Advantest R3131A Spectrum Analyzer 9KHz-3GHz

[Fraser]

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

[jc81382]

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.

[Fraser]

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

[Fraser]

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

[CJay]

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?

[Fraser]

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

[Fraser]

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

[jc81382]

is that a component that can be easily purchased and possibly replaced?

[jc81382]

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)

[Fraser]

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

[jc81382]

Hmmm... I wonder if i should just look for a replacement module on e-bay or something.

[Fraser]

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

[Fraser]

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

[CJay]

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.

[Cech]

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 
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

[nctnico]

Can you post this somewhere?
I suggest this website: http://www.ko4bb.com/getsimple/index.php?id=manuals

[cncjerry]

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 
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!

[Cech]

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 
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

[utkuzu]

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 
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?

[utkuzu]

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 
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

[SaucySoliton]

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!

[utkuzu]

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.

[nctnico]

AFAIK you should be able to do a self calibration to get all these values right.

[utkuzu]

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.

[nctnico]

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.