Author Topic: Advantest R3131A Spectrum Analyzer 9KHz-3GHz  (Read 87402 times)

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Offline marshallh

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Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« on: June 11, 2013, 09:43:38 pm »



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.







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)








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






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.






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.








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







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






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.






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.
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Offline nctnico

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #1 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://www.digital-circuitry.com/MyLAB_Bench.htm
http://groups.yahoo.com/group/advantestinstrument/message/75

It seems you need to replace two DACs to fix your problem.
« Last Edit: June 11, 2013, 10:22:08 pm by nctnico »
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Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #2 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.
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Offline Fraser

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #3 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.
 
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Offline Fraser

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #4 on: June 11, 2013, 11:16:20 pm »
I just found some pictures that I took of the 3131 RF module whilst repairing it.
« Last Edit: June 11, 2013, 11:51:28 pm by Aurora »
 
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Offline Fraser

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #5 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'.
« Last Edit: June 12, 2013, 12:02:19 am by Aurora »
 

Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #6 on: June 13, 2013, 08:28:39 pm »
Thanks for the pics. The 3132 RF section is really a quite different layout.
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Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #7 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
« Last Edit: June 13, 2013, 09:16:04 pm by marshallh »
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Offline nctnico

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #8 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.
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Offline ve7xen

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #9 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?
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Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #10 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"
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Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #11 on: June 14, 2013, 02:12:05 am »
The shielded parts of the RF pcb:

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
« Last Edit: June 14, 2013, 02:33:45 am by marshallh »
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Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #12 on: June 14, 2013, 03:24:13 am »
R3261 block diagram:


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.
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Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #13 on: July 02, 2013, 05:14:17 am »
Fixed.



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
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Offline Fraser

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #14 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.
« Last Edit: July 02, 2013, 10:55:30 am by Aurora »
 

Offline marshallh

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #15 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.
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Offline Fraser

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #16 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.
« Last Edit: July 02, 2013, 07:51:24 pm by Aurora »
 

Offline G0HZU

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #17 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.
« Last Edit: July 02, 2013, 07:41:14 pm by G0HZU »
 

Offline Fraser

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #18 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


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.
« Last Edit: July 02, 2013, 10:22:01 pm by Aurora »
 

Offline G0HZU

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #19 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 :)
« Last Edit: July 02, 2013, 09:39:36 pm by G0HZU »
 

Offline nctnico

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #20 on: July 02, 2013, 09:46:24 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!).
There are small lies, big lies and then there is what is on the screen of your oscilloscope.
 

Offline G0HZU

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #21 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/faq.htm

« Last Edit: July 02, 2013, 10:15:30 pm by G0HZU »
 

Offline Fraser

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #22 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.
« Last Edit: July 02, 2013, 10:43:46 pm by Aurora »
 

Offline G0HZU

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #23 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.



« Last Edit: July 02, 2013, 11:31:30 pm by G0HZU »
 

Offline RFasic

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Re: Advantest R3131A Spectrum Analyzer 9KHz-3GHz
« Reply #24 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 ?



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

Thanks for this coming knowledge, AURORA !
 


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