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Re: HP8903B - THD measure on Phono RIAA preamplifier

 

Attilio,
What distortion values did you get? Also, what were the values you expected (and what is the preamp)? Is the level you are using for this testing appropriate for an RIAA preamp??

If indeed too far off, I'd recommend you look into possible sources of noise (such as improper?grounding), as the 8903 will return THD+N. For pure THD readings, I recommend you consider using an audio interface + something like ARTA. You can typically use the "monitor" output of the distortion analyzer to get a conveniently normalized level which would protect your interface and get the best of all worlds.?

Radu.?

On Sun, Feb 20, 2022 at 5:46 AM Attilio <a.alovisetti@...> wrote:
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

Re: Looking for power supply schematic of Agilent 83751A

 

On 2/20/22 01:28, Lincheng Xiu via groups.io wrote:
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.
Wow, I see electrolytic capacitors like that dry out and lose capacitance all the time, but I don't think I've ever seen one shorted. Nice troubleshooting!

-Dave

--
Dave McGuire, AK4HZ
New Kensington, PA
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.

Inline image


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

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
Re: Storage Cap Ripple

 

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.
Re: Storage Cap Ripple

 

Typo correction: the 12V rail is at A17TP6 (not A17TP4).
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

Re: Storage Cap Ripple

 

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) .
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?
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.
Re: Storage Cap Ripple

 

¿ªÔÆÌåÓý

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:

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. :(

Storage Cap Ripple

 

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. :(
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. :(
Re: HP ic needed

 

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
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
Re: HP8903B - Plotting from HP-IB

 

¿ªÔÆÌåÓý

Hi Tony

Please contact me off group

Hardy

?

Fra: [email protected] [mailto:[email protected]] P? vegne af Tony Goodhew
Sendt: 18. februar 2022 15:52
Til: [email protected]
Emne: Re: [HP-Agilent-Keysight-equipment] HP8903B - Plotting from HP-IB

?

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


Virusfri.

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?

tek00002.png

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?
Re: HP ic needed

 

It might help if one knew what instrument the ic is used in.

Sam Reaves
ARS W3OHM
Owner / Moderator of:
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Electronics and Mechanical Hardware Design Engineering Manager
Staff Scientist Andritz Rolls Global Research Center (RETIRED)
Re: HP detector

 

¿ªÔÆÌåÓý

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

?

-----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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