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Re: 3577A multiple problems - update

 

The unlock is due to the A7 module.? The problem seems to be in the 300-500 MHz oscillator.? Using the W1 jumper to set it to the low and high frequencies is supposed to give a 300 MHz total range (say, 250-550 MHz) but I get 363 to 529 MHz.? So something's wrong in the oscillator circuit that prevents it from going to the lowest frequencies.? As a test, I tried to set the analyzer to 190 MHz where I would expect the synthesizer to put out 490.250 MHz, and it did, however after a short time it went unlocked again and went up to 529 MHz.? So something additional seems to be wrong.? I checked the internal +12 volt supplies on that board and they are all in spec.? Yikes, might be a hard to find varactor diode.
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I still get a CPU invalid instruction error after a while.? I think I'm going to take a break from the VCO problems and see what I can find in the CPU.? Perhaps a bad ROM which is temperature sensitive?
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Anyone have similar problems with this instrument?
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I can't believe how messed up it is.
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Peter
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Re: 3577A multiple problems

 

¿ªÔÆÌåÓý

Update:

The +15 issue turned out to be a bad adjustment pot. Replaced and it looks good now.?

Beginning to lose faith in old HP gear.?

The oven oscillator first had no output. Dirty power connector to board. Now, after it warms up, I can¡¯t get the adjustment to bring it to frequency. Best is 10 Hz low. ?I can use with an external reference, but it looks like it needs to be replaced.?

I get A5, A6 or A7 unlock error message on internal or external reference. That¡¯s next?

But I am also getting intermittent bus errors and illegal instruction errors. Wow.?

Not sure what ISN¡¯T wrong with this thing! ?And it was working fine before. Yeah I reseated the boards and used DeOxit Gold on the connectors. Power supply seems solid and I didn¡¯t see anything on a scope when getting the CPU errors.?

Peter

On Dec 14, 2024, at 1:24?PM, Peter Gottlieb via groups.io <hpnpilot@...> wrote:

?
?Thanks.?

I¡¯m pretty confident two RAM chips are bad as when I move them the reported fault moves with them.?

I just discovered that I cannot adjust the +15 supply and it is at the high end of acceptable at 15.5 volts. Also there is excessive ripple. Pretty sure it is the LM338K so I ordered a replacement. Also if you watch long enough you see the voltage jump around. The -15 supply is adjustable and very close. I am not confident I have found all power supply issues. Sometimes it takes a few minutes of watching to see something going wonky so it is a slow process.?

I am also seeing oscillator unlock messages as well as bus errors but won¡¯t go after those until I am sure the power supply is perfect.?

Peter

On Dec 14, 2024, at 12:53?PM, dan.meeks222@... via groups.io <dan.meeks222@...> wrote:

?
Peter -
No help here, I just wanted to give you a data point: I have had one of these for a long time, and it sits unused for weeks or months between uses, and I have not had any issues.?
If there is something I can do to help you troubleshoot, let me know. I probably don't want to dig deep into the guts or solder anything but if there is something less invasive that might help I am happy to do that.
Dan
Re: 3577A multiple problems

 

¿ªÔÆÌåÓý

?Thanks.?

I¡¯m pretty confident two RAM chips are bad as when I move them the reported fault moves with them.?

I just discovered that I cannot adjust the +15 supply and it is at the high end of acceptable at 15.5 volts. Also there is excessive ripple. Pretty sure it is the LM338K so I ordered a replacement. Also if you watch long enough you see the voltage jump around. The -15 supply is adjustable and very close. I am not confident I have found all power supply issues. Sometimes it takes a few minutes of watching to see something going wonky so it is a slow process.?

I am also seeing oscillator unlock messages as well as bus errors but won¡¯t go after those until I am sure the power supply is perfect.?

Peter

On Dec 14, 2024, at 12:53?PM, dan.meeks222@... via groups.io <dan.meeks222@...> wrote:

?
Peter -
No help here, I just wanted to give you a data point: I have had one of these for a long time, and it sits unused for weeks or months between uses, and I have not had any issues.?
If there is something I can do to help you troubleshoot, let me know. I probably don't want to dig deep into the guts or solder anything but if there is something less invasive that might help I am happy to do that.
Dan
Re: 3577A multiple problems

 

Peter -
No help here, I just wanted to give you a data point: I have had one of these for a long time, and it sits unused for weeks or months between uses, and I have not had any issues.?
If there is something I can do to help you troubleshoot, let me know. I probably don't want to dig deep into the guts or solder anything but if there is something less invasive that might help I am happy to do that.
Dan
Re: 3577A multiple problems

 

The connectors and PC B edge connectors are first suspect In these 1970s..1980s HP meters.

Opening up and removing, reseating all the PC Cards , May fix it.

Then see the connectors especially any multi pin ribbon, etc.

Second suspect is any switches and pots that are scratchy.

Jon
Re: HP8594E repair with "ADC-2V FAILL"

 

What a coincidence!
I have just switched on my trusted HP8593E and it shows exactly the same problem.
It had been running without problems for the last 10 years in my lab.
?
Many thanks for the detailled description of your work, Vincent.
I'll see if it is the same problem. A good starting point anyway...
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First, I have to fix my Tek scope that died earlier this week. Not a good week. :-(
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Tom
3577A multiple problems

 

Today I fired up my 3577A to begin to do some tests.? It has been sitting in my lab, fully environmentally controlled, for several years unpowered.? It was working perfectly when it was put away.
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Immediately I got a trace memory failure, shows as banks 2 and 6.
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I ran further tests and got failures:
Log sweep signal level test
Log sweep flatness test
Linear sweep signal level test
Linear sweep flatness test
Synthesizer and LO test
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So I checked the power supplies and reference, all look great.? Hmmm, what could be a common cause then?
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I started with the trace memory.? I put in a bunch of sockets and moved around chips.? Indeed two of the 2k x 8 Toshiba RAM chips appear to be bad as the failure follows them to whatever bank I plug them into.
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Anyone else just have these chips die while sitting around unused?
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As I need to order replacements I will have some time to probe around.? Apparently something else has failed just sitting around.
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Any thoughts as to where I should start?
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Re: HP 8593A Display repair

 

thank you for help.

picture added.


Am 13.12.2024 um 00:11 schrieb Yves Tardif via groups.io:

Hi,

When the Spectrum loses all its calibration constants, there is a chance that you will lose the synchronization of the display on the screen. You should try to do a "DEFAULT CAL DATA" and "CRT HORZ" for the display.

But do in order if you don't see the softkey menu:
PRESET
CAL
MORE (softkey #6)
CRT HORZ (softkey #5) and CRT VERT (softkey #4)
TURN KNOB TO TRY SYNCHRONIZE DISPLAY
------------------

PRESET
CAL
MORE (softkey #6)
MORE (softkey #6)
DEFAULT CAL DATA (softkey #3)


If it's possible, send us a picture of your screen.

Yves



-----Message d'origine-----
De : [email protected] <[email protected]> De la part de Martin M
Envoy¨¦ : 12 d¨¦cembre 2024 14:36
? : [email protected]
Objet : [HP-Agilent-Keysight-equipment] HP 8593A Display repair

I have a repair of HP8593A with the following problems:

The PSU was fail. now complete recapping, it works.

The lithium battery was rip and the memory empty. Now it have a fresh battery, but the shp have to learn what is in the memory.

The display is fail: I see only a part of the screen, like a zoom in, and vertical triple.
How I can find the problem? It will be in the monitor box, inside.


thank you.









8593a-display.jpg

HP8594E repair with "ADC-2V FAILL"

 

A friend sent me a failed HP8594E with the error message "ADC-2V FAILL" over the screen. I searched the network and most of the info tell me the power supply is failed. I opened the machine and saw the +15V LED is dark to say the power for +15V is abnormal.
1. disassemble the PSU and there is no obvious burn-out device found.?
2. Should I focus on the PSU or check other part of the machine ? I took the 2nd way to isolate the other boards.
3. By pull out the board over the shielding compartment one-by-one and check the PSU +15V LED, it still turn dark.
4. In the final, I pull out the analog interface board, then the PSU +15V LED turn light and the the HP8594E to boot properly.
5. After checking the resistance over the bypass capacitor with multimeter, the +15VF show a low impedance to ground(below 1 Ohm)
6. My first guess is the large electrolytic capacitor over +15VF. Check the CLIP manual, I remove C317(470uF, 25V). No luck, short-circuit keep over +15VF to ground
7. In the next day, borrow a thermal image camera from friend. Using a power supply to provide 0.5V over +15VF and ground, the current consumpion is over 500mA. In the same time to check
the board with thermal image camrea. Yes, the C19 is highlighted over the camrea. With visual inspect, there is nothing wrong with it.?
8. After remove C19, the short-circuit over +15VF and ground is disappeared. Replace C19 with a new one and assembly everything back. Now, the HP8594E is worked again
9. This SA is not to work for a long time and it seems need to further calibration to keep its accuracy.
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73 de bv3ue, Vincent
?

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Re: 8751A Input Overload

 

That's interesting that yours is the same. Yes I also found if I reduced the source power slightly everything was OK. I have the IF bandwidth set at auto rather than 4khz?
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I've not noticed this with the one we have at work. Next time I'm in I'll check the settings on it.?
Re: HP 8593A Display repair

 

Hi,

When the Spectrum loses all its calibration constants, there is a chance that you will lose the synchronization of the display on the screen. You should try to do a "DEFAULT CAL DATA" and "CRT HORZ" for the display.

But do in order if you don't see the softkey menu:
PRESET
CAL
MORE (softkey #6)
CRT HORZ (softkey #5) and CRT VERT (softkey #4)
TURN KNOB TO TRY SYNCHRONIZE DISPLAY
------------------

PRESET
CAL
MORE (softkey #6)
MORE (softkey #6)
DEFAULT CAL DATA (softkey #3)


If it's possible, send us a picture of your screen.

Yves

-----Message d'origine-----
De : [email protected] <[email protected]> De la part de Martin M
Envoy¨¦ : 12 d¨¦cembre 2024 14:36
? : [email protected]
Objet : [HP-Agilent-Keysight-equipment] HP 8593A Display repair

I have a repair of HP8593A with the following problems:

The PSU was fail. now complete recapping, it works.

The lithium battery was rip and the memory empty. Now it have a fresh battery, but the shp have to learn what is in the memory.

The display is fail: I see only a part of the screen, like a zoom in, and vertical triple.
How I can find the problem? It will be in the monitor box, inside.


thank you.
Re: 8751A Input Overload

 

¿ªÔÆÌåÓý

Same for me, starting at 5Hz at 0dBm, the message takes a few seconds and appears.

But if I put the signal at -1dBm, the message does not appear.

?

But I noticed at 0dBm, that if I put my filter at 4kHz, the message appears, but not for the other filters.

I have not done detailed tests, but I would say that everything is probably normal.

At 4kHz, there is a greater chance that the harmonic energy is added for the detectors... but for now, I have not analyzed anything, it is a hypothesis.

?

Yves

De?: [email protected] <[email protected]> De la part de vee-dub565 via groups.io
·¡²Ô±¹´Ç²â¨¦?: 12 d¨¦cembre 2024 17:08
??: [email protected]
Objet?: Re: [HP-Agilent-Keysight-equipment] 8751A Input Overload

?

Done a bit more investigation. I found that it seems to be the bottom end of the sweep that causes an issue. With the sweep set at 10Hz - 500MHz it will sit there quite happily indefinitely, and functions absolutely fine. With the sweep set at 5Hz - 500MHz then it doesn't take very long before I get the input overload error.?

?

I checked source power is set to 0dBm and the problem occurs across all 3 inputs.?

?

?

?

?
Re: 8751A Input Overload

 

Done a bit more investigation. I found that it seems to be the bottom end of the sweep that causes an issue. With the sweep set at 10Hz - 500MHz it will sit there quite happily indefinitely, and functions absolutely fine. With the sweep set at 5Hz - 500MHz then it doesn't take very long before I get the input overload error.?
?
I checked source power is set to 0dBm and the problem occurs across all 3 inputs.?
?
?
?
?
Re: 8751A Input Overload

 

¿ªÔÆÌåÓý

Hi,

?

If you press ENTRY OFF, does the message disappear and appear again?

?

I have an 8751A, and it works very well. If you connect Port#1 output directly to port R, by default, the RF output is at 0dBm, and at +5dBm it is the limit, there will be a POWER TRIP signal too strong with the Overload message if the signal is > +5dBm. Make sure you have 0dBm and that the attenuator (ATTEN button) is at 20dB which is the default value for ports A, B and R.

?

Great VNA!

?

Yves

?

De?: [email protected] <[email protected]> De la part de vee-dub565 via groups.io
·¡²Ô±¹´Ç²â¨¦?: 12 d¨¦cembre 2024 14:37
??: [email protected]
Objet?: [HP-Agilent-Keysight-equipment] 8751A Input Overload

?

I just acquired an 8751A 5Hz to 500MHz network analyser. We have one of these at work and I thought I get my own to use for personal stuff. So I've set it up for a basic through measurement with a cable from RF Out to R and it cals out ok, but then comes up with input overload error.?

Before I delve into the service manual just wondered if anyone on here had any thoughts. Maybe it's an adjustment somewhere needs tweaking ?

?

If it's genuinely faulty then I might just get rid of it again spares or repair. I already have an 8753C and 8510C?
8751A Input Overload

 

I just acquired an 8751A 5Hz to 500MHz network analyser. We have one of these at work and I thought I get my own to use for personal stuff. So I've set it up for a basic through measurement with a cable from RF Out to R and it cals out ok, but then comes up with input overload error.?

Before I delve into the service manual just wondered if anyone on here had any thoughts. Maybe it's an adjustment somewhere needs tweaking ?
?
If it's genuinely faulty then I might just get rid of it again spares or repair. I already have an 8753C and 8510C?
HP 8593A Display repair

 

I have a repair of HP8593A with the following problems:

The PSU was fail. now complete recapping, it works.

The lithium? battery was rip and the memory empty. Now it have a fresh battery, but the shp have to learn what is in the memory.

The display is fail:? I see only a part of the screen, like a zoom in, and vertical triple.
How I can find the problem? It will be in the monitor box, inside.


thank you.
Re: HP 8341B with HP8410B VNA

 

I agree with Chuck - easy to change.? But you could also tke a look at the sweep output with a scope to determine if it is st for 1V/GHz or .5V/GHz.
?
Cheers!
?
Bruce
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Re: HP8753E, 8753D, 8753ES 3.5" disk drive replacement reference information

 

Scott, thanks much for the info.? For my 8753ES can you or anyone else in this thread tell me if I want the reverse polarity cable (default) or the forward polarity cable for item No. 1?
?
BRgds....Frank
Re: HP8753E, 8753D, 8753ES 3.5" disk drive replacement reference information

 

Slight correction regarding Vladan's comment:
On the 8753ES and E, there is also a plastic filler part which is not part of the FD. The 8753D may be different.
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This is absolutely correct for the 8753ES, but not for the 8753E which has the same physically wider design as the 8753D.? The difference between the original drive on the D and the E is the button position and type for the eject mechanism.? As noted, the holder (metal exterior mounting hardware) for the ES is narrower and will not fit these new Gotek drives without modification, but this is not an issue for the 8753D and 8753E models.? The 8753E holder can be mounted in the 8753ES if you want to use one of these to mount a Gotek drive into an 8753ES without physically modifying the drive.
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Re: HP8753E, 8753D, 8753ES 3.5" disk drive replacement reference information

 

A lot of thanks for all that very useful compilation Vladan!
Renaud
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