help needed to repair HP spectrum analyser

[kenramesh]

Hello guys,

i need help desperately to repair my HP 8594A spectrum analyser. 

Pls help me .

Thanx u all.

[mrf245]

what's wrong with that?

[BravoV]

Here the solution -> https://www.eevblog.com/forum/repair/repairs-of-hp-8594a/

[kenramesh]

hi

the link u mentioned was my first post 

thanx for the reply

[BravoV]

hi

the link u mentioned was my first post 

thanx for the reply

DO NOT make new duplicated threads for the same topic, you're SPAMMING the forum. 

[SaabFAN]

The fact that removing the counter-cable is improving the speed suggests that something is wrong with that circuit.

That something connected to the YIG is getting warm is normal. That thing requires quite a bit of current to generate the magnetig fields.

[Bud]

Slow speed - did you try setting tracescan time and resolution bandwidth to faster and wider values?  Sounds normal behaviour to me if they are set too tight.

FREQ UNCAL also may be a operational error- look up in the manual when it is displayed.

All in all do you know how to operate this SA in the first place?

[Simon]

You won't get any responses unless you post a sensible question to which the answer is not an entire book because it is so vague (the answer to "how does this processor work" is a 500-2000 page datasheet for example). You need to explain in as much detail what you need and if it is a repair exact symptoms and what you have done so far.

[krish2487]

Just step back for a moment and look at the issue.

I checked all the settings of the SA, all are normal . Iam using HP 8590L spectrum analyser (BW=1.8GHz) whereas 8594A is 2.9GHz. FREQ UNCAL is always present on the screen from power-on to power-off of the unit.  As i mentioned earlier if i try calibrating the unit using CAL OUT , immediate result is SIGNAL NOT FOUND along with SRQ110 error. preset the instrument the same display FREQ UNCAL. When i remove the flatcable of Counterloack board the FREQ UNCAL disappears ( either the board is faulty or circuit is incomplete due to its removal )yes i know how to operate SA , Iam using HP 8590L, HP 8593E (BW=22GHz),  front keys operation of all the 3 SA's are same.

If you were at the other end and someone asked you the same question and gave you precisely this information. Would you be able to help them?? or even understand what is it that they are trying to communicate about the perceived problem or the instrument itself??


Help us help you.


Please start explaining what is that you have done, what is the problem you are seeing, what have to done to identify the issue behind and where is it that you have hit a road block? - in crisp, concise, complete statements.


People are very helpful here. Any motivation to help you will vanish quickly if you are perceived to be another spammer or a person who is out to waste their time.

[kenramesh]

what's wrong with that?

1.As the instrument is switched on , FREQ UNCAL is displayed which is a permanent fixture.
2.When i try  to calibrate using CAL OUT the result is  SIGNAL NOT FOUND & SRQ110.
3. The trace line is slow in movement , data entry response also appears to be slow.

I couldn,t find service manual for 8594 series , but tried using 8590 series one.

As per that manual either A7 analog pcb, A16 processor , counter lock , or YTO may be faulty but not able to zero-on by using this manual.

I observed the following:

1.on A7 analog interface board Q1 is getting warm
  but if  cable running to YTO removed from the PCB, heat is normal.

2. FREQ UNCAL disappears & trace line moves fast when Counterlock board flat cable is removed

[kenramesh]

The fact that removing the counter-cable is improving the speed suggests that something is wrong with that circuit.

That something connected to the YIG is getting warm is normal. That thing requires quite a bit of current to generate the magnetig fields.

u r right. In fact service manual is not available for this modelto come to a conclusion.

 I tried to find fault using 8590 series manual. As per the manual either A7 analoginterface or processor A16 or Counterlock A25 ( if option available )to be suspected.

Not able to find troubles hooting chart for A7/A16/A25 boards. Schematics for the same r not available.

[kenramesh]

Slow speed - did you try setting tracescan time and resolution bandwidth to faster and wider values?  Sounds normal behaviour to me if they are set too tight.

FREQ UNCAL also may be a operational error- look up in the manual when it is displayed.

All in all do you know how to operate this SA in the first place?

I checked all the settings of the SA, all are normal .

 Iam using HP 8590L spectrum analyser (BW=1.8GHz) whereas 8594A is 2.9GHz.

FREQ UNCAL is always present on the screen from power-on to power-off of the unit. 

As i mentioned earlier if i try calibrating the unit using CAL OUT , immediate result is SIGNAL NOT FOUND along with SRQ110 error.

preset the instrument the same display FREQ UNCAL. When i remove the flatcable of Counterloack board the FREQ UNCAL disappears ( either the board is faulty or circuit is incomplete due to its removal )

yes i know how to operate SA , Iam using HP 8590L, HP 8593E (BW=22GHz),  front keys operation of all the 3 SA's are same.

[kenramesh]

hi

the link u mentioned was my first post 

thanx for the reply

DO NOT make new duplicated threads for the same topic, you're SPAMMING the forum. 

this topic : https://www.eevblog.com/forum/repair/repairs-of-hp-8594a was made on April 17, 2018 but since I got no response,
 i made this one again .

[krish2487]

Exactly what BravoV was trying to gently inform you. When there is no response to a thread, the forum etiquette is to "bump" the same thread or update the status or your efforts or information. Not to create a new thread. 


PS: Same with the responses, it is much much easier if you responded to all the points in one reply instead of staggering each quote and rebuttal answer in a separate post.

[kenramesh]

Just step back for a moment and look at the issue.

I checked all the settings of the SA, all are normal . Iam using HP 8590L spectrum analyser (BW=1.8GHz) whereas 8594A is 2.9GHz. FREQ UNCAL is always present on the screen from power-on to power-off of the unit.  As i mentioned earlier if i try calibrating the unit using CAL OUT , immediate result is SIGNAL NOT FOUND along with SRQ110 error. preset the instrument the same display FREQ UNCAL. When i remove the flatcable of Counterloack board the FREQ UNCAL disappears ( either the board is faulty or circuit is incomplete due to its removal )yes i know how to operate SA , Iam using HP 8590L, HP 8593E (BW=22GHz),  front keys operation of all the 3 SA's are same.

If you were at the other end and someone asked you the same question and gave you precisely this information. Would you be able to help them?? or even understand what is it that they are trying to communicate about the perceived problem or the instrument itself??


Help us help you.


Please start explaining what is that you have done, what is the problem you are seeing, what have to done to identify the issue behind and where is it that you have hit a road block? - in crisp, concise, complete statements.


People are very helpful here. Any motivation to help you will vanish quickly if you are perceived to be another spammer or a person who is out to waste their time.

The above quote u mentioned was one my reply to Bud, actually this is the
 start of my explanation :

1.As the instrument is switched on , FREQ UNCAL is displayed which is a permanent fixture.
2.When i try  to calibrate using CAL OUT the result is  SIGNAL NOT FOUND & SRQ110.
3. The trace line is slow in movement , data entry response also appears to be slow.

I couldn,t find service manual for 8594 series , but tried using 8590 series one.

As per that manual either A7 analog pcb, A16 processor , counter lock , or YTO may be faulty but not able to zero-on by using this manual.

I observed the following:

1.on A7 analog interface board Q1 is getting warm
  but if  cable running to YTO removed from the PCB, heat is normal.

2. FREQ UNCAL disappears & trace line moves fast when Counterlock board flat cable is removed

[kenramesh]

Exactly what BravoV was trying to gently inform you. When there is no response to a thread, the forum etiquette is to "bump" the same thread or update the status or your efforts or information. Not to create a new thread. 


PS: Same with the responses, it is much much easier if you responded to all the points in one reply instead of staggering each quote and rebuttal answer in a separate post.

thanx krish , but as Iam new to this forum joined on April 16 , 2018 , I need guidance from All of You both related to forum & technical aspects.

[krish2487]

Let me put that in a more clear way.

Pictures - of the schematics in the service manual of the specific section, of the instrument you have, Teardown pics if needed, screen captures of the instrument while in operation.

If the service manual of your specific model was not available then why did you choose what you are using now for repair?

What was your troubleshooting mindset?? Why did you do and observe what you did?
What did you do in isolating the problem ? Where did you go from there?? Did you try tracing the signal path on the boards you mentioned??
Did you check all the voltages and waveforms on the test points?? Power supply voltages??

Why did you feel the need to check the temperature of "Q1" what is the bearing of that component on what you suspect is the fault?? Is it a part of the signal path??

If you do not explain your methodology in detail other than vague questions, others cannot help you!!
I hope you understand what you have to do to receive help?
This is not a free service help forum. And people most certainly cannot read your mind. If you are not absolutely clear in what help exactly you want, you will not receive much! 


TLDR; If you expect to be spoon fed with the solution to your problem with the equipment then spoon feed us here with all the details. Even If you deem them to be irrelevant.
 

[BravoV]

thanx krish , but as Iam new to this forum joined on April 16 , 2018 , I need guidance from All of You both related to forum & technical aspects.

No excuse being new, its called consideration, manner and diligent especially you're asking for help, its universal language everywhere in the world.

Just see your request below ..

Hello guys,

i need help desperately to repair my HP 8594A spectrum analyser. 

Pls help me .

Thanx u all.

Imagine in India, two persons that you never know in your life, approach you ...

1st person ask ..
"I need help desperately to repair my bicycle, Pls help me ...."
... thats it, he said nothing else

2nd one ask exactly this ...
I need help desperately to repair my bicycle, Pls help me .... it has flat tyre and I don't know what next ..."
... even this sounds abit weird as you just need to say or ask for help for an air pump to inflate, but still the 2nd one is way better than the 1st one that is so lazy even asking for help.


Now back to your 1st post, what are you expecting people to respond with that kind of lazy request asking for help ? And worst, you claimed your self know and familiar how to operate it. 

I almost responded you with sarcasm like this ...

"Have you push the power button ?" or ..

"Please make sure you've plug into the mains socket" ...

.... cause you deserved with that kind of harassment.

[kenramesh]

The below mentioned stuff  was my first request on this forum on April 17, 2018  with 172 views , 0 replies
https://www.eevblog.com/forum/repair/repairs-of-hp-8594a which is now (today) locked due to duplicate thread.

Everyday I used to edit my post to bring it on top becoz no replies were received & the topic was fading from page 1. I tried for 3 days , then made one more post ( present post  )

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repairs of HP 8594A spectrum analyser
« on: April 17, 2018, 07:13:49 pm »
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hello all ,
I have been facing problem with HP 8594A spectrum analyser.

1.As the instrument is switched on , FREQ UNCAL is displayed which is a permanent fixture.
2.When i try  to calibrate using CAL OUT the result is  SIGNAL NOT FOUND & SRQ110.
3. The trace line is slow in movement , data entry response also appears to be slow.

I couldn,t find service manual for 8594 series , but tried using 8590 series one.

As per that manual either A7 analog pcb, A16 processor , counter lock , or YTO may be faulty but not able to zero-on by using this manual.

I observed the following:

1.on A7 analog interface board Q1 is getting warm
  but if  cable running to YTO removed from the PCB, heat is normal.

2. FREQ UNCAL disappears & trace line moves fast when Counterlock board flat cable is removed

waiting for ur help  Pls suggest how do proceed.

Thanx in advance

Locked due to duplicate thread: https://www.eevblog.com/forum/repair/help-needed-to-repair-hp-spectrum-analyser/msg1494742/#msg1494742
« Last Edit: Today at 04:19:33 pm by gnif »  "


I did mention in detail the problems I was facing  in my first thread . I was considerate , but dint receive any reply.

In my new thread , even if my opening post was short , as soon I received reply I mentioned all the problems I was facing with the SA.
Iam not complaining or blaming but as you mentioned consideration , manner , deligence , I thought of mentioning it to u.

[kenramesh]

Let me put that in a more clear way.

Pictures - of the schematics in the service manual of the specific section, of the instrument you have, Teardown pics if needed, screen captures of the instrument while in operation.

If the service manual of your specific model was not available then why did you choose what you are using now for repair?

What was your troubleshooting mindset?? Why did you do and observe what you did?
What did you do in isolating the problem ? Where did you go from there?? Did you try tracing the signal path on the boards you mentioned??
Did you check all the voltages and waveforms on the test points?? Power supply voltages??

Why did you feel the need to check the temperature of "Q1" what is the bearing of that component on what you suspect is the fault?? Is it a part of the signal path??

If you do not explain your methodology in detail other than vague questions, others cannot help you!!
I hope you understand what you have to do to receive help?
This is not a free service help forum. And people most certainly cannot read your mind. If you are not absolutely clear in what help exactly you want, you will not receive much! 


TLDR; If you expect to be spoon fed with the solution to your problem with the equipment then spoon feed us here with all the details. Even If you deem them to be irrelevant.
 

(1) I checked power supply voltages , all are fine : +12v , +/- 15v, +5 V ( on processor board testpoints).
(2) We use this SA , the unit failed so trying to repair. We have one more SA HP 8590L which is 1.8GHz BW. We need 2.9 GHz.
(3)Service manual available is HP 8590 series with differs with HP 8594A but basic the same.
    As per the manual if FREQ UNCAL occurs either A7/A16/A15/A8 /A25(if board present in the unit ) might be faulty.
A7--Analog onterface
A16--Processor
A15--Motherboard
A8--Powersupply
A25--counterlock

as we dont have any spare boards to zero-on the problem I am trying to get help from here.

[SaabFAN]

You have run the internal self-test?

Just a shot in the dark: Was the SRAM-Battery / The Chip with the Calibration-Data ever changed? If the instrument loses these information, it may very well be that the coarse DAC for the YTO is putting out the wrong values so the PLL cannot lock anymore.

[hendorog]

That something connected to the YIG is getting warm is normal. That thing requires quite a bit of current to generate the magnetig fields.

YIG's normally have a heater.
Here is some info on driving one from a power supply, although not much use unless you have another way of measuring the output.

http://www.rollanet.org/~joeh/projects/Connecting_the_HP_5086-7023_YTO.pdf

[kenramesh]

You have run the internal self-test?

Just a shot in the dark: Was the SRAM-Battery / The Chip with the Calibration-Data ever changed? If the instrument loses these information, it may very well be that the coarse DAC for the YTO is putting out the wrong values so the PLL cannot lock anymore.

Iam gonna check the same & get back

thank you

[kenramesh]

That something connected to the YIG is getting warm is normal. That thing requires quite a bit of current to generate the magnetig fields.

YIG's normally have a heater.
Here is some info on driving one from a power supply, although not much use unless you have another way of measuring the output.

http://www.rollanet.org/~joeh/projects/Connecting_the_HP_5086-7023_YTO.pdf

going thru the info provided

thank you

[HighPrecision]

I have two preliminar service manuals for 8594A and 8595A, both are referenced to 8593A service manual as similar.

8594A:
https://www.dropbox.com/s/tcbbsknii8df9n3/8594A_Preliminary%20Service%20Manual.pdf?dl=0

8595A:
https://www.dropbox.com/s/e3gdwtknw44ndej/8595A_Preliminary%20Service%20Manual.pdf?dl=0

I'm unable to find a manual for 8593A, but found a complete manual for 8595A:
http://www.ko4bb.com/getsimple/index.php?id=download&file=HP_Agilent/HP_8595A_Service_Manual.pdf

Page 421 describes possible SW/HW causes of "FREQ UNCAL" message.

Starting here you find CLIP schematics:
http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=HP_Agilent/HP_8590_Spectrum_Analyzer/HP_8590_Clip