 when I put the aluminum cover back on). I figured it was as close as I would get so I put it back together and fired the unit up.

(as a side note i still have the internal bracing removed so I am able to still monitor the "monitor port" while the unit RF Board is inside the chassis)

As soon as I turned it on I was getting 3480 on my Freq Counter (HOLLY CRAP!!!!)

So I ran the self test using Shift 0 and ALL TESTS PASS!!!! WHAAAAAT!!!!!

But then i tried to run the Self Cal (shift 7) and it still has the 807 Error "no cal signal detected"  |O

Anyone have any other suggestions? PLEASE!!!!!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 19, 2016, 01:51:39 am
I have to ask this so hope you do not take offence.... Did you connect a known good coax cable between the Cal output and SA input ?

Also, does your RF input N connector centre pin look to be in good condition. The pins leaves can break off due to abuse and cause a poor connection.

Sadly no immediate suggestions on other causes and I would want a Spectrum Analyser available to carry out checks on the signal oath. Your frequency counter may be of some use though.

I can say that 3815MHz is too low a frequency for the VCO centre point. I am surprised that the PLL is not struggling to achieve correct frequency lock at 3840MHz. It may be on the edge though so the VCO does need some attention at some point as it needs modification or repair to get it to tune around a centre of 3840MHz.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 02:13:19 am
Fraiser,

No offence taken...

In fact after I posted my post i sat for 15 min thinking about it and I had the same question (for myself).

So I went down stairs to try to swap around the cables. I only have 2 that I grabbed from work when i first started on this project. I assume they would work fine.

For a lack of better description one is long and black (maybe 5 ft or so) and one is short and grey (maybe 1 foot). They both have the same "BNC" style connectors.

Anyways, back to my results....

The "grey" 1 foot wire is the one that I always used to go form the cal out to the RF in because of its size. So i removed the longer one that was connected to my monitoring port and tried that.

Keep in mind that they both still failed due to "no signal" however one of them actually shows some sort of a signal (see pic).

I also confirmed that my output form the "cal out" is 30 MHz (30,000,008 Hz).

Do you think it is my cables?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 19, 2016, 02:21:18 am
Can you measure the level of the cal signal? It should be damn close to -20dbm. If it's not then there could be a cal signal issue or the drive level from the Lo to the mixer may be low.

-Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 02:25:22 am
Not form my house. I will need to take it into work to do that.

I was only able to confirm the Freq out was 30Mhz.

I do see that it puts the unit into -20db when the self cal starts. I assume you want me to hook that output to another Spec A?

Is that output a constant or does it only show up when you run the "self cal" program?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 19, 2016, 03:02:26 am
Sorry,
I meant put the cal out into the R3231 and see how it measures, I believe it is always on. Set the center to 30MHz and span to 20Mhz'ish. You should see a tone. Peak search it and you will get a marker and an amplitude. Without cal it can't be trusted, but should be in the ball park of -20dbm. Of course a third party spec A or power meter would be great but we will work with what you have.

-Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 03:22:22 am
This is what I get (when i use the black cable... i get nothing when i use the grey one)
Title: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 19, 2016, 04:04:49 am
Ok I wrote up about four questions before I hit post. I thought about each then rewrote this lol.

I make the assumption that your black cable is serviceable.
During cal the first thing it does is a user test, look for the cal signal at about the right level and frequency, make sure the user actually plugged in the cal signal :) It will look for a tone at exactly 30MHz and within a power range about -20dBm. I don't know the exact ranges but -74 is not close enough.

-First I would like to confirm the measured frequency. Does it dance around at all?
-Can you run the frequency counter on the unit and measure the frequency of the tone. I want to see it come back as exactly 30.000000MHz. Since it generates its own cal signal from the same low frequency reference there should not be any variance if all the PLLs are locked and operating correctly.
-Is the RF still passing self test? I would bet $$$$ that the self test does not do much more than check PLL lock detect signals and some other simple checks, that is why it happens so fast. If you have all the lock detects and pass self test then I would say you do have a 3840MHz Lo.


Assuming that you do indeed have a stable exactly 30MHz cal signal then I am inclined to suspect the MMICs. My thoughts here need confirmation from an expert as I am only familiar in passing with RF. Here goes:

There are three MMICs in the 2nd Lo, one that drives the oscillator, one that amplifies a take off from the VCO and drives out to the mixer (also drives the test port), and the third that drives the frequency divider part of the PLL from the output of the 2nd MMIC. If for example the middle guy is damaged, the Lo drive to the mixer would be low which would show up as a low or missing amplitude on the trace, however the 3rd MMIC could still drag up the signal enough from the noise for the divider circuit to do its job and bang you get a functioning Lo with insufficient output drive into the mixer.

I do recall reading that Fraser had replaced the MMICs in one of the units he worked on, perhaps this may be needed.

-Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 11:24:19 am
To answer your questions...

1/2. When I hook the cal out to my Freq Counter (with the black cable) I get 30,000,008. I thought I posted a pic earlier of that reading... Not exactly 30, but I would think that is acceptable, no?

3. Yes the RF Self Test is still passing. Before last night that would always fail.

I will wait to see if anyone else, especially Fraser has any input.

I will also try to grab another set of cables from work today as i am still a bit suspicious of the huge difference in readings using the 2 that I have.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 19, 2016, 11:48:35 am
Had a thought overnight. You must be using an N to BNC adapter on you SA if using BNC patch leads. You need to check that adapter for good connection. I have had issues with even simple straight through Connector adapters not making good contact on the centre pin.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 11:51:27 am
Fraser,

I actually have 2 different N to BNC adapters, I get the same results from both.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: CJay on April 19, 2016, 12:00:15 pm
Seeing as your marker suggests -74dBm (even uncalibrated I'd still expect somewhere near, seeing ~50dBm difference is too much)  I'd suggest it's a dodgy cable or extremely low output from the CAL signal, in lieu of another SA perhaps verifying it with something like an AD8307 based power meter might be an idea?

30MHz isn't a particularly high frequency and if you can meter out the cable from end to end as well as verifying no shorts I'd probably accept it is OK, especially as I think you have the same results with both cables.

oops, my bad, you get no signal with the grey one. Possibly two dodgy cables then, I'd be tempted to try and find another.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 12:03:30 pm
CJay,

I currently don't get the same results form both cables. I am suspicious that one is not working at all.

I will check to see if there is a power meter here at work that I can grab.

Are there any other suggestions for test devices that might help make this easier to troubleshoot?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: CJay on April 19, 2016, 12:19:05 pm
Quote from: jc81382 on April 19, 2016, 12:03:30 pm
CJay,

I currently don't get the same results form both cables. I am suspicious that one is not working at all.

I will check to see if there is a power meter here at work that I can grab.

Are there any other suggestions for test devices that might help make this easier to troubleshoot?

Yeah, I realised after I'd posted that one cable was definitely faulty and edited but I guess you saw before I saved the changes.

I'd definitely try to find another cable and if possible ditch the BNC to N adapters if possible.

-20dBm is pretty low, in the region of 60mV P-P so you're going to struggle to measure it with something like a simple diode probe and you'll need to make sure that any power meter you borrow is sensitive enough to measure that sort of signal level too.

A 'scope would be useful if you can borrow one. 

The Analog Devices AD8307 (or similar) chip could be used to 'knock up' a simple power meter that'd give you a reasonably close measurement.

If you search for Wes Hayward AD8307 you'll get a ton of hits and schematics.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: RadioAct on April 19, 2016, 03:08:06 pm
For what its worth, here is a half assed measurement of the Lo from the test port on my sepc A. Hopefully your issue is just a bad cable/connector.
(http://www.tystech.com/wp-content/gallery/R3132/2016-04-13-17.31.40.jpg)

-Ty
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 19, 2016, 06:52:10 pm
So i tried a 3rd cable and i get the same results as i currently get from the black cable.

I'm trying to see if i can take a power meter home, and if you i will get all the screws put back into the unit and take it to work tomorrow and hook it up here.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 20, 2016, 11:48:36 am
quick update...

I have the unit with me at work and just hooked it up to a power meter and I am getting exactly -20 db out of the "cal out" and confirmed that it is putting out a freq of 30 Mhz.

However when feeding directly into the RF in it is reading -70 db, I assume this is the issue with it not seeing the cal signal.

It is with one of out RF Technicians now and h said he also checked the attenuation and that seems to be working fine.

Also, we noticed that when you go into the Self Cal menu there is a options for input reference (or something like that) do you think that might be something that needs to be set or changed?

Any ideas?


Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 20, 2016, 01:41:51 pm
As another quick follow up...

When we source from an external unit a 30 Mhz output we need to up the amplitude to ~ -3 db to get the Spec A to register -20 (as it should be seeing from the Cal Out).

Now, I may be wrong but I assume that when the unit performs the "Self Cal" that it will make any adjustments/offsets to that 30 Mhz @-20db signal. So I am not that surprised that things are reading off. After all this unit was sitting for quite some time, and had a dead CPU battery so any correction that may have been programmed into it have  been lost.

My real question here is when you attempt the "Self Cal" there is a mechanical clicking noise that I assume preparing the unit receive the expected Cal Out signal.

Does anyone think there might be ab issues with some sort of relay that might not be functioning properly and causing that to not happen?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 02:49:01 pm
If you feed a 50 Ohm RF signal source into a 50 input Spe trump Analyser and the source signal is so heavily loaded that it is taken below its calibrated output, you have a lo impedance fault on the front end of the Spectrum Analyser.

Sadly I do not recall the exact topology of the RF input and I would need to review my photographs of that section. Your fault would suggest that an overload protection device has gone low impedance and remained so. It is not unusual to have protection limiters in sensitive RF inputs in order to protect the front end amplifiers and mixers from overload.

This needs to be investigated as it is very likely the cause of your no calibration signal situation.

In the front end of a spectrum Analyser you would expect to find the following order of components......

RF input connector
Series DC blocking capacitor
Sometimes a protection limiter
RF Attenuator, either mechanical or pin diode type.
Sometimes an RF buffer amplifier
1st Mixer to down convert input signal to 1st IF frequency.
1 st IF filter to remove unwanted mixing products and 1st LO breakthrough.
RF amplifier
The signal then passes to any further filtering and the second mixer to create the 2nd IF, then filtered, then amplified and so on.

Let me take a look at the photos I have of your modules front end and I will advise further.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 20, 2016, 02:59:18 pm
Fraser,

I believe I uploaded pictures of this area back when you were asking for them.

If you need something more hi-res please let me know.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 03:04:52 pm
OK,

A quick look at the block diagram I produced shows the following input configuration......

RF input connector
I assume a DC blocking capacitor follows but not on my diagram.
0 to 50dB attenuator block
Low pass RF filter
RF relay - DPDT to insert or bypass an ERA-3 MMIC RF amplifier
Low pass RF filter
1st Mixer
IF filter
82J MMIC RF Amplifier 1
82J MMIC RF Amplifier 2
IF filter

If the input to the spectrum analyser is heavily loading an RF source you could have a low impedance fault in the RF attenuator block, MMIC amplifier (if in circuit for calibration) or the 1st Mixer if MMIC is not in circuit.

I will confirm the above above by looking at the photos of the board.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 03:44:40 pm
Here are some pictures of the older module front end. I believe this is what your unit looks like ?

The later version has just a semi rigid coax between the input connector and a self contained attenuator module positioned on the other side of the chassis.

The older design is quite a muddle of components so I will need to study it some and come back to you on its configuration.

Chores to do now so it will have to be later.

please find out how the tech went about testing the attenuator block.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: CJay on April 20, 2016, 03:54:45 pm
Quote from: Fraser on April 20, 2016, 02:49:01 pm
If you feed a 50 Ohm RF signal source into a 50 input Spe trump Analyser and the source signal is so heavily loaded that it is taken below its calibrated output, you have a lo impedance fault on the front end of the Spectrum Analyser.

Fraser

Hypothesis:

We know the SA can display the signal applied but the level indicated is drastically lower than it should be (-74dBm instead of a verified -20dBm) then we can assume it's either loading the signal down or it's somehow attenuating the signal, so how about using a T piece to monitor the signal level on the power meter when it's fed into the SA input?

Even with the (extra) impedance mismatch the power meter should, if the SA front end is still a good 50 Ohm match, indicate a relatively close power level (I *think* less than 5dB different) which would indicate the ~50dB difference is caused by a gain/buffer stage not working.

Of course, if the SA front end is faulty then the cal signal power indicated on the power meter will drop drastically.


Might help isolate the problem a little further perhaps?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 05:04:36 pm
Quick and dirty sketch of front end circuit in older R3132.

No overload protection present before attenuators.

Small attenuator pad and DC block capacitors just behind input socket.

What looks to be overload detector present

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 05:09:04 pm
CJay,

Thanks for pointing this out. I had, possibly incorrectly, assumed that he had injected a known level of signal into the SA and the signal had been loaded down. if it is just the reading on the faulty SA that is low, that is a whole different scenario

Apologies if I misread the symptoms. Too much going on in my life today !

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 20, 2016, 05:09:41 pm
is that a component that can be easily purchased and possibly replaced?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 20, 2016, 05:14:21 pm
Just to be clear I supplied a signal from a separate, calibrated instrument. I think it is a HP Sig Gen or something (I can confirm if you want)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 05:24:25 pm
You mean the overload detector ?

That is made up of R203, R202, C200, L? and D200.

Sadly this is unlikely to cause your symptoms even if faulty.

I misread your latest posts.

From what I can now gather. You feed a signal of known amplitude into the SA and the SA shows a much lower reading than expected. Your tech has tested the attenuator and it is working OK.

Sadly the causes of a low reading or poor sensitivity in an SA are many.

You could have a low LO injection level at the first mixer.
The first mixer may be damaged (quite common if the SA is overloaded)
The I.F. chain may have a failed gain stage (MMIC).

The way to find such a fault is to trace the signal level through the analysers signal path. The point at which the expected level is not present tends to indicate a problem in the preceding stage. For example, a low output from the 1st mixer could be due to a low LO injection level or a failed diode in the mixer pair. A drop in level or lack of gain after an MMIC amplifier stage would suggest failure of the MMIC or its power supply. etc etc. For speed, the half split method is often applied to multi stage superheterodyne systems like this but damage is most likely at the front end due to abuse so you can inject a signal at the input and just follow its level through the carious stages.  Sadly this is easy to say, but harder to accomplish with the module design in the R3132. Sorry this is not likely to be a simple repair task with the module mounted in the chassis.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: jc81382 on April 20, 2016, 05:32:19 pm
Hmmm... I wonder if i should just look for a replacement module on e-bay or something.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 05:37:01 pm
Three areas of interest in the front end circuits

1. PCB interconnections - bad joints have been found in the past. These effectively become low value series capacitors !
2. Gain stage switched in and out by a relay. The gain is provided by the 4 legged MMIC
3. 1st Mixer. It looks like a tiny pill and is mounted perpendicular to the PCB. Three legs and contains two diodes. Very fragile !
The grey blocks glued around the mixer should not be removed as they are required to suppress parasitics.

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Fraser on April 20, 2016, 05:41:01 pm
Sadly the R3132 modules are not a common item to find as they are usually still in the chassis of faulty units that are sold on ebay. It is also the module that tends to give the problems !

Fraser
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: CJay on April 22, 2016, 01:06:42 pm
Quote from: Fraser on April 20, 2016, 05:09:04 pm
CJay,

Thanks for pointing this out. I had, possibly incorrectly, assumed that he had injected a known level of signal into the SA and the signal had been loaded down. if it is just the reading on the faulty SA that is low, that is a whole different scenario

Apologies if I misread the symptoms. Too much going on in my life today !

Fraser

Ah, and my wording is ambiguous, I meant I was offering a hypothesis, from the information available I can't work out if the signal is being loaded down, if it's being attenuated somewhere, a measurement error or even a combination of the three.

Still, as envious as I am of anyone who can lay hands on this sort of equipment for such low prices, I'm enjoying the thought exercise and learning.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Cech on September 14, 2016, 10:05:31 pm
Quote from: krivx on October 19, 2015, 01:42:00 pm
Quote from: Fraser on July 16, 2015, 11:17:45 am
Standard operating procedure for replacing a Lithium cell whilst maintaining power to the SRAM...

1. Buy a 2 cell AA or AAA battery holder with flying lead output for connection to a PCB.
2. Fit 2 cells in the holder  ;D
3. Solder the flying leads to the supply rails that the Lithium battery maintains (observing polarity)
4. Cut the lithium battery off of the PCB
5. Desolder the lithium battery pins
6. Insert the new Lithium battery and solder its pins.
7. Desolder the battery holder flying leads.
8. Job done  :)

Note this is all done with the power to the equipment OFF !

For the very nervous amongst you, you can usually insert a 1K resistor in series with the battery holder flying leads, though this is not normally needed in the real world.

This approach came from an OEM service manual and is not some 'hack' method  :-+

Aurora

Doesn't this require a floating soldering iron? I don't think touching an ESD-safe tip to a powered rail is a great idea...


!! I want specify better these procedure: if you change the lithium battery and you have installed the option TG (Traking Generator),
you will lost all the additional firmware for the TG and the TG will stop to work and a error message it will appear on the display.
If someone have this problem, I have all the firmware needed to re-load again with the floppy disc, and all the procedure and password needed to load the TG firmware again. !!

I hope this can solve the problems "if" the battery it's sudden dead, otherwise if you not want losing the firmware for the TG, connect the new one battery in parallel to the old one, and after you will remove the old one.
I hope this can help someone with trouble...

Ciao
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on September 14, 2016, 10:31:20 pm
Can you post this somewhere?
I suggest this website: http://www.ko4bb.com/getsimple/index.php?id=manuals (http://www.ko4bb.com/getsimple/index.php?id=manuals)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on September 17, 2016, 01:01:23 am
Quote from: Cech on September 14, 2016, 10:05:31 pm
Quote from: krivx on October 19, 2015, 01:42:00 pm
Quote from: Fraser on July 16, 2015, 11:17:45 am
Standard operating procedure for replacing a Lithium cell whilst maintaining power to the SRAM...

1. Buy a 2 cell AA or AAA battery holder with flying lead output for connection to a PCB.
2. Fit 2 cells in the holder  ;D
3. Solder the flying leads to the supply rails that the Lithium battery maintains (observing polarity)
4. Cut the lithium battery off of the PCB
5. Desolder the lithium battery pins
6. Insert the new Lithium battery and solder its pins.
7. Desolder the battery holder flying leads.
8. Job done  :)

Note this is all done with the power to the equipment OFF !

For the very nervous amongst you, you can usually insert a 1K resistor in series with the battery holder flying leads, though this is not normally needed in the real world.

This approach came from an OEM service manual and is not some 'hack' method  :-+

Aurora

Doesn't this require a floating soldering iron? I don't think touching an ESD-safe tip to a powered rail is a great idea...


!! I want specify better these procedure: if you change the lithium battery and you have installed the option TG (Traking Generator),
you will lost all the additional firmware for the TG and the TG will stop to work and a error message it will appear on the display.
If someone have this problem, I have all the firmware needed to re-load again with the floppy disc, and all the procedure and password needed to load the TG firmware again. !!

I hope this can solve the problems "if" the battery it's sudden dead, otherwise if you not want losing the firmware for the TG, connect the new one battery in parallel to the old one, and after you will remove the old one.
I hope this can help someone with trouble...

Ciao

Great news, how do I get a copy of the code to reload the TG?  I've been needing to change my battery but was afraid of screwing up and losing the TG.

Thanks!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Cech on September 21, 2016, 04:37:59 pm
Quote from: cncjerry on September 17, 2016, 01:01:23 am
Quote from: Cech on September 14, 2016, 10:05:31 pm
Quote from: krivx on October 19, 2015, 01:42:00 pm
Quote from: Fraser on July 16, 2015, 11:17:45 am
Standard operating procedure for replacing a Lithium cell whilst maintaining power to the SRAM...

1. Buy a 2 cell AA or AAA battery holder with flying lead output for connection to a PCB.
2. Fit 2 cells in the holder  ;D
3. Solder the flying leads to the supply rails that the Lithium battery maintains (observing polarity)
4. Cut the lithium battery off of the PCB
5. Desolder the lithium battery pins
6. Insert the new Lithium battery and solder its pins.
7. Desolder the battery holder flying leads.
8. Job done  :)

Note this is all done with the power to the equipment OFF !

For the very nervous amongst you, you can usually insert a 1K resistor in series with the battery holder flying leads, though this is not normally needed in the real world.

This approach came from an OEM service manual and is not some 'hack' method  :-+

Aurora

Doesn't this require a floating soldering iron? I don't think touching an ESD-safe tip to a powered rail is a great idea...


!! I want specify better these procedure: if you change the lithium battery and you have installed the option TG (Traking Generator),
you will lost all the additional firmware for the TG and the TG will stop to work and a error message it will appear on the display.
If someone have this problem, I have all the firmware needed to re-load again with the floppy disc, and all the procedure and password needed to load the TG firmware again. !!

I hope this can solve the problems "if" the battery it's sudden dead, otherwise if you not want losing the firmware for the TG, connect the new one battery in parallel to the old one, and after you will remove the old one.
I hope this can help someone with trouble...

Ciao

Great news, how do I get a copy of the code to reload the TG?  I've been needing to change my battery but was afraid of screwing up and losing the TG.

Thanks!

If you change the battery with some precautions, ther are not problems (like two battery in parallell and after you will remove the old one).
In case all will it went wrong... I can email to you all the complete procedure, file to save in the floppy disc and the password.

Ciao
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: utkuzu on November 17, 2016, 01:23:33 pm
Quote from: Cech on September 21, 2016, 04:37:59 pm
Quote from: cncjerry on September 17, 2016, 01:01:23 am
Quote from: Cech on September 14, 2016, 10:05:31 pm
Quote from: krivx on October 19, 2015, 01:42:00 pm
Quote from: Fraser on July 16, 2015, 11:17:45 am
Standard operating procedure for replacing a Lithium cell whilst maintaining power to the SRAM...

1. Buy a 2 cell AA or AAA battery holder with flying lead output for connection to a PCB.
2. Fit 2 cells in the holder  ;D
3. Solder the flying leads to the supply rails that the Lithium battery maintains (observing polarity)
4. Cut the lithium battery off of the PCB
5. Desolder the lithium battery pins
6. Insert the new Lithium battery and solder its pins.
7. Desolder the battery holder flying leads.
8. Job done  :)

Note this is all done with the power to the equipment OFF !

For the very nervous amongst you, you can usually insert a 1K resistor in series with the battery holder flying leads, though this is not normally needed in the real world.

This approach came from an OEM service manual and is not some 'hack' method  :-+

Aurora

Doesn't this require a floating soldering iron? I don't think touching an ESD-safe tip to a powered rail is a great idea...


!! I want specify better these procedure: if you change the lithium battery and you have installed the option TG (Traking Generator),
you will lost all the additional firmware for the TG and the TG will stop to work and a error message it will appear on the display.
If someone have this problem, I have all the firmware needed to re-load again with the floppy disc, and all the procedure and password needed to load the TG firmware again. !!

I hope this can solve the problems "if" the battery it's sudden dead, otherwise if you not want losing the firmware for the TG, connect the new one battery in parallel to the old one, and after you will remove the old one.
I hope this can help someone with trouble...

Ciao

Great news, how do I get a copy of the code to reload the TG?  I've been needing to change my battery but was afraid of screwing up and losing the TG.

Thanks!

If you change the battery with some precautions, ther are not problems (like two battery in parallell and after you will remove the old one).
In case all will it went wrong... I can email to you all the complete procedure, file to save in the floppy disc and the password.

Ciao
I have the same problem. But my battery was death completely so tg and other add programs was death too. Could you send me e-mail your programs and password, please?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: utkuzu on November 28, 2016, 07:26:00 pm
Quote from: utkuzu on November 17, 2016, 01:23:33 pm
Quote from: Cech on September 21, 2016, 04:37:59 pm
Quote from: cncjerry on September 17, 2016, 01:01:23 am
Quote from: Cech on September 14, 2016, 10:05:31 pm
Quote from: krivx on October 19, 2015, 01:42:00 pm
Quote from: Fraser on July 16, 2015, 11:17:45 am
Standard operating procedure for replacing a Lithium cell whilst maintaining power to the SRAM...

1. Buy a 2 cell AA or AAA battery holder with flying lead output for connection to a PCB.
2. Fit 2 cells in the holder  ;D
3. Solder the flying leads to the supply rails that the Lithium battery maintains (observing polarity)
4. Cut the lithium battery off of the PCB
5. Desolder the lithium battery pins
6. Insert the new Lithium battery and solder its pins.
7. Desolder the battery holder flying leads.
8. Job done  :)

Note this is all done with the power to the equipment OFF !

For the very nervous amongst you, you can usually insert a 1K resistor in series with the battery holder flying leads, though this is not normally needed in the real world.

This approach came from an OEM service manual and is not some 'hack' method  :-+

Aurora

Doesn't this require a floating soldering iron? I don't think touching an ESD-safe tip to a powered rail is a great idea...


!! I want specify better these procedure: if you change the lithium battery and you have installed the option TG (Traking Generator),
you will lost all the additional firmware for the TG and the TG will stop to work and a error message it will appear on the display.
If someone have this problem, I have all the firmware needed to re-load again with the floppy disc, and all the procedure and password needed to load the TG firmware again. !!

I hope this can solve the problems "if" the battery it's sudden dead, otherwise if you not want losing the firmware for the TG, connect the new one battery in parallel to the old one, and after you will remove the old one.
I hope this can help someone with trouble...

Ciao

Great news, how do I get a copy of the code to reload the TG?  I've been needing to change my battery but was afraid of screwing up and losing the TG.

Thanks!

If you change the battery with some precautions, ther are not problems (like two battery in parallell and after you will remove the old one).
In case all will it went wrong... I can email to you all the complete procedure, file to save in the floppy disc and the password.

Ciao
I have the same problem. But my battery was death completely so tg and other add programs was death too. Could you send me e-mail your programs and password, please?

Thanks for your helps Cech. I will share your files and your passwords and documents. Thanks a lot.

http://www.mediafire.com/file/n3uu1gaklbytkxh/Advantest+3131+Firmware+Tracking.zip (http://www.mediafire.com/file/n3uu1gaklbytkxh/Advantest+3131+Firmware+Tracking.zip)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaucySoliton on November 28, 2016, 11:37:16 pm
If your firmware is new enough, you don't need the floppy. Just enter the password and enable the option.  My TG seems to be working fine now.

The file appears to be a general purpose firmware upgrade. I would guess rev B01 by looking at the strings.  My unit had rev B02 already so I avoided a possible downgrade.


Thank you all for your help!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: utkuzu on November 29, 2016, 10:27:21 am
I lost my factory default. Could you write me some values? Shift+5 , pass: 882323 , I RF, YTO Tune, Max1stLO and Min1stLO  hexadecimal values. Thanks your helps.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on November 29, 2016, 10:38:57 am
AFAIK you should be able to do a self calibration to get all these values right.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: utkuzu on November 29, 2016, 03:21:18 pm
Quote from: nctnico on November 29, 2016, 10:38:57 am
AFAIK you should be able to do a self calibration to get all these values right.
I cannot do self calibration because factory defaults have changed. So I need these values.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on November 29, 2016, 03:31:50 pm
I no longer have my R3131 but after I changed the battery on mine all I had to do was a self calibration and everything was fine. There is also a button near the rear on the motherboard which seems to load some defaults. I needed to press that one during startup to get my R3131 running properly after the battery swap.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: utkuzu on November 29, 2016, 03:45:01 pm
Quote from: nctnico on November 29, 2016, 03:31:50 pm
I no longer have my R3131 but after I changed the battery on mine all I had to do was a self calibration and everything was fine. There is also a button near the rear on the motherboard which seems to load some defaults. I needed to press that one during startup to get my R3131 running properly after the battery swap.
I changed RF Tunes on engineer mode because tracking generator is not working right. After that I couldn't do calibration at all.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on November 29, 2016, 03:55:17 pm
Try pressing the button on the CPU board first. I'm not sure what it does or when you need to press it. I pressed it during startup and I kept it pressed for several seconds while the R3131 is running. Be creative here because all I know is that it fixed my problems.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaucySoliton on November 30, 2016, 05:32:30 pm
Quote from: utkuzu on November 29, 2016, 10:27:21 am
I lost my factory default. Could you write me some values? Shift+5 , pass: 882323 , I RF, YTO Tune, Max1stLO and Min1stLO  hexadecimal values. Thanks your helps.

Max1stLO 0x0DA6
Min1stLO  0x0120
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on December 02, 2016, 01:29:19 pm
I'm now too an owner of this type of Spectrum analyzer and naturally it didn't came home to me the way it was described on ebay: "Fully Functional".

The RTC-Battery is completely flat (I'm getting 0.002V out of circuit) and the Analyzer starts with a "RTC No Data" error. Everything else works fine.
Until I run the Self Test or the Calibration.

Calibration throws a "Error 100 IF Step Amp"-Message. And the Self Test claims the CPU is faulty. Which I cannot believe, as everything else is working although with a slightly lower measured amplitude than expected (about -2dB).

I'm off to get a new Battery now, but in the meantime I would like to ask what else could be wrong with the CPU-Board?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on December 02, 2016, 09:12:24 pm
As I suspected, the new battery solved the problem that the Self Test detected a faulty CPU.
For a short period of time, Error 100 "IF STEP AMP: Calibration Failure" was also gone. It took about 20 minutes of warmup for this error to reappear again.

What I noticed when checking the calibration feature, the -10dBm Cal-Signal is measured as 5dB too low with the Cal Correction turned Off. There also is at least some action happening when the IF Step Amp is being calibrated. So I guess that there's something wrong with the adjustments on the IF/LOG-Board.
Also when cold, and IF Step Amp is successful, the Cal-Signal is displayed as 1dB too high. Once the device is warmed up, it is about 0.3dB too high (at the edge of the specified uncertainty).

I hope that my device has "just" drifted too much and just requires some fiddling with the Pots. Do you know which Pots to turn, or is there any schematic, reverse engineered or from Advantest, that could give a hint on where to put the screwdriver? There is a video linked on page 2 of this thread that deals with this topic, but it is in french and I don't know french.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on December 02, 2016, 10:36:17 pm
This seems very similar to your problem and the solution appears to be replacing 2 DACs:
https://groups.yahoo.com/neo/groups/advantestinstrument/conversations/topics/139 (https://groups.yahoo.com/neo/groups/advantestinstrument/conversations/topics/139)

Also discussed on the first page of this thread: https://www.eevblog.com/forum/testgear/advantest-r3131a-spectrum-analyzer-9khz-3ghz/msg245395/#msg245395 (https://www.eevblog.com/forum/testgear/advantest-r3131a-spectrum-analyzer-9khz-3ghz/msg245395/#msg245395)

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on December 02, 2016, 11:22:34 pm
Thx for the links. I have downloaded the zip-archive provided in the Yahoo Group and had a quick look through the folders.

Pretty interesting construction with varactors instead of trim-capacitors. I was thinking about using a similar construction in my own design, but opted for trim-caps in the end.


Btw. It currently appears as if my device is working now. Maybe it needed to cook out some moisture or just needed a few bangs after being ferried from estonia to germany via Air mail.
Also for a time it didn't want to update the date and time. Now it does...
Is there a newer Firmware available? The Revision Info says I have Revision C00 with no Options activated (there are none installed according to the sticker on the back).
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on December 03, 2016, 03:09:33 am
Okay, I have been playing around with the Analyzer and found something odd or rather worrying:
At +/- ca. 7MHz from the 30MHz Cal-Signal I see signals with a power of about -50dB. I haven't noticed those before and when I look at the manual, they are there but about 20dB lower.
I've also seen similar signals when I connect my PM5190.

My guess is that one of the Mixers is being overdriven, or has problems once fully warmed up. Power Measurements are still accurate though: The Signal from the PM5190 is pretty much the same that the scopes show and the Cal-Signal is sitting at -10dBm (ca. -12.5dBm with the Cal Correction turned off).


Btw. if anyone is still searching for a way to enable "forgotten" Options: When playing around with the instrument, I found out that SHIFT + 9 opens the Options-Menu, which is password protected (882323 worked for me). Once in there, the Tracking Generator and the "Type A"-Option (whatever that is) can be activated by the push of a button.
What does "Type A" in this context mean though? R3131"A", or is it the model with the second RF-Input?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: diarcy on March 12, 2017, 01:20:22 pm
For those that have lost their "Options" on the R3131, I found a procedure on another Advantest Group that has restored my Tracking Generator.

Apparently, the procedure is also good for other options that may have been lost.

Here's the recovery procedure after losing your options due to a battery change:

Use the following sequence to restore the TG option:
<Shift> <9>
Password: 882323 <Hz>
"TG Option >"
"Load"
“Exit”

You should then be able to again use the tracking generator.

If you have other options installed in your R3131, I believe you will need to "Load" each one. If you have an R3131A, I read that there's an option to tell the CPU that you have the "A-type" version which restores the 10kHz span option. The password above appears to be the "default" password for the instrument.

Hope this helps others... I was without my Tracking Generator for over a year!

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on March 12, 2017, 05:12:12 pm
You are my hero! I've been worried about changing my battery and losing my TG. 

How can I ever thank you!?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: flolic on March 21, 2017, 05:11:29 pm
I can confirm that above procedure for restoring options works  :)
My unit is R3131 with secondary RF input, which now works again. I also enabled "A" option, for R3131A and now minimum span is 10kHz.

One question. There is option for enabling RBW of 300Hz but on my unit it doesn't work correctly. Is there difference between 3131 and 3131A regarding RBW?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on March 22, 2017, 03:32:02 am
I have the RBW of 300hz on my R3131a and it works fine.  Maybe there is a real filter in the real A versions that is missing on yours?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: flolic on March 22, 2017, 11:44:36 am
I don't know.
In some user manuals there is 300Hz to 1MHz, and in some 1kHz to 1MHz  RBW, regardless of SA variant...
I can enable that option on my instrument, but displayed RBW looks more like 3kHz. I don't know if my unit just doesn't have that filter, or something is wrong with it.
Self test and calibration passes just fine.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: flolic on March 25, 2017, 11:19:48 am
So, I've took the cover of from my IF-LOG board and found what's wrong with 300Hz RBW option, -some parts (resistors, capacitors and diodes) are missing  :(
Those should be very easy to install, if I only know the capacitor values... At least I can read resistor values from hi res pictures from the first post.
What's interesting is that PCB part number is the same for 3131 and 3131A analyzers (BLL-023464), only my board is obviously from the first batch, it is 1997 Copyright.

(https://www.dropbox.com/s/ppu3sf9mja5bgok/R3131_IF_LOG_web.jpg?raw=1)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nair.sujith.v on April 07, 2017, 04:26:56 am
Firstly, a big thank you to marshallh & Marcel for solving the Total Gain failure on R3131A during self test. I now have the same problem.

So here is my question before I order parts and make the replacement:

1. Did replacing the 4072 opamps solve the problem for good or did it revert back in time?
2. Where is the MAX4106 located on the board? Is it underneath one of the shielding cans on the RF board? If so, which one?

Is solution 1 or 2 above a better long term fix?

Thanks,
Sujith
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nair.sujith.v on April 19, 2017, 03:45:38 am
Quote from: Marcel on October 20, 2015, 02:25:15 pm
https://www.youtube.com/watch?v=ZQ_S4Br1ftg (https://www.youtube.com/watch?v=ZQ_S4Br1ftg)
https://www.youtube.com/watch?v=nZ2W3clPFdA (https://www.youtube.com/watch?v=nZ2W3clPFdA)

Regards,

Marcel

Thank you very much. This solved my Total Gain failure after warm-up    :)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on September 19, 2017, 02:49:55 pm
I have an R3131A with TG, after about 10 minutes the TG signal drops out.
I have pulled all the cards out of the chassis, and the power supply.
 Nothing appears burnt.
 Nothing smells burnt.
 Pass power up self tests.
 Passed self Calibration.
 
I put the power supply back in. I noticed voltages silk screened on the Buss PCB, on the side where the display was connected, behind the display.

                 J10   +5.2V   +12.6V    and    J9  -12.6V    +24V

I measure           +5.24V  +7.41                   -12.66V  +24.27

There is an unmarked pin on J9 that is 2.29V


The supply is marked AT120-5224/M NEMIC-LAMBDA
The supply looks like several switcher supplies in one.
I'm thinking it's a bad regulator.

I like to know if anyone has and can share a schematic for the power supply?
If anyone has a fixed a similar issue, and has advice?
 
Edit:
     I found a refurbished for $750 USD in Europe.
 
     I disconnected the CPU style fan and I have 12.6V.
     More testing needed. I hope it's just the fan.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on September 19, 2017, 07:24:54 pm
I am thinking the Tracking Generator shutting down is unrelated to the 12V.

I have 12.64V at the Red wire to the LCD back-light. Still with the fan disconnected.
I also have a small fan blowing in to the case for cooling.
The T.G. went from -40dbm to -80dbm.
I ran the self test Shift 0 All tests pass.

Re-ran Self test, after I press the soft key to exit, the self test, the T.G. returned for a few minutes then
slowly dropped in amplitude.   
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on September 19, 2017, 08:25:35 pm
Did you check the 12V power rail with a scope? It wouldn't surprise me if there is a huge amount of ripple on it due to a leaky capacitor in the PSU or another problem in the power supply.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on September 20, 2017, 11:50:12 am
I did not, now I have, it is clean less then 65mV ripple same on the 5V, using the frame as ground.
Measured with a Tektronix TDS220, using the cursor lines peak to peak.

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on October 01, 2017, 06:31:45 pm
Summary of the problem-solving shown in the french videos that fixes the "Total Gain"-Error:

The problem lies in the variable gain amplifier INSIDE the RF-Section - The big, heavy block on the bottom module.

The OpAmp in question is U105 and the resistor that needs to be changed is R120.
As suggested in the Video, I changed the value from 390 to 470 and the error was gone.
Unfortunately, the video doesn't really show (I don't speak french and used the youtube-subtitles so I cannot say if he mentioned the exact location) where the OpAmp is located and how to access it.

You get access to it by removing the big bottom cover of the RF-Block. The RF-Gasket holds it in place even after the screws have been removed and requires a bit of force to come off. I used by fingernail as a wedge and lifted it in one corner by about a millimeter. Then the whole cover suddenly popped loose. So better have your other hand ready to catch it and prevent it from jumping up and falling back down on the PCB. Luckily mine took no damage.

The resistor is in the rear area with the green soldermask and can easily be replaced with a 0805 resistor.

A quick check of the analyzer afterwards revealed no immediate change in amplitude of the cal-signal - it was still about -9,7dBm, but to be sure, the analyzer should be properly calibrated after this procedure.

All in all, a rather easy repair, even though it requires disturbing the sacred RF-Block. But a nice prayer to the omnissiah to please the machine spirit and nothing should go wrong. :D
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Marcel G on January 26, 2018, 10:19:34 pm
After a lot of reading on the internet and informing, I managed to replace a damaged 1st mixer of a Advantest R3131.
The original mixer (DMJ 4317-1) is no longer available but has found an excellent alternative by using an HSMS-2822.

Below you see two photos, one with the damaged mixer and a picture with the alternative mixer. Both photos were taken without any RF input. The differences are clearly perceptible.

Probably these diodes can also be used in other older Advantest Spectrum Analyzers, take advantage of them.

In any case, there is exactly the same mixer in the U4342 that I also have.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on January 27, 2018, 06:11:48 am
Thanks, keep the hacks and fixes coming.  I think this analyzer is underrated by the community.  I have a 3131a with TG and it is accurate and easy to use.  Paid $750 for it 5yrs ago, the guy wanted a heck of a lot more but i kept after him.  No regrets.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on January 27, 2018, 03:06:51 pm
AFAIK there are also issues with the analog switches.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on January 28, 2018, 06:36:31 pm
whomever figured out the whole shift-9 password thing should get our equivalent of a grammy.  I tried it on mine last night and it worked perfectly.  What is an N-model?  There was an option to load it.  I have an "A" and my RBW goes a lot lower than others I've noticed.
Title: Re: Advantest R3131 (not A) Spectrum Analyzer 9KHz-3GHz
Post by: konisan on February 14, 2018, 12:26:36 pm
Quote from: SaucySoliton on November 30, 2016, 05:32:30 pm
Quote from: utkuzu on November 29, 2016, 10:27:21 am
I lost my factory default. Could you write me some values? Shift+5 , pass: 882323 , I RF, YTO Tune, Max1stLO and Min1stLO  hexadecimal values. Thanks your helps.

Max1stLO 0x0DA6
Min1stLO  0x0120

I have a R3131, not R3131A.  I have rewrited above Max1stLO and Min1stLO value in my R3131 mistakenly.
Then the self test starts a error at lock detect.
Is there anyone who knows the original value of Max1stLO and Min1stLO for R3131, not R3131A.
How to get the values are the same as above.

Best regards,
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Marcel G on February 14, 2018, 12:53:33 pm
Advantest R3131    serial number: 81780209

Max1stL0:  0X0CC8
Min1stLO:  0X0087

Regards,

Marcel
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on February 14, 2018, 01:34:08 pm
Hello Marcal,

Thank you very much for quick answer to my question.
Though I have used your values, the self test failed unfortunately.
My S/N of R3131 is 81780912.

Again thank you for your information.

konisan
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on February 14, 2018, 06:27:49 pm
Quote from: Marcel G on January 26, 2018, 10:19:34 pm
After a lot of reading on the internet and informing, I managed to replace a damaged 1st mixer of a Advantest R3131.
The original mixer (DMJ 4317-1) is no longer available but has found an excellent alternative by using an HSMS-2822.

Below you see two photos, one with the damaged mixer and a picture with the alternative mixer. Both photos were taken without any RF input. The differences are clearly perceptible.

Probably these diodes can also be used in other older Advantest Spectrum Analyzers, take advantage of them.

In any case, there is exactly the same mixer in the U4342 that I also have.

Small problem with that solution though: The HSMS-2822 is listed as "Last time buy" on Digikey and was declared obsolete by Broadcom in December 2017.
Unfortunately, there's no direct replacement available. Among the diode-pairs with a similar capacitance, the BAT68-04 is the one with the highest reverse voltage (8V instead of 15V).
Schottky-Diodes with reverse voltage higher than 8V all have higher capacitance - usually twice as high as the HSMS-2822.

No idea what that change in capacitance will do to the performance of the mixer, but my guess is that it's not an improvement :)

Quote from: konisan on February 14, 2018, 01:34:08 pm
Hello Marcal,

Thank you very much for quick answer to my question.
Though I have used your values, the self test failed unfortunately.
My S/N of R3131 is 81780912.

Again thank you for your information.

konisan

Most likely, this is a value that needs to be individually set for each YTO. I have a R3131A and the Max1stLO-Value is 0x0DB3, the Min1stLO is 0x00D7. In your case, you probably have to try out a lot of values until you find the right one and the YTO-PLL locks again.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on February 15, 2018, 01:57:49 am
Thank you very much, SaabFAN
Solved!
I remembered that Min1stLO was around 0x0120. So, set Min1stLO:0x0120, then increase Max1stL0 until Lock Detect Pass.
The pass value was 0x0FA0, however it was critical. Sometimes fail, sometimes pass.
Then eventually , I set

Max1stL0:  0X0FB0
Min1stLO:  0X012D  (selftest lock detect pass, several times)

Note) I'm sorry I made a mistake of name of Marcel.

Then another problem :
I have replaced a battery on CPU board, and shiht +9, reload Tracking Generator. It was successful. However,  when TG on, "Error 802:TG Un leveled" message is appeared.  Is there any way to correct it ?

Thank you again.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on February 21, 2018, 09:24:36 pm
When I had the "Error 802:TG Un leveled" message it was because of the bad backup battery. As you just replaced yours, check that your Center frequency is not 0 and the span is not going below 0Hz.
Try 5MHz, Zero Span, or try the Auto button.

I miss my 3131A. If any one has a good TG module schematic I am interested, or troubleshooting guild.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on February 22, 2018, 12:23:14 am
Thank you for the information, IRB-san.

I was tried and failed.
My center frequency can be set at any frequency including 0Hz and the span can go below 0Hz.  And tried 5MHz and 0Hz span, and push Auto Tune button. But Error 802 is the same.

Will you inform me of your step for TG recovery after the battery change?

Thank you again.      Konisan
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on February 22, 2018, 12:46:53 pm
I did not have the issue after the battery was replaced.
I had to cycle power after setting the frequency and span to trigger a save.
I fortunately did not loose the TG function from the memory.

Have you tried the the built in cal (SHIFT then 7) then run all the self cal. Sorry I can be more specific my 3131 is in pieces till I can fix or replace the TG module.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on February 22, 2018, 10:15:33 pm
I have tried Shift+7 and run all the self CAL. But TG on, failed, Error 802 is the same.

IRB, Thank you again.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on May 11, 2018, 01:16:39 pm
OK, I have replaced the power supply fan, it was pulling down the 12V.
I made extensions for the control cables, for the SMB to SMB  and for the copper hard line SMA to SMA.

konisan, to your issue, if I disconnect the copper hard line SMA to SMA, I get the 802 TG un-level error.

I hope this points you in a good direction.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on May 11, 2018, 05:55:34 pm
Does anyone have more pictures of the inside of the TG module form a R3131A?
Or schematic or instructions, beyond the TG AUTO or manual adjustments.

My TG seems to be almost 3.5MHz on the high side, as measured on a 10MHz GPS locked Rigol DSA815, and I need a way to adjust it.

On the R3131A I have verified my internal 10MHz, with a 10MHz GPS locked reference from Jackson LABs. I connected it to the input and set the analyzer to 1GHz turned on the counter, I adjusted the internal reference until I got 1.000 000 012 GHz using the 1GHz(-89db) harmonic form the 10MHz reference.
Cold cycled the 1GHz came back 1.000 000 034 GHz
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on May 14, 2018, 03:55:56 pm
Further testing has lead me to believe there is a pair of varactor diodes, and one maybe bad.
The TUNE voltage from an upper board form a LM833 op-amp powered from +/-12Volts is pushing to -11.24V when I bridge pins 6,7 of the op-amp the voltage went to +10V and the RF frequency went higher. From this I would say the op-amp is working, but something else will not allow the frequency to come into range.

I don't know exactly what these two components are, I believe they are varactors, they are the marked  6.0 on the top edge and L6 on the body. I think there are SOD323?

If anybody knows the component, Please post it or PM me.
   
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on May 14, 2018, 07:31:36 pm
A quick google-search brought up 6.0 Volt Zener-Diodes (Searched for "SMD Code 6.0 SOD323").

Btw. I think, you should open a Thread in the Repair-Subforum. You'll get help there much more quickly and more reliably. Here the thread is too quickly pushed down by general talk about T&M-Equipment.
Also a good opportunity to summarize what you've done so far and what you found out.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on May 15, 2018, 03:22:29 pm
I'm leaning towards this Discontinued Panasonic MA368.
      http://pdf.datasheetcatalog.com/datasheet/panasonic/SKD00037BED.pdf (http://pdf.datasheetcatalog.com/datasheet/panasonic/SKD00037BED.pdf)

I e-mailed Advantest.co two days ago nothing back yet.


Might cross to SMV1408-040LF but wrong footprint(SOT23 or SOD-882)

I also noticed, as I moved my finger around the tuning cavity, it triggered 802 ERROR

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on May 17, 2018, 11:32:47 pm
IRB
Thank you for the TG information. After my last posting, I found the repair company (www.three-re.co.jp/ (http://www.three-re.co.jp/)) for R3131 in Japan, because Advantest is almost no business for spectrum analyzers today. And three-re company has a license to repair for Advantest. So, I asked for the repair of my R3131 TG. Then the answer was that they could not accept to repair because I had replaced the battery inside.
They said if the casing is open, they will not accept for the repairing. I have tried another repair company, but they have no technical skills to repair R3131. Eventually I have purchased the "Rohde & Schwarz SMY01" sweep generator at auction in Japan for US$300. It works very fine as TG so far.
Best regards,
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on September 15, 2018, 12:11:57 am
Hello!

I have purchased a used R3131A through Yahoo auction recently for US$90. It works so-so, but IF STEP AMP test is fail in the self test.
In diag mode (shift+5), actually IF ATT test is fail.
Is there anyone who knows to correct it, such as an adjustment of some pot in IF board etc. ?

Thank you in advance.

Konisan
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on September 15, 2018, 06:56:18 pm
There are some repair instructions floating around. IIRC this problem has something to do with analog switches and ADCs or DACs on the IF board. Under no circumstances you should try to 'adjust' the spectrum analyser unless you know what you are doing.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on September 16, 2018, 12:12:26 pm
nctnico-san

Thank you for your comments. I'm going to find which pot on the IF board should be adjusted. After one hour power on, sometimes IF AMP test is 'pass'. So I think there is a very critical error.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on September 16, 2018, 03:08:22 pm
In my case, I had to change the value of resistor R120 to fix that exact problem.
Normal value is 390 Ohms, I placed a 470 Ohms resistor and now it is working again.
If I remember correctly, there are almost no pots in this instrument. All the adjustments are being done with DACs via the "Shift + 9"-Menu. The device will ask for a password, which you can find somewhere in this Forum-Thread.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: konisan on September 17, 2018, 08:58:23 am
SaabFAN-san
Thank you for the information to correct my problem. I hesitate a little bit to open RF input block. Because I think it is a little cumbersome for me and I am afraid whether it could be restored well. Therefore for the time being, I will use the R3131A under the current condition. Today I'm working to remove yellow rust color from the front panel.   
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Rémi on December 12, 2018, 11:52:06 am
Hi guys,

I'm currently trying to implement a python script to capture the screen of an Advantest R3131A via GPBI. My idea is to retrieve a sweep from the instrument. You can find the GPIB commands in the manual of the instrument : http://www.dudleylab.com/R3131-Manual.pdf (http://www.dudleylab.com/R3131-Manual.pdf) (starting from page 201). I'm using the pyvisa library to retrieve the data. Here is my python code :
Code: [Select]
import visa

rm = visa.ResourceManager()
print(rm.list_resources())
SA = rm.open_resource('GPIB0::8::INSTR')
print(SA.query("*IDN?"))
print('Start frequency = ' + SA.query("FA?"))
print('Stop frequency = ' + SA.query("FB?"))
SA.query("CONTS")  # set sweep mode to normal and full
print('Sweep mode = ' + SA.query("SWM?"))

SA.query("TS")  # reset and take sweep
SA.query("TM FREE")  # set trigger to free run mode
print('What updates memory A at each sweep (0=write, 1=view, 2=blank) ? ' + SA.query('TA?'))
SA.query('AV')  # Send A view command
# query to retrieve sweep
test = SA.query_binary_values('TBA?', datatype='H', is_big_endian=True, container=list, header_fmt='empty', expect_termination=True)

print(len(test))
print(test)

rm.close

And this is what I get in the console :

Code: [Select]
('ASRL1::INSTR', 'ASRL3::INSTR', 'GPIB0::3::INSTR', 'GPIB0::8::INSTR')
ADVANTEST,R3131A,01780698,C00
Start frequency = +9.00000000000E+03
Stop frequency = +5.00000000000E+07
Sweep mode = 0
What updates memory A at each sweep (0=write, 1=view, 2=blank) ? 1
501
[0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0]

I only receive 0 data, but the length of 501 is correct, does anyone have a hint ?

Thanks!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on December 13, 2018, 04:03:15 pm
I've received data from an R3131a so I know it works.  For some reason though, I thought I used ascii data.  If anything is wrong it would be in the data conversion of the received bytes.

I'll look around for my code, though it was in visual basic, it should still apply.

Jerry
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Rob_Gr on January 09, 2019, 10:38:06 am
Hi  fellow Advantest3131A owners
I have an Avantest R3131A without a TG.

It worked ok. But then It quit working. The SA froze and did not respond to keyboard input.
After switching off and on it worked again. A week later at startup it gave an “RTC data error” at the selftest.
The CPU battery was dead, so I replaced it with two penlite batteries.
Now the SA passes its selftest and then displays UNCAL. It does not respond to any keyboard input.
I tried pressing the button on the CPU board. After pressing the SA restarts, goes thru its selftest again and again displays UNCAL.
Any help in solving this would be much appreciated.

Rob
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on January 09, 2019, 11:50:28 am
Did you press the button on the mainboard while switching it on? Does it respond to the keyboard again?
The uncal probably goes away after doing a self calibration. This is simple: connect the cal output to the RF input and let the SA run the self calibration.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on March 09, 2019, 02:42:07 am
At long last I had some time...

Thank you Fraser, thank you RadioAct, and all the contributors, for all the information, pictures, schematics, testing, data and instructions.

I went through almost all of it... Directly controlling the varactors  proved I was on the right path, and the TG could be saved.

I do not have a good way to measure the 3840MHz, so I set the tracking generator to 500MHz -40dbm feed that in to a Rigol DSA815 with a 10MHz GPS reference.

I have what was called the "Type 1 early" Advantest tracking generator. But the ugly kind with no adjustment arm, just a 1206 0 Ohm resistor to move around...  back and forth all around, it did not help, the VCO stayed at -11.21Vdc...

I built up solder, then I wicked away solder. 

Finally I decided to stack a capacitor on top of C312 to simulate moving the dielectric trimmer. 
See Fraser's pdf:   https://www.eevblog.com/forum/testgear/advantest-r3131a-spectrum-analyzer-9khz-3ghz/msg864931/#msg864931 (https://www.eevblog.com/forum/testgear/advantest-r3131a-spectrum-analyzer-9khz-3ghz/msg864931/#msg864931)

Measurement at TP401 "TUNE", with cover held on by gravity
-11.21V with 0.5pf   -5.21V with 2.0pF    -5.70V with 4.7pf   -9.83V with 15pF,   -10.18V with 22pf    0805 Package

I am staying with the 2.0pF, I don't know the original value of C312 but this gives it some swing the op-amp is running of +/-12V

For any one having low +12V, check the power supply fan, mine was pulling down the +12V supply.

While typing this the VCO has moved to -5.38V and holding the 500MHz it is set to.
After a Self Calibration the voltage is -5.51V~-5.52V.
Next is to put it all back together and see if it stays working.

Again thank you all for the information.


Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: stellavox on June 28, 2019, 08:40:41 pm
Hello,

I appreciate all the work you have done for the 3131. 

I just got one and replaced the battery per the info in this thread.  Working my way thru the pass/fail tests.

The TG in the unit doesn't work and the main connector wasn't plugged in.  anyone have any info on it and where to begin to service.

THANK YOU
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on June 28, 2019, 09:52:52 pm
The TG can be enabled in the Service-Menu. If I remember correctly, it was SHIFT + 5 and the Password should be somewhere in this thread here if its not 232355.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: stellavox on June 29, 2019, 12:42:45 pm
Thanks Saabfan,

The function IS enabled but I get an error message that the output is not levelized, and I believe there is no output at all.

Looking for some kind of block description on what goes on inside the TG module so I have a place to start troubleshooting.

Charles
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: SaabFAN on June 29, 2019, 01:38:31 pm
Try running the calibration-routines in the service menu. With the battery empty / replaced, you have probably lost most cal-data.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on July 12, 2019, 08:29:53 pm
Quote from: stellavox on June 29, 2019, 12:42:45 pm
Thanks Saabfan,

The function IS enabled but I get an error message that the output is not levelized, and I believe there is no output at all.

Looking for some kind of block description on what goes on inside the TG module so I have a place to start troubleshooting.

Charles

If you have access to to another spectrum analyzer, connect the 3131 TG out to its input, I found the TG tuning was so far off even at full span the sweep was unable to see the TG output.   

You could try the SELF CAL press the "SHIFT" (Blue Button) then press the "CAL" or 7. Run the "Cal all" by pressing the soft key to its right.
 

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on July 17, 2019, 03:17:06 pm
Quote from: stellavox on June 28, 2019, 08:40:41 pm
Hello,

I appreciate all the work you have done for the 3131. 

I just got one and replaced the battery per the info in this thread.  Working my way thru the pass/fail tests.

The TG in the unit doesn't work and the main connector wasn't plugged in.  anyone have any info on it and where to begin to service.

THANK YOU

On the Tracking Generator module there is an SMA connector and a SMB connector, along with the ribbon cable. If thse ar not connected then the T.G. module will not work properly.

When I had the SMA cable disconnected I got a 802 TG un-level error.

In the picture below, there is a feed through in the lower left corner of the lower left compartment, this voltage should be close to 0V. It should be between +12V and -12V. It is the same point as the test point "Tune".     
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: dc8wan on January 05, 2020, 11:24:53 pm
Hello,

I search for the partnumber from the "PROBE POWER terminal". An the CPU
The Manufacturer is LEMO.
I don't find any information over this connector.

regards Marco
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: dc8wan on January 06, 2020, 10:45:40 am
Hi,

have found the partnumber from the connector.
FFA.0S.304.CLAC42

Source http://w140.com/tekwiki/wiki/LEMO_S-series_connector (http://w140.com/tekwiki/wiki/LEMO_S-series_connector)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Lars2 on September 23, 2020, 01:19:10 pm
Hi,

I have some trouble with the TG of my 3131A. It seems to be the know problem with the 2nd LO frequency. My question: what is the frequency supposed to be? The information posted in this thread say it is 3840MHz but the frequency is always posted in conjunction with the 3132. I am asking because I measured the frequency using a near field probe and a scope and got a value close to 4.1GHz. Also the silk screen on this particular area also says "4.1G". Does that mean, that the 2nd LO in the 3131A is supposed to be 4.1GHz? or is my TG that far of?

Regards

Lars
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: conmega on February 27, 2022, 03:11:05 pm
Quote from: Fraser on February 04, 2016, 11:55:07 am
Just remembered, I uploaded my 2nd LO adjustment guide to the Advantestinstrument Yahoo Group. You can download it from there. Its over 1MB so cannot be attached here.

https://groups.yahoo.com/neo/groups/advantestinstrument/files/-%3DAdvantest%20-%20R3132%3D-/

UPDATE & WARNING

Please read all of this thread. It has become apparent that two versions of R3132 RF module were made. My newer modules use a dropper resistor in series with the 2nd LO MMIC and buffer MMIC supply rails. Earlier versions of the RF Module do not contain this dropper resistor ad use a lower supply voltage to the MMIC's. This thread contains details of teh lower voltage level measured by a fellow forum member.

Fraser

Hey Fraser,

Would you happen to still have this doc now that Yahoo Groups is dead?
I got a pair of R3132s cheap at a swap meet locally. Looks exactly like the 2nd Stage VCO has drifted.
Been reading through the thread but haven't seen a secondary source for that alignment doc you made yet.

If you could make that available again I'd appreciate it!

Thanks,
-Connor K
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: rainbow on March 16, 2022, 03:15:04 pm
Quote from: conmega on February 27, 2022, 03:11:05 pm
Would you happen to still have this doc now that Yahoo Groups is dead?

I got a pair of R3132s cheap at a swap meet locally. Looks exactly like the 2nd Stage VCO has drifted.

You can find it at https://groups.io/g/advantestinstrument/files/-=Advantest%20-%20R3132=- after group subscription.
Just as a metric (if you can say): how much have you paid the not working R3132?

I have an R3131 without TG and I would like to add it if I find one at reasonable price (working or broken) from a spare device. If someone has that feel free to contact me privately. Thank you.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: [steven] on October 15, 2022, 02:24:03 pm
Hello everybody,
I got an advantest r3131  a few weeks ago, I already replaced the battery and also replaced to floppy drive for a gotek flopppy emulator.
But I still have one problem with the tracking gen.
When enabling the tracking gen in the menu (which I unlocked using the pwd) I cant see the signal in the spectrum appearing.
I've already attached an RF transmitter transmitting at static carrier to the input of the analyzer, this works fine and is also at the expected frequency.
I've also attached the tracking gen to an oscilloscope and this shows the expected up chirp in the time domain.
So the RF output and input seem to be working but connecting both to each other doesn't.
However I do see the following in attachment 1.
Multiple peaks at a negative frequency? (which also confuses me, a negative frequency is only possible in mathematics right?)
When detaching the tracking gen I get what can be seen in attachment 2.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: cncjerry on October 18, 2022, 04:48:31 am
I'd have to look at mine, but you are centered on zero hz with any span you are potentially going to see the peaks below zero, but I agree, they shouldn't be there but you shouldn't be centered on 0hz either.

did you turn on the TG?  you have to run the cable from output to input and then turn it on in one of the settings.  If you have it enabled in the operator menus, have the hardware in your analyzer, enabled in firmware, and still don't see a trace, then the TG output it shot.  nothing unusual as many people hook outputs to outputs and blow one or both.  I don't remember if anyone ever found a service manual for a 3131?

one other thing to try, after you are sure you have the Tg turned on, use a scope to see if there is any RF coming out the Tg port.  It might not be sweeping.  Again, I cant remember, but when testing, keep the RBW and VBW on coupled (not manual) because some analyzers have limits in RBW when using a TG.

Jerry
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on October 18, 2022, 10:21:35 am
In addition to the useful tips of cncjerry: One more thing to try is to hold the button on the mainboard during power up. I used to own an R3131 myself and after replacing the battery it wouldn't start. Holding the button on the mainboard during power up restored normal operation. I assume it does some parameter reset. Long shot but worth a try.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: [steven] on October 19, 2022, 08:10:50 pm
Thanks for the replies. Checked it with an o'scope, turns out my TG has an offset by almost 22 MHz.
Probably the same issue that was reported by other people.
Already did the mainboard switch trick, didn't work unfortunately.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: dtxy101 on December 02, 2022, 10:10:13 am
At long last I had some time...

Thank you Fraser, thank you RadioAct, and all the contributors, for all the information, pictures, schematics, testing, data and instructions.

I went through almost all of it... Directly controlling the varactors proved I was on the right path, and the TG could be saved.

I do not have a good way to measure the 3840MHz, so I set the tracking generator to 500MHz -40dbm feed that in to a Rigol DSA815 with a 10MHz GPS reference.

I have what was called the "Type 1 early" Advantest tracking generator. But the ugly kind with no adjustment arm, just a 1206 0 Ohm resistor to move around... back and forth all around, it did not help, the VCO stayed at -11.21Vdc...

I built up solder, then I wicked away solder.

Finally I decided to stack a capacitor on top of C312 to simulate moving the dielectric trimmer.
See Fraser's pdf: https://www.eevblog.com/forum/testgear/advantest-r3131a-spectrum-analyzer-9khz-3ghz/msg864931/#msg864931 (https://www.eevblog.com/forum/testgear/advantest-r3131a-spectrum-analyzer-9khz-3ghz/msg864931/#msg864931)

Measurement at TP401 "TUNE", with cover held on by gravity
-11.21V with 0.5pf -5.21V with 2.0pF -5.70V with 4.7pf -9.83V with 15pF, -10.18V with 22pf 0805 Package

I am staying with the 2.0pF, I don't know the original value of C312 but this gives it some swing the op-amp is running of +/-12V

For any one having low +12V, check the power supply fan, mine was pulling down the +12V supply.

While typing this the VCO has moved to -5.38V and holding the 500MHz it is set to.
After a Self Calibration the voltage is -5.51V~-5.52V.
Next is to put it all back together and see if it stays working.

Again thank you all for the information.



 :-+Is the test normal after TG repair?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on December 13, 2022, 05:37:13 pm
Quote from: [steven] on October 19, 2022, 08:10:50 pm
Thanks for the replies. Checked it with an o'scope, turns out my TG has an offset by almost 22 MHz.
Probably the same issue that was reported by other people.
Already did the mainboard switch trick, didn't work unfortunately.

I see "dtxy101" re-posted my repair.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: [steven] on December 31, 2022, 09:24:41 pm
First of all happy new year everyone.
Sorry for my late reply, I've a bit busy with some other things.

I've taken out the RF board from the SA and removed the shielding from the TG.
As far as I understand there are two versions of the TG, how do I recognize this and where would the adjustment arm be?
Also where is TP401 located?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: IRB on January 11, 2023, 08:03:57 pm
Quote from: [steven] on December 31, 2022, 09:24:41 pm
First of all happy new year everyone.
Sorry for my late reply, I've a bit busy with some other things.

I've taken out the RF board from the SA and removed the shielding from the TG.
As far as I understand there are two versions of the TG, how do I recognize this and where would the adjustment arm be?
Also where is TP401 located?

Steven, you have the "No arm" version, like I have. Look several post above this. I have two images, zoom in on the picture that is not the inside of the tuning section, there is silkscreen says "TUNE" in white lettering, that is TP401 also "P2"

It's been a while, so I'm not sure it might also be the blue wire "VTUNE" <- you will need to check this!

I suggest you get some low value SMT Caps, and try soldering them in parallel with C313(My board did not have a designation for the cap)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: [steven] on January 12, 2023, 10:27:39 pm
Thx for your reply. I've measured VTUNE which is at -11.19V, very similar to your TP401 voltage. As a first try I completely removed my tuning resistor. And my TG works now! VTUNE settles around -6.30V after a while and my TG output frequency also seems to be spot on.
Thanks for the help!
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: pmax65 on January 22, 2023, 05:15:36 pm
Hi there,
since I repaired my very early R3131, but the reference signals are almost the same for the later R3131A version, I believe that somebody could be interested to the pdf files I did for the RF board and the RF sampler boxed block.
These files are the images of the RF board with superimposed the nominal signals values for almost all the significant points of the RF board functions itself.

At the bottom right of the picture into the RFsampler_measurements.pdf file, you can find the values for the 4th IF variable amplifier that is the "thorn in the side" of the instrument along its ageing.
Those value are the original ones for the very early Japanese instruments (the R3131 not A), but following Analog Devices datasheets they are better than the values used later in R3131A version. It seems that Advantest engineers didn't a good job designing that amplifier, and they did worse trying to do it better indeed.

The values shown below "Modded version for extended gain" are those I changed to those of the final production values (the "R3131A" version) to extend and center the gain and definitively fix the issue.
For that components setup I got a 9dB to 26.6dB range for the whole 12 bits DAC output codes (from 0000h to 0FFFh), with the middle gain of 20.8dB @ [RF] > [IF Amp] > [OFS ADJ] = 0800h

I hope you get aid from these files and you could fix you R3131 easily.

Massimo

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: flolic on February 23, 2023, 01:14:43 pm
After resetting to defaults (Shift + Config keys), my R3131 is showing level in dBμV instead of dBm. That started after replacing bad internal Lithium battery.
I can change units back to dBm in Level menu, but it will revert back to dBμV after every reset.
Is there a way to change default configuration?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: rainbow on March 08, 2023, 01:15:28 pm
Quote from: flolic on February 23, 2023, 01:14:43 pm
I can change units back to dBm in Level menu, but it will revert back to dBμV after every reset.

Have you reset the config using the device button in the motherboard during power on?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: flolic on March 08, 2023, 08:25:08 pm
I honestly don't remember, I replaced battery few years ago.
Do you think that resetting the device via the button can fix the problem?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: rainbow on March 08, 2023, 08:49:38 pm
I don't know ;-) If you have already checked the manual I don't know others ways to reset the configuration.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: flolic on March 11, 2023, 08:04:05 am
Just for the reference, I have tried motherboard reset button but it's the same as before. Never mind, it's not really a problem.
OTOH, SA does not pass self test every time when warm, it will fail in Total gain test. Calibration fail with IF step amp error. So, time to replace 4072 opamps and analog switches.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: rainbow on March 11, 2023, 03:53:44 pm
Have a nice repair ;-)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: dtxy101 on May 20, 2023, 10:14:30 am

  Hello, everyone, I am repairing my R3131A. My TG output frequency has shifted by 14MHZ. After removing the adjusting resistor of VCO (a 0 ohm 0805 patch resistor), the frequency output returns to normal, and the frequency output is normal from 10MHZ to 1.8GHZ. However, there are still faults: the output of TG signal is not linear, and there are several points where the output jumps, for example, 0 DBM-9.9 DBM is set, and the maximum output is -30DBM. When the knob is lowered, the output gradually decreases. Set-10 DBM-19.9 DBM, and the maximum output is -15DBM. When the knob is turned down, the output gradually decreases. Check that there are 3 ATT circuits on the PCB:-10 dB att; -20DBA ATT ; -20DBB ATT ; TG signal output attenuation switching failure?
Who has a picture of the PCB of TG output part, three resistors of 10DB ATT, two of which are 100 ohms, and how many ohms is the other one? I can't see this one clearly.
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: dtxy101 on May 25, 2023, 12:43:59 am
What is the resistance of the resistor in the red circle?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: nctnico on May 25, 2023, 09:27:48 am
It is a pi-pad attenuator so you can derive the value:
https://www.electronics-tutorials.ws/attenuators/pi-pad-attenuator.html (https://www.electronics-tutorials.ws/attenuators/pi-pad-attenuator.html)
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Renaud F5ZR on August 17, 2023, 04:40:06 pm
Hi,
I'm new here. I just bought a R3131 in need of work.
I downloaded two Operation Manuals
FOE-8311227H00 Dec. 1 1997
FOE-8311227D02 Dec. 1 1997
They are quite different. Any comment about them?

Also one Maintenance Manual:
FME-8335142B00
As I will print them (having them printed rather!) I'd prefer to choose the right one first. Of course I will need the serial # of mine when I receive it.
This was just to introduce me and my new toy.
I read all of this remarquable post from the beginning when I was looking for a R3131 but I probably should have opened a new one, sorry.
Renaud
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: Renaud F5ZR on August 20, 2023, 07:19:55 am
I'll answer my own questions above myself.

Now that I have read the Advantest docs I understand why nobody took the trouble to do it.
Even if I read all this post from the beginning the newbie could not believe the Maintenance Manual was of no use at all.
Now I do!
Renaud F5ZoulouRadio
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: ABC on September 04, 2023, 02:31:53 am
Hello everybody,
My R3131A has an error as shown in the figure. Where is the fault? Which board is broken, please advise!

Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: ARF on October 27, 2023, 11:48:02 pm
I'll refresh the topic.
I recently received a R3131 and replaced the battery.

Like many others, self-testing falls on “Total Gain” and auto-calibration falls on “IF STEP AMP”.
I've seen a method of replacing the resistor and adding +2dB this way. But this is a hack..

Has anyone found the real cause of this problem?
Title: Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
Post by: ARF on October 30, 2023, 09:46:39 pm
Quote from: marshallh on July 02, 2013, 05:14:17 am
Fixed.

(http://imageshack.us/a/img208/2295/uh6.jpg)

The issue was in the 4th section of the IF/LOG board. I replaced the AD606 log opamp (a $40 part) and it was not failing as bad - there was a small amount more gain in the stepamp test stage.
I then replaced the AD826 opamps after that. No change. Then I replaced the two 4072 opamps at the very tail end of the IF board. These drive the signal through the backplane connector onto the ADC / CPU board where it is digitized. Replaced both here and the problem was fixed.
The original is an ON Semi 4072 family, my replacement was MC34072DR2G.

After running warm for an hour it still passes with flying colors.

Thanks to everyone for your support

I tried it. I replaced them with a TL082 - which has exactly the same internal design as the 4072. I got exactly the same thing. If I disable calibration, then my device has a lower level by 5 dBm, which is of course beyond the possibility of compensation. The problem is located before the IF unit, of course.