Re: Looking for power supply schematic of Agilent 83751A
After 6 hours troubleshooting, it is fixed. The reason is C35 short. 100uF/50V electrolytic capacitor. Here is what I traced the partial schematic of HP83751A power supply.? ?After C35 short, the PWM controller does not drive the MOSFETs.? Also checked the ESR of C1, which is too much, 2 ohm, it will soon fail, just replaced with a new one. Regards Lin.
On Saturday, February 19, 2022, 03:03:07 PM EST, inlinebeginner via groups.io <inlinebeginner@...> wrote:
Hello
? Does anyone know where I can find the power supply schematic of Agilent 83751A or B (Synthesized Sweeper, 2 - 20 GHz) ?? I downloaded the service guide, it only contains block diagram (very helpful), but no detailed schematic. The power supply stopped working, I need to repair it.
? Symptom:? Could not power on. Rear panel 2 LEDs all off. Internal standby LED is on. Short A3W2 Pin 16 to ground, no response.
Thanks
Lin
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HP8903B - THD measure on Phono RIAA preamplifier
Good morning everyone,
I recently bought an HP8903B audio analyzer, and I'm trying to test a RIAA phono preamp with it. I was able to check the RIAA response curve, but I didn't get decent results as far as the distortion measure is concerned.
I was thinking of inserting a precise reverse RIAA between the HP8093B output and the phono preamplifier input so that the HP8903B sees it as a line preamp and I can have a correct distortion measurement.
What do you think ?
Is there any better method?
Thanks for any advice / suggestion.
-- Cheers
??? Attilio
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Thanks! I was having a devil of a job trying to find those test points! I never had such a problem with the old loose-leaf binder type manuals.
I'd expected to see *some* ripple present across the filter caps, but 10% was a surprise I must say.
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Typo correction: the 12V rail is at A17TP6 (not A17TP4).
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Re: Good Progress on 8753E EEPROM - Need More Guidance
Hi Marcus:
Yes, I am going to pull the second EEPROM Today, and read it. That one does have OPT6, so maybe I can correlate what address I need to focus on. Another member of the group sent me a .bin that seems to suggest F7 F7 F7 as opposed to 01 01 01 might have been the second issue I am having. I only chose 01, because the address where OPT11 resides had 01 to activate the option. Let me see what I can learn from the EEPROM which has OPT6 invoked.
Hopefully something I can make a better understanding of what is going on once I have the second EEPROM read.
Thanks,?
Rich?
On Sunday, February 20, 2022, 04:36:59 AM EST, Marcus Gustafsson <mankan@...> wrote:
Rich, the reason for not getting the results you expect is that you are assuming that 8753D and 8753E has the same EEPROM layout. I recommend using the 8753D EEPROM layout as inspiration only and that you focus on analyzing the differences in the two EEPROMs you have, to find what bits to flip. Best regards Marcus
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As Tom said, this is exactly as it should be!
You should not care much about ripple that you see before the outputs of the different regulators on the A8, A17 and A18 boards. However, you should see negligible ripple (less than 3mVp-p is typical) on the following test points:
A8TP1 (+22V rail)
A17TP4 (+20V rail)
A17TP4 (+12V rail)
A17TP2 (+5.2V rail)
A18TP5 (-5.2V rail)
A18TP1 (-40V rail)
A18TP4 (-10V rail)
When you test for ripple, stop the instrument from sweeping (e.g., by selecting "single sweep") as sweeping? introduces slight noise into some rails that is sometimes confused with ripple.
See the "Performance Tests and Adjustments Manual" section titled "Low-Voltage Power Supply Adjustments" subsection "RF Section" for the voltage tolerances for each supply rail and the locations of the different test points mentioned above (BTW, I could never find in the manuals a specification of the allowed ripples) .
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Re: HP-8753E R Channel Output Free Running
This one was solved this morning. It did not like the CAL data from the 8753E which this board has come from. I loaded the constants which came from the host machine and this seemed to resolve it.?
On Saturday, February 19, 2022, 11:34:35 PM EST, Rich Miller via groups.io <av8torrich@...> wrote:
Despite my initial success making progress on the EEPROM, it appears Murphy has struck. I started getting an error regarding the R Channel Input on my 8753E. When I plugged the R Channel output into my Spectrum Analyzer, I get the result as seen in the picture attached. Looks to me like something is free running at 2.55GHz or so.
I have the VNA in zero span at a frequency of 50MHz. As you will note the signal seems to be jumping all over based on my Max Hold capture. The primary signal is consistently at or around 2.5GHz (close to it), but makes massive excursions.??
I suppose not good deed goes unpunished! Time to start chasing this down.
Rich?
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Re: Mixing 'n' matching S parameter test sets
?I have to go against the the nay-sayers.
There is no reason why you cannot use the 85046A with the 8754A. The only issue is controlling it. Fortunatly the interface is really simple. You need 4 bits of data and a strobe (trigger) plus a 22V unregulated supply. Three of the bits are for the attenuator (10, 20, 40dB) and one for the RF relay / switch. So you need as a minimum 4 toggle switches and a push button switch plus DC power supply. If you want to get fancy a 3 bit Binary / BCD switch for the attenuator will allow direct selection.? You just set the switches and push the button.
A quick look at the manual and schematic should make it clear.
Robert G8RPI.
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A sawtooth ripple on the unregulated DC is exactly what you should
see -- the cap rapidly charges up when the rectifier forward biases,
but slowly discharges once the rectifier goes into reverse bias.
If the regulator always regulates, then that ripple is benign. That
is, ripple on the unregulated DC is to be expected. If ripple
doesn't show up on the output, then the regulator is doing its job.
--Cheers,
Tom
--
Prof. Thomas H. Lee
Allen Ctr., Rm. 205
350 Jane Stanford Way
Stanford University
Stanford, CA 94305-4070
On 2/20/2022 04:48, Jinxie wrote:
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Hi all,
This relates specifically to the 8566B but is no doubt relevant to
all analysers with linear power supplies.
My 8566B has been suffering from the infamous YTO ulock error and
it was suggested on some Youtube clip that it would be a good idea
to scope the power rails. To cut a long story short, I was seeing
ripple further down the line (in the direction away from the main
PSU section) so I decided to go back to the start and scope the
main storage electrolytics (you know, the big, beefy ones to use
the correct terminology). Anyway, they *all* have ripple on them
and it's more than I would expect, at around 10% of the DC
voltage. So for example on 12VDC I'm seeing just over a volt P-P
of ripple. Furthermore, it's not sine waveform either, but
saw-tooth! I did check these caps for ESR and capacitance some
time ago with my Peak ESR meter and they all came out OK as I
recall. So I'm not sure what to check next. Any suggestions? I've
got all the service manuals and whatnot on DVD but find it much
harder to follow what wiring goes to where without a proper
hard-copy book type manual to flick through. :(
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Hi all,
This relates specifically to the 8566B but is no doubt relevant to all analysers with linear power supplies.
My 8566B has been suffering from the infamous YTO ulock error and it was suggested on some Youtube clip that it would be a good idea to scope the power rails. To cut a long story short, I was seeing ripple further down the line (in the direction away from the main PSU section) so I decided to go back to the start and scope the main storage electrolytics (you know, the big, beefy ones to use the correct terminology). Anyway, they *all* have ripple on them and it's more than I would expect, at around 10% of the DC voltage. So for example on 12VDC I'm seeing just over a volt P-P of ripple. Furthermore, it's not sine waveform either, but saw-tooth! I did check these caps for ESR and capacitance some time ago with my Peak ESR meter and they all came out OK as I recall. So I'm not sure what to check next. Any suggestions? I've got all the service manuals and whatnot on DVD but find it much harder to follow what wiring goes to where without a proper hard-copy book type manual to flick through. :(
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Re: Mixing 'n' matching S parameter test sets
The antiquity of the 8754A is part of the appeal, though! It's closer to the fundamentals of network analysis and there are no abstraction levels between the operator and the machine as is the case with more modern kit. I should mention I'm heavily into vintage test equipment which has a certain appeal for my personally, though it wouldn't suit everyone of course.
I bought the 8754A and the storage normaliser for it many years ago but since I never had the S parameter test set for it, I never did much with it. More recently I acquired an 8753 series VNA together with the matching S parameter test set and it just occurred to me that I could fully check out the old VNA by hooking it up to the newer test set if that was possible without causing damage to either component. So there's a bit of background for you. Unfortunately from what's been posted to this thread it appears they just won't work together, however. :(
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The 1820-2131 is used in the 5315A/B and 5316A Universal Counters. I'm not aware if it being used in any other instrument.
Also known as the MRC, "Multiple Register Counter" and described with some detail in the January 1979 issue of HPJournal.
Pure unobtainum, I'm afraid ...
Joel Setton
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Re: Good Progress on 8753E EEPROM - Need More Guidance
Rich,
the reason for not getting the results you expect is that you are assuming that 8753D and 8753E has the same EEPROM layout.
I recommend using the 8753D EEPROM layout as inspiration only and that you focus on analyzing the differences in the two EEPROMs you have, to find what bits to flip.
Best regards
Marcus
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Re: HP8903B - Plotting from HP-IB
Hi Tony
Please contact me off group
Hardy
?
?
Thanks Dave, for the info - I'll have to take a look into
VISA for the ProLogix - I moved from a Prologix to an 82357 and ended up with
an NI GPIB-ENET/1000 - It'd be good to have the possibility of using the
Prologix as well.
Attilio - When you get the Keysight IO Libraries Suite installed you may still
need to configure the instrument to use address 14 or modify the settings used
by Pete's software - In VEE there is a thing called Instrument Manager and you
can do that - Pete has information on his website about it.
Good luck with it.
TonyG
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HP-8753E R Channel Output Free Running
Despite my initial success making progress on the EEPROM, it appears Murphy has struck. I started getting an error regarding the R Channel Input on my 8753E. When I plugged the R Channel output into my Spectrum Analyzer, I get the result as seen in the picture attached. Looks to me like something is free running at 2.55GHz or so.
I have the VNA in zero span at a frequency of 50MHz. As you will note the signal seems to be jumping all over based on my Max Hold capture. The primary signal is consistently at or around 2.5GHz (close to it), but makes massive excursions.??
I suppose not good deed goes unpunished! Time to start chasing this down.
Rich?
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Good Progress on 8753E EEPROM - Need More Guidance
All:
I made some excellent progress on my 8753E today. From the spare A9 CPU Board, I was able to read the XICOR EEPROM. This yielded the information I had been looking for. Since this is a spare A9 Board, and I have an image of U402 I decided to use the following data to write some changes to the EEPROM:
The A9 CPU board which has become my spare came from a HP-8753E that did not have OPT6 but did have OPT11. My 8753E, which I has had OPT06, and I am trying to add OPT10 and OPT2. As an experiment I did the following to the spare A9 CPU Board U402 Binary File:
- Address 0x00 - 0x02: 01 01 01 - This was changed from 00 00 00, these are the first three bits before the serial number.
- Address 0xBC 00 - This was changed from 01 which invoked OPT11, which my VNA cannot use as it's only a two port instrument.?
The result of the changes above gives a result that I did not expect. It did remove OPT 11. It added, OPT10 (Posts on Instruments Display next to serial number.), but there is no OPT6 (6GHz) or OPT2 (Harmonic).?
My understanding is all 8753E's have the ability to be upgraded to OPT6 with existing hardware and the bits at address 0x00 - 0x02 should have activated OPT10, OPT6, OPT2. I still find this to be great progress and am encouraged by the result, as it means I am going in the right direction.?
I wonder if someone who has played with these 8753E's can comment on these results, and possibly tell me what additional bits must be thrown to activate OPT6 and OPT2.
Thanks!
Rich?
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It might help if one knew what instrument the ic is used in.
Sam Reaves
ARS W3OHM
Owner / Moderator of: LeCroy Owners Group on Groups.io
Sencore Owners Group on Groups.io Sprint Layout Group on Groups.io?? Pulsonix EDA Group on Groups.io
LPKF Owners Group on Groups.io
Electronics and Mechanical Hardware Design Engineering Manager
Staff Scientist Andritz Rolls Global Research Center (RETIRED)
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Hi Bruce
You are probably correct from memory it was the first HP plug in I was repairing and it was in the trigger CCT? if the fault was there from manufacture
The scope would have had a bad history as not having a good sweep trigger it was? a Paine to find the fault and I couldn't find? a replacement so just turned the original around and all was OK
Regards Paul
?
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-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Bruce
Sent: 20 February 2022 00:32
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] HP detector
Another possibility is that the diode was mismarked, but correctly positioned in an auto-insertion pack.? Automation would ignore the mismarking, and final inspection could miss it.
Cheers!
Bruce
Quoting tmillermdems <tmiller11147@...>:
> /I have seen mismarked diodes as well as equipment that was never
> tested (or powered up). It's rare but it happens./
>
> /Regards/
>
> On 2/19/2022 5:14 PM, Paul Bicknell wrote:
>>
>> Hi just a line hear hopefully without stealing the thread when
>> repairing a HP 180 scope plug in one diode was reverse polarity to
>> its marking compared to others in the same plug in
>>
>> Reversing the diode fixed the problem
>>
>> My question is how did this change polarity as I assume it was
>> correct at manufacture of the plug in? otherwise the plugin should
>> have failed end of line testing
>>
>> Regards Paul
>>
>> *From:*[email protected]
>> [mailto:[email protected]] *On Behalf Of *Dave
>> Wright
>> *Sent:* 19 February 2022 15:13
>> *To:* [email protected]
>> *Subject:* Re: [HP-Agilent-Keysight-equipment] HP detector
>>
>> Tom,
>>
>> Thanks for the confirmation..!
>>
>> And, can you comment on if / how the whisker tip geometry might
>> affect characteristics..? I'm wondering if a 'blunt' tip at the
>> contact point might alter performance at high frequencies...
>>
>> _Dave KC6UPS
>>
>>
>
> --
> This email has been checked for viruses by Avast antivirus software.
>
>
>
>
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Another possibility is that the diode was mismarked, but correctly positioned in an auto-insertion pack. Automation would ignore the mismarking, and final inspection could miss it.
Cheers!
Bruce
Quoting tmillermdems <tmiller11147@...>:
toggle quoted message
Show quoted text
/I have seen mismarked diodes as well as equipment that was never tested (or powered up). It's rare but it happens./
/Regards/
On 2/19/2022 5:14 PM, Paul Bicknell wrote:
Hi just a line hear hopefully without stealing the thread when repairing a HP 180 scope plug in one diode was reverse polarity to its marking compared to others in the same plug in
Reversing the diode fixed the problem
My question is how did this change polarity as I assume it was correct at manufacture of the plug in? otherwise the plugin should have failed end of line testing
Regards Paul
*From:*[email protected] [mailto:[email protected]] *On Behalf Of *Dave Wright
*Sent:* 19 February 2022 15:13
*To:* [email protected]
*Subject:* Re: [HP-Agilent-Keysight-equipment] HP detector
Tom,
Thanks for the confirmation..!
And, can you comment on if / how the whisker tip geometry might affect characteristics..? I'm wondering if a 'blunt' tip at the contact point might alter performance at high frequencies...
_Dave KC6UPS
--
This email has been checked for viruses by Avast antivirus software.
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Re: Mixing 'n' matching S parameter test sets
John Lyles¡ ? ¡°The 85046A was made for the 8753 series of VNAs and has switching of signal direction built in, as well as four port capability.¡± ? Please explain the 4-port capability. I was not aware it had that and would like to know more. ? Thanks. ?
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From: [email protected] <[email protected]> On Behalf Of John Lyles
Sent: Saturday, February 19, 2022 4:07 PM
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Mixing 'n' matching S parameter test sets? Those are completely different generation VNAs. The 8754A is strickly a manual VNA in that if you want calibration of cables and fixtures you will need to have the storage normalizer box or you can use grease pencils on an overlay on the screen! The 85046A was made for the 8753 series of VNAs and has switching of signal direction built in, as well as four port capability. Your 8754A doesn't have the drivers to do that. Just because it has the type N connectors for the RF ports, it doesn't have the smarts to drive the switches. When 8754A was developed, it was impossible to predict what the future microprocessor-based VNA would be. The 85044A or B transmission/reflection test set will work with it as it has no switching and has only an attenuator with a knob. They can be found relatively cheap. I had a couple of them, sold one and now I use the other with my Rigol RSA-3000 series spectrum analyzer/tracking generator as a SNA (scalar network analyzer) to 3 GHz.
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Attilio
Jinxie
Sam Reaves
Paul Bicknell