Repair of Anritsu S332D

[m0vse]

Hi all.

I have an Anritsu SiteMaster S332D that had been in the wars!

After replacing the cracked screen and missing battery, it also fails the self test with "Integrator Failed" error which has me stuck.

I contacted Anritsu and they wanted lots of money (many £100s) just to look at it so I politely declined.

Does anybody have any experience with these and can give me some pointers where I could look? The spectrum Analyser function seems to work OK but I was really hoping to use it for testing a 2.4ghz patch antenna.

edit: I realise this probably means that somebody has injected high RF into the device at some point!

Thanks

Phil Taylor

[metrologist]

I will help you.

Can you open the case and take a picture of the area where the input coax terminates to the PCB? Also, if you can follow the incident path to the first stage amp and tell me the chip marking.

[m0vse]

Great, thanks for your reply. The RF input enters the main PCB underneath a large metal can which covers both the front and back of the PCB. I have removed the can and this is what was beneath it (from both sides).

Phil

[m0vse]

The previous pictures are of the RF output section (marked RF Out / Reflection on the socket). As the spectrum analyzer part of the unit seems to work OK I thought that the input was OK? What do you think.

I have removed the (gold coloured) can from the input section and a pic of this is attached.

Thanks

Phil

[metrologist]

What is the main board number and rev? They look a bit different. The spa board should be fine.

Usually when these are overpowered, like plugging into a powered cell station, the area below the ferrite beads is charred. I did not see signs of burning there. The amp was sensitive to static - so that could get zapped when connecting an antenna.

[m0vse]

Thanks, I will check those and report back.

The mainboard is 64968-3 Rev E_/A

Phil

[metrologist]

If you want to probe the RF path, you can set CW mode...

[m0vse]

I get nothing when trying any of the sweeps, they run very slowly and nothing registers on the display.

I have a 1Ghz spectrum analyzer that if I connect it to the n-type socket, I can see the signal sweeping up (slowly) so it is obviously generating something?

It looks like the component numbering is different to what you are quoting as other than TP13 (marked INC_IF) I have different numbers for everything!

What would I expect to see at TP13?

Thanks again for your help!
Phil

[metrologist]

Incident IF. You should also find the REFL_IF. I think it might be easier to look at that if you set Meas to Fixed CW and then set F1=F2 (I think that changes it from FDR to TDR). You can check the amps and diodes along those RF paths.

[m0vse]

Hi.

When in Fixed CW, at both test points TP13 (INC_IC) and TP14 (REFL), I can't see any significant RF at the frequency that I have set (50Mhz). I can see quite a strong 50Mhz signal on the output.

I have started to trace the circuit around the RF IN/OUT in an attempt to understand how it works but many of the components have quite obscure markings that I can't find!

SW1 which is marked S218/4895/529 is one and also U70, just below both TP13 and TP14 is marked just D/OQ (it is a 10pin SOIC) with connections to both test points. It is above U7 and U124 which are both AD8042AR and U24 which is an LTC1562.

There is also U109 which is labelled H187/8699 and another which just says A5RAD on the top.

Any pointers on the above would be greatly appreciated!

Phil

[m0vse]

After a bit more "probing around", it looks like the MCL25 may not be working. I can measure 50Mhz on the input pin (3) but there is nothing on the output pin (6)

[metrologist]

I assume you see your signal on the semi rigid soldered to the PCB on both sides of the bead. What do you see on that blue cap to the right of SW1 in your pic? That looks like it goes off to the upper right. I see a duplicate circuit on the other side of the PCB.

[m0vse]

Yes I can see it on the semi-rigid and the blue component (which I think is a 50r resistor) and the cathode of the pin diode (PM2) and all the way over to the NPN transistor (C2T)

Phil

[metrologist]

You should see signal on TP29, which I see in your second photo. There should be a couple transistors in each path before the LTC1562 that you mentioned.

[m0vse]

Yes I can see the signal at TP29. Do you think it is worth replacing the chip marked MCL25? (it is a Mini Circuits VNA-25+ I think). I can see it is getting a bias voltage of 3.3v but there is definitely no signal at the output.

Phil

[metrologist]

That part is rated up to 2.5 GHz. The signal path should accommodate the frequency range of the instrument. I think if you are looking at low frequency you are not down converting your IF.

Can you post a picture of the board area or trace the signal path to the next component from TP29.

[m0vse]

Here is the same area from both sides, it isn't immediately clear (to me) where the signal goes so I thought I would post both!

[m0vse]

The picture of the rear of TP29 isn't that clear so here is another one which is hopefully a bit better!

[metrologist]

It looks like in the first new pic, it goes to the left and there is something under the black coax. Not sure if that is coming or going there, but you should be able to find the next component using a continuity test. It is probably the next active component in the path that got zapped by static or something.

[m0vse]

Yes TP29 is fed from a transistor which (according to the markings) looks like a BCW68GR. In-circuit testing was inconclusive so I have ordered some replacements from Farnell. The next active component looks to be a MMBT5087 so I have ordered some of those as well.

Thanks

Phil

[m0vse]

Sorry not had much time to look at this for the last few days. I have tried replacing a couple of the active components but no joy yet!

Phil

[metrologist]

To recap, do you see signal at TP29? What signals do you see on the transistor at VT1 and the one on the way there?

[R4PBE]

Заменил VNA25, но безрезультатно, так же ошибка.

[Pattymorr]

S332C with PLL error.

Unable to find schematic somewhere or  a guide for the PLL circuitry path

Pictures under coaxial  TP23 : I_ERR, TP46 : 12 , TP42 : +2.5A (which is actually 2.5V reference)

Seems like the VCO is  the square can on second picture top left surrounded on left by RF switches MSWT-4 -20 and on topt by 2 PLL Ic's LMX2320. The reference on shiny box is  Z-Com V585ME30. None of the PLL had a valid signal on the Xtal input. There is a main LMX2330  PLL with a 6Mhz  Xtal Colpttis configuration single transistor on pin 1 which was unable to oscillate.  Found a resistor 511R to ground open as part of a voltage divider going to the PLL; conveniently, the resistor turns it self in to a 10pf Capacitor which was enough to attenuate all the oscillation. Replaced the resistor and a factory reset gave the instrument a Pass on the self test.

Patty

[vishaldotgupta]

hi

I have been repairing similar equipment on component level.  you need to start step by step.

1. Is RF available on Test port.  if not or low level, mostly you get message integrator failed.  check  voltages on MMIC.  also check for different bad RF Switches.
2. if available, please make the equipment run on zero span on different frequencies to check on spectrum on freq value and level.  If the freq is not correct, problem is with VCO, PLL tuning voltages,  check for mosfets around VCO, OP amps for tuning voltages
3. basically the equipment mixes the generated RF to generated two separate paths of around 400 KHz.  One is called reference, other is measured or rfl value.  if the equipment still doesn't sweep, check for reference path for mixer, Active RC filter (from linear), op amps of AD, and finally to A/D converter from Maxim / AD

you would also like to check voltages on A/D converter.

hope this was helpful

my experience says mostly, RF Switches, MMIC, Mixer, MOSFET switches, etc gets faulty

Trust this was helpful