HP8757A Display Problem (Scalar Network Analyzer)
Hi all,
I have a HP8757A scalar network analyzer with a display problem which has appeared after some 6 months of no use. It was previously working just fine, with a HP8350B sweep generator and the 10MHz - 20GHz plug-in.
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What happens is that on switch-on, it goes thru the self-test and then reverts to a display which seems to contain some correct information such as frequency span, key button names (at the right), and a 'noisy' scan waveform (as expected) - BUT the display refresh is very slow and is well off-centre - it is clearly cycling through the 4 'display channels sources' but it is nearly unreadable (certainly unusable).
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I have another 8757A which I use with another sweeper which works well, and by using this as a 'test reference' I can determine which buttons to the right of the screen to use to perform some tests. In this way, I have called up the test pattern display (SYSTEM -> MORE -> SERVICE -> DISPLAY -> TEST PATTERN) and this generates the wanted test pattern BUT this is also well off-centre and refreshed slowly.
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I have checked the error-code LEDs (removed the top cover of course) and they are all off (zero) after switch-on or after "PRESET" which indicates no error found, and also checked the +15V, -15V and +5V on the small power board with the fuses. The +105V rail there is also correct.
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This problem is independent of whether the 8350B sweeper is on or off, and if it is on the PRESET button initializes both the 8757 and the 8350 as it should. I have compared the problem unit with the working unit and the basic functionality would appear to be present. I am wondering if the battery on the CPU board (backing up some constants?) could be a reason, but I doubt it - I can replace this tomorrow if I think it might be.
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I know that the refresh frequency of the display will be lower with the more channels that are being scanned (A, B, C, R) but this does not appear to change the problem on the unit that I am dealing with.
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For what it's worth, I have a comprehensive workshop and lab at home and I am used to working with both microprocessor designs and (more so) with microwave / ATV designs. I have read the service manual and operating manual but with so many pages and different references I am not sure where I should be looking.
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Would anyone here have a good idea of where the problem could be?
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My sincere thanks in advance.
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Re: HP DC Power Supply modification
Hi Nick,
That is a computer power supply not really related to this test equipment group. Have a websearch adding "lithium charger" they are popular with people charging big lithiums and some of their forums may have info. There are a number of possibilites including a simple adjustment, resistor change, software controlled adjustment or putting two or three silcon diodes in series with the sense connection.
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Robert. G8RPI
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Re: Looking for service manual/schematic for early E3611A DC Power Supply
I have started a new folder and uploaded all I have??? New folder?? E 3610,1,2 A ? Paul ?
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From: [email protected] [mailto:[email protected]] On Behalf Of Philip Freidin via groups.io
Sent: 16 May 2025 17:18
To: [email protected]
Subject: Re: [HP-Agilent-Keysight-equipment] Looking for service manual/schematic for early E3611A DC Power Supply ? You didn't specify which version of the schematic you had. I have 5959-5304? Edition 6 , October 2007.? Is this earlier than what you have? The document does not have a detailed component list, and many transistors, diodes, and op-amps on the schematic have no part numbers. The schematic does not include the meter section.
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Re: Looking for service manual/schematic for early E3611A DC Power Supply
This seems to have the correct schematic and parts list...
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Re: Looking for service manual/schematic for early E3611A DC Power Supply
You didn't specify which version of the schematic you had.
I have 5959-5304? Edition 6 , October 2007.? Is this earlier than what you have?
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The document does not have a detailed component list, and many transistors,
diodes, and op-amps on the schematic have no part numbers. The schematic
does not include the meter section.
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Cheers,
Philip
?
?
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I have checked the A3A8 board as indicated in the service manual and the results seem ok. The first photo shows the result with the "A" band selected. The second photo with the high band (Instrument preset) selected. Unfortunately I do not get the noise intervals on the high band, but only a continuous screen, as in the low band. Also I can no longer see any signal connected to the input, not even in the low band!  
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5334A replacement capacitor
I need a replacement or substitute for A1C19 (0180-2991), Sprague 67D398H020JL5A.? Mine let go in spectacular fashion, magic smoke, magic goo, pungent atmosphere.
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Thanks
--
Joe White
KW4YW
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HP DC Power Supply modification
? Hi to all, I am looking for a modification for the following PSU to ioncrease the voltage to 13.8V , any ideas? ? HP DPS-1400CB A PWS 1400W HSTNS-PD43 754383-001 DL360 G9 DL380 G9 LFF ? Thank you all ? Nick SV1VS
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Re: Question: Is there a correct* way to get an HP T141/855X Spectrum Analyzer to sweep logarithmically? (* as in: HP provided specific instructions/equipment for this)
Hi all,
I have a Tek 5L4N plugin for the 5000-series scope frames which was designed to be a log audio spectrum analyzer.? it will sweep log from 20 Hz to 25 kHz, linear from 100 Hz to 100 kHz with a tracking generator.
If anyone is interested in purchasing it I'd be interested...
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Cheers,
Howard Hoyt
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Re: Question: Is there a correct* way to get an HP T141/855X Spectrum Analyzer to sweep logarithmically? (* as in: HP provided specific instructions/equipment for this)
AFAIK the 141/855X system never had any log frequency sweep capability. It was a lot back then just to get linear and sometimes frequency-stabilized operation. More modern SA gear had more possibilities, but even then, I think log frequency sweeps were not common in RF/microwave gear. In other gear of the era, possibly in audio yes, but RF no, I think. OTOH, some low frequency function generators had log sweeps back them, so you could use them for the source, and use external sweep horizontal input for the analyzer display.
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Any gear that can take external frequency control input could conceivably be set up for log operation, but I don't think this was a common application since you'd need specific or custom external equipment to run it.
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One thing I think I recall from back then, that could do log frequency sweeps is the Tek 7L5 with a particular tracking generator/display option for that purpose. It counts as an audio/baseband SA.
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Ed
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Re: HP3582a problem no chanel 2
I had a similar problem with my 3582A: both channels showed OVERLOAD and no response. The solution was incredibly simple, some buttons on the front panel were bad (I suspected it might be the buttons near the INPUT/TRIGGER area) After a thorough cleaning of the panel, everything was back to normal.
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Looking for service manual/schematic for early E3611A DC Power Supply
Hi,
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I'm currently repairing an early HP branded model E3611A DC Power Supply to give to a friend, but the schematic from the usual online sources is for later models that differ in some parts (notably around the area I am trying to repair....)
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Does anyone have a copy of the service manual for early HP units they can share? I just need the schematic and parts listing in particular.
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Thanks!
Jared
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Re: ftp.agilent.com tar-file on archive.org
On Thu, 15 May 2025, Wolfgang Schraml via groups.io wrote: I've just downloaded the entire thing. No problems encountered. Thanks. I'll give that a try.
Wolfgang
========================================
On Thu, May 15, 2025 at 01:05 PM, Razvan Popescu wrote:
I download the whole archive a few years ago. I also had issues with the
download at that time but it was easy to resume the download because I
started it using "wget".
If you don't have a Linux box you can use the wget for Windows in a
Command Prompt window.
You can download from here the latest wget binary for Windows.
Use the following command:
wget -c
Best regards,
Razvan
On 15/05/2025 19:25, Wolfgang Schraml via groups.io wrote:
The Internet Archive has what appears to be a snapshot of
ftp.agilent.com from 2014. Link is
ftp.agilent.com < >.
The file is rather large (317GB) and an attempt to download failed after
approximately 220GB. I don't want to blow my monthly data plan and thus
decided to wait a little before attempting it again.
The Internet Archive allows the download of individual files from the
tar-ball, but I'd rather have a replica of the whole site to browse and
explore locally.
Has anyone successfully downloaded this tar file? Don't want to waste
time and bandwidth if the file is known to have issues.
Thank you,
Wolfgang
KI7PFX
--- * * KSI@home KOI8 Net < > The impossible we do immediately. * * Las Vegas NV, USA < > Miracles require 24-hour notice. * *
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Re: HP3582a problem no chanel 2
I also vaguely recall that there is a front panel screw driver overload adjust pot for each channel. Do check the OP/Serv manual for the front panel controls, setup, and calibration (adjustment).
Don Bitters
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Re: HP3582a problem no chanel 2
I am no expert on the 3582A, but check the motherboard sockets, the brd connectors any cabling to the input cards, and the circuit that comes after the input card, and the input control circuitry. I suspect you are seeing a DC level somewhere on the input circuitry after the input card that should not be there.
Don Bitters
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IIRC II is probably found in the IF A3 section, the video processor or detector.
Do you have a problem? What are your symptoms? If you are asking after the video digital sweep vs. the analog sweep, then look @ A3A8 brd and the EOS (End Of Sweep) sweep circuitry.
Don Bitters
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Re: ftp.agilent.com tar-file on archive.org
Thanks. I'll give that a try.
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Wolfgang
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========================================
?
On Thu, May 15, 2025 at 01:05 PM, Razvan Popescu wrote:
I download the whole archive a few years ago. I also had issues with the
download at that time but it was easy to resume the download because I
started it using "wget".
If you don't have a Linux box you can use the wget for Windows in a
Command Prompt window.
You can download from here the latest wget binary for Windows.
Use the following command:
wget -c
Best regards,
Razvan
On 15/05/2025 19:25, Wolfgang Schraml via groups.io wrote:
The Internet Archive has what appears to be a snapshot of
ftp.agilent.com from 2014. Link is
ftp.agilent.com <>.
The file is rather large (317GB) and an attempt to download failed after
approximately 220GB. I don't want to blow my monthly data plan and thus
decided to wait a little before attempting it again.
The Internet Archive allows the download of individual files from the
tar-ball, but I'd rather have a replica of the whole site to browse and
explore locally.
Has anyone successfully downloaded this tar file? Don't want to waste
time and bandwidth if the file is known to have issues.
Thank you,
Wolfgang
KI7PFX
?
?
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Question: Is there a correct* way to get an HP T141/855X Spectrum Analyzer to sweep logarithmically? (* as in: HP provided specific instructions/equipment for this)
(Bear with me, I¡¯m still learning how to use this platform)
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I¡¯m primarily interested in obtaining logarithmic sweeps/bode plots while using my 8556A audio frequency plugin and 8570A Storage Normalizer specifically for audio amp, loudspeaker, and crossover characterizations. Its native linear sweep/plotting makes it incredibly difficult to distinguish things at the low end of the frequency range; effectively prohibiting one from gathering useful data from a single 20Hz - 20KHz pass (I instead have to break up the single measurement into multiple, across smaller ranges¡ a very inconvenient endeavor).
Did HP ever publish any sort of instructions or app notes that address this? Did they produce any accessories/equipment specific for this?
?
I understand there were logarithmic converters available for XY plotters, but I¡¯ve yet to get any confirmation as to whether or not they would be best applicable to my specific needs, and/or how they would work in conjunction with the 8570 normalizer.
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Thoughts? Recommendations?
Thanks-
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Re: Twelve(+/-) bins of original HP/Agilent manuals free for pickup in San Diego
I'm resurrecting this thread as I've taken a chunk of these manuals at that time with the intention of figuring a way to scan them or make them available some other way. In the meantime, my storage capabilities have (just) diminished,?and I'm not sure when I'd be able to do?anything with these. I'm looking for another custodian in the LA metro area.
Anyone willing to take these? We're talking about four or so boxes 21"x16"x15".?
Greetings, Stan,
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Would you have any power supply-related documentation?
I'm in town.
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Thanks.
Sam
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Re: ftp.agilent.com tar-file on archive.org
I'm not sure, but the older versions are much smaller in size at maybe 100Mb.
On the wayback machine, all the older 78xxA downloads show up as access forbidden.
It is still possible to get the main 7800A SW but all the instrument specific programs (eg for PSA, ESA, PSG etc) report as access forbidden.
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I'm not sure what this means. I know that it wasn't always like this, because I can remember downloading some of them maybe 7 years back on the wayback machine and I was pleased that this was possible. However, when I look at the same archive today (same archive date) they are all causing an access forbidden message. None of them can be downloaded today so something has changed.
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--
Regards
Jeremy
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Trevor Gale
Paul Bicknell
Harold Foster
Philip Freidin
Jared Cabot
Sergey Kubushyn