hybridfree/eevblog-posts huggingface dataset:
HP 7550A Plotter - Auto-feeder and paper eject issue - Page 1
Forum section: electronics / repair

author: Tony_G
author_rank: Super Contributor
timestamp: August 12, 2023, 02:58:08 pm
content: Hey All,Just thought I'd post this here for anyone that went looking for answers on it.I acquired a HP 7550A that was suffering from the auto-feeder failing to load paper. Opening the unit up didn't show anything obviously wrong and using the internal test routine (power the unit on while holding down the ENTER and 2 keys) showed that the photosensors were working as expected.Digging around I found a page on the HP support website that talked about a different problem, the paper immediately ejecting after manual loading. The problem they claimed was that the sensors needed calibration and the suggested solution was to run the diagnostics routine.This had no impact on my problem because I had already run it and nothing had changed but it led me to think about running the internal X-Y Motor Gain Calibration. The service manual says to run this after certain repairs so I thought, "why not give it a try" seeing that I might need to replace the motors anyway.You run this by powering on the until while holding down the ENTER and 4 keys.Well after a bit of motor back and forth, I tried the auto-feeder and it has now started working.If you're suffering the same problem then this might be a helpful step in addressing the issue.TonyG
HP 8000 elite 4 beeps problem (component level trubleshooting) - Page 1
Forum section: electronics / repair

author: FileNotFound__
author_rank: Contributor
timestamp: May 18, 2022, 05:01:14 pm
content: I have a Hp compaq 8000 elite ssf system that was given to me.I do not know the history of the computer but i really want to get it running.When the system poweres on, the front fan spins up to 100% and stops, folloved by 4 beeps and a flashing red light. (The power supply fan never spins up)After a while of investigating, i concluded that it is eather the motherboard or the power supply.I tested the power supply by manually switching it on and loading it with a few power resistors (7A load on a 12V rail) It performed fine exept power good signal, from the expirience i know that it is usually 5V but on this one I get only 2V, alltought it might just be a poprietery design. I tried feeding 5V and even disconnecting the power good wire, no difference. I tried disconnecting remote vire, got no fan spin and the same 4 beeps.When it comes to the motherboard, I tried different RAM, I didn't have a compatible CPU but when I start it with no CPU i get 3 beeps and no attempt of startup.Monitoring CPU VRM while the computer is starting, I get nothing. None of the VRM mosfets are shorted.I don't know what to try next.There is a videoin witch you can see the behaviour of the main 12v and 5v sata rails and the power good signal when the computer starts.
HP 8110A with faulty display GU 256 x 64  - Page 1
Forum section: electronics / repair

author: Tracker
author_rank: Regular Contributor
timestamp: November 22, 2019, 07:30:39 pm
content: Hello folks,I have a faulty a HP 8110A 150 MHz Pulse generator.But its display is blank, it appears someone attempted repair.On the display board I can see the Power transistor and Ram chip were replaced.I can measure +5 vcc on the main input.It also generates -18v, +15v and +125v which all seem appropriate.But the display docent show any sign of life.No diagrams seem to be available.Does anyone have knowledge of these displays, what should I be looking for to see if the actual display tube is faulty?Thanks

author: tagchen
author_rank: Contributor
timestamp: January 08, 2020, 11:28:33 am
content: I have paper for HP 8114A 100V/2A and a defect 8114A, but display is working.I can some measure for help?
[SOLVED] HP 8111a max amplitude cannot be calibrated - Page 1
Forum section: electronics / repair

author: gkmaia
author_rank: Frequent Contributor
timestamp: July 17, 2019, 04:16:28 am
content: Just bought a couple HPs 8111a. Both in really good condition. Absolutely everything works and can be calibrated apart from the max amplitude vernier.When turning the vernier CW the display shows 16.6V and the shaper IC U1 job is to align the max amplitude amplification to match the 16.6v show on display through a series of internal circuits.With the available calibration range I cannot achieve that. For the max amplitude the calibration range I get is from 22v to 35v.I have raised the resistance of R4 from 1.47k to 2.2k on the hope of manipulating the Iref of the opamp inside the IC. This gave me much more range to reduce the amplitude, but get into a point it starts distorting the output wave.I am suspecting U2 is shoot... but from what I can see the opamp is responsive and with good gain. But somehow the whole system diverted from spec.Anyone out there with similar problem? Or some ideas on how to troubleshoot it or pin with more certainty the U2 is in fault?
HP 8116A - Need pinout for J2 (GPIB) connector on early version 08116-66503 PWA - Page 1
Forum section: electronics / repair

author: rphilbri
author_rank: Newbie
timestamp: May 25, 2025, 04:54:45 pm
content: Help! I just purchased an 8116A that was not working. In the process of repairing the unit - now working - I discovered the A3 (processor) board is from an earlier design variant of the 8116A family, whereas the A1 and A2 boards are from a newer variant. The A1 & A2 boards appear to match the schematics from Keysight. However, my A3 board is 08116-66503 (Germany made) and the GPIB connector (J2) on this board is a 34 pin. This older version of the A3 board does not match the schematics available on-line. The schematics available from Keysight show J2 as a 24 pin connector, which is consistent with the existing 24 pin GPIB cable from the rear panel GPIB connector. So, it appears a previous owner tried to repair this unit by replacing it with an A3 board from an earlier design variant of the 8116A. I have everything working on this unit, but I now need to work out the interface between the rear panel 24 pin GPIB connector and the 34 pin J2 connector on the 08116-66503 board. I believe the older variants of the 8116A had the GPIB address switches located on the rear panel, and I suspect the 24 GPIB connector pins and the 5 to 7 address switch settings both merge into the 34 pin J2 connector on my 08116-66503 A3 board.I believe if I can get the J2 pinout (or ideally full schematic) for the 08116-66503 A3 board, I can get the GPIB interface working on this unit. I've searched on-line sources and the update information in the Keysight service manual but can't find any information on the pinout of the 34 pin GPIB connector on the 08116-66503 board.Does anyone have a pinout for the 34 pin J2 (GPIB) connector on the 08116-66503 A3 board?

author: m k
author_rank: Super Contributor
timestamp: May 31, 2025, 03:55:34 pm
content: Have you checked 8112A manuals?Pretty high probability that both machines have same connectors.406 page 8112A manual has a backdating section (377/406) where 34 pin J2 is pictured.It is also describing somewhere how 8116A is controlled, but DIP switches for GP-IB address I couldn't find.Page 278/406 has a GP-IB connector, but picture revision is unknown.

author: rphilbri
author_rank: Newbie
timestamp: June 10, 2025, 06:02:42 pm
content: I did look at the 8112 service manual but I did not think to check in the updates section. Thank you Sir!
HP 8165 Repair Board Needed - Page 1
Forum section: electronics / repair

author: Wallace Gasiewicz
author_rank: Super Contributor
timestamp: February 13, 2020, 12:02:32 pm
content: Before I go and order a bunch of DIPs and repair this board, I was wondering if anyone had a spare board that they could be persuaded to part with.Already posted on the Sell/Wanted board but thought I should also post here.HP 8165 Board A9, AY Reference Loop 08165- 66509I bought two 8165 units as junkers and have one working fine. The other one works fine if the A9 boards are switched. I replaced a bunch of bad parts, mostly op amps. The bad A9 board has problems with the 10 KHz circuit, and both PLL loops. Needs lots of DIP replacement. I thought a new board would make things easier, if anyone has one..... There is one available in EU but I was hoping for something closer.Wally KC9INK
HP 8165A can't get the top cover off! - Page 1
Forum section: electronics / repair

author: GiddyGoat
author_rank: Newbie
timestamp: November 30, 2019, 04:10:49 pm
content: It is not in the service manaul so how do I get the top cover off?I thought all I had to do was remove the rear panel feet and slide the cover back? Nope.I've remove the side panel under the handle - no help.Anybody know how to do it please?Thanks.Giddy.

author: MarkL
author_rank: Unknown
timestamp: November 30, 2019, 05:12:03 pm
content: I don't know about the 8165A specifically, but if it's like the other chassis from this era there is a single captive screw in the center of the top panel on the back. Unscrewing this will slowly move the top panel backwards and when the screw has disengaged from the threads the entire top panel can be slid backwards.The bottom panel should be similar.Just a guess.

author: PaulAm
author_rank: Frequent Contributor
timestamp: November 30, 2019, 08:35:56 pm
content: Sometimes the circlip on the screw on the inside of the cover gets lost, in which case you can unscrew the center screw entirely. If that happens, take it out then use a small flat bladed screw driver to carefully pry at the front corners of the cover. The cover has to slide back a centimeter or so before it will lift clear.It can get tight if the case has been banged up.

author: GiddyGoat
author_rank: Newbie
timestamp: December 01, 2019, 10:40:32 am
content: Thanks Mark, it was the centre screw, it was hidden by the label saying "Calibration void if removed"!Thanks all.
HP 83480A (aka 54750A) not booting - Page 1
Forum section: electronics / repair

author: Miek
author_rank: Regular Contributor
timestamp: September 23, 2020, 02:08:44 pm
content: I recently bought an HP 83480A apparently in working condition. Upon receiving it I booted it a few times and ran some basic tests, and it all seemed to be working fine. Then I went to boot it again that evening, and only got this on the screen:(ignore the hint of the UI in the background, it's just the screen burn-in - the only thing being drawn is the red junk & a purple-ish background)I've been through the service manual troubleshooting steps: I've reseated everything, checked the voltages and they're OK, voltage on the RAM battery looks OK (3.05V unloaded, ~2.9V with a couple hundred ohms load), and I checked the signal going to the CRT and it matches what's on screen so I think the CRT is fine.The other thing I notice is that there's no floppy disk activity or any response from the front panel when it's in this state, so it seems like the firmware is getting hung up somewhere.If I flip the DIP switch to force a firmware upgrade on boot, it does seem to go through the process: it reads from the floppy disk for a while, thinks for a bit, then takes the flash Vpp high for a while before turning off the disk light. So I think the boot ROM is present and working, but it just goes back to the same junk on screen after that.Then yesterday I reassembled it after debugging session and it magically started booting, albeit with some lingering weird patterns on some of the screen. I went through the self tests and they all passed except for the "video board decrementer" test. I also tried booting it without the video board connected, which didn't work before. It worked this time and I could query the device over GPIB. So I'm suspicious that the video card test fail could be a red herring, or a separate issue.Alas, this morning it's back to the original symptom of not booting at all. So, I'm wondering if anyone else has seen anything like this? Or maybe has ideas on what parts might be likely to fail and cause intermittent symptoms like this? It's a challenge to debug since the cards need to be installed in the frame to run and there's no probing access, so I'm hoping to narrow down what to check.

author: Musent
author_rank: Newbie
timestamp: May 07, 2022, 01:11:15 pm
content: Hello MiekJust some late information if you not successful to repair this HP product.I had similar problem and it run again with a good battery with a voltage near 3.3V.May be You have the same issue ...BRBruno

author: Gerhard_dk4xp
author_rank: Frequent Contributor
timestamp: May 07, 2022, 03:41:47 pm
content: Weird. I had set this "thread" on notify because I had a 54750,but in working state. Last autumn it ceased booting. It turned outit was the 3.3V lithium battery on the CPU card. After replacementit insisted into a mainframe calibration, which was easy.It just takes a signal generator.Gerhard
HP 83484a - out of range  - Page 1
Forum section: electronics / repair

author: mates
author_rank: Newbie
timestamp: July 13, 2021, 08:39:42 am
content: Hi all, I recently bought a used plug-in hp 83484A however one of the channels has excessive offset- just see the line on the top of the screen. Is this repairable or this is the end of the input?
HP 8350B solder mask replacment gold trace motherboard repair? - Page 1
Forum section: electronics / repair

author: coppercone2
author_rank: Super Contributor
timestamp: June 15, 2022, 09:14:38 am
content: So I had a 3x AA battery pack go off inside of a HP8350 generator that I got on ebay, and the solder mask coating on all the thicker traces is screwed up.When I started to clean up the residue, basically all the solder mask on thicker traces started to come off, and the planes are totally exposed now. (after cleaning it started coming off like sunburn on any trace wider then 1mm, and the traces with battery chemical damage are spotty, but the solder mask adheres better here). Pissed me off so I put it in the dishwasher and then scrubbed the rest off with a soft scour pad, so I have a fairly bright gold PCB. The surface finish is not scratched up. Not sure why only the fat traces are effected BTW. The thin ones are durable as ever, the thick ones just turned into sun burn. But maybe it was contaminated with battery crap , better safe then sorry.Since its a big backplane PCB and it has connectors soldered to it, I need a conformal coating that I can carefully paint on with a brush. I only don't need to coat a few areas with screw in capacitors and can do some fine work with a thin brush between the connector pins.The PCB is large, around 2sq feet and has a gold finish. I thought to use a MG chemicals product, but I am not sure what the best one would be. I thought about the 4200UV coating, which is UV triggered.https://www.mgchemicals.com/products/conformal-coatings/uv-conformal-coatings/uv-cure-conformal-coating/Is this a good choice? I hope these coatings can be put on bare gold finish without having a solder mask...? It is just a interconnect board, there are only some gold pins and cinch connectors on it.I heard the chinese UV-silk screen is hard to usehttps://www.eevblog.com/forum/manufacture/solder-mask/msg2206320/#msg2206320So is strait up conformal coating a better idea for a repair? Or if I don't care about aesthetics, is the solder mask paste good enough for some manual 'don't give a fuck about looks' application? I read gold poses some special problems for solder mask, so maybe just acrylic is better? I don't care if its clear, I just want it to stick to the gold good.posted this in assembly forum by accident because I was searching it. I also already have red insulating varnish from MG chemicals, but I am trying to choose the best product here, I don't mind spending a few dollars on this one if itsdurable.Not 100% sure its the problem but it looked like it might have been, I don't want to reassemble all this shit without fixing the PCB up, there is too many screws, and I have a sister unit coming in so I can work pleasant doing board swaps.. so repair probability is high and I figure ima just fix everything I find as I go.Why buy one when you can buy two for twice the price?I already have a strong UV source I made BTW (15W single LED 385nm)
HP 85 calculator repair help - Page 1
Forum section: electronics / repair

author: Gianni
author_rank: Contributor
timestamp: July 01, 2023, 11:19:16 am
content: My HP85 had some disaster and now I am trying to fix the power supply board.Currently, the problem is that Vcc = 6.5V instead of 5V. Maybe that it caused other catastrophes but to understand I must first fix the power supply.MY PROBLEM is that my PSU board is DIFFERENT from the manual. Has somebody the schematic diagram of this board? I would be very grateful.Thanks

author: cruff
author_rank: Regular Contributor
timestamp: July 01, 2023, 12:38:23 pm
content: There are lots of HP series 80 enthusiasts on thehpseries80@groups.iolist who can be of help. It would help to know which specific model (A or B) of the HP85 you have. The HP Computer Museumhttp://www.hpmuseum.net/collection_document.phphas many manuals for HP products including the series 80 systems if you haven't yet found them.

author: Gianni
author_rank: Contributor
timestamp: July 01, 2023, 04:28:39 pm
content: thanks, I will follow your suggestion

author: Gianni
author_rank: Contributor
timestamp: July 09, 2023, 06:46:46 pm
content: Just to leave a record for other interested. My is a "B" model, so I had to use the right manual. This power supply requires a minimum load on the +5V (300mA) to work. So no disaster, everything was OK and my HP-85B is up and running (besides the cassette that I am fixing).
HP 8510 VNA interconnect cables pinout - Page 1
Forum section: electronics / repair

author: wojciech
author_rank: Newbie
timestamp: September 20, 2021, 04:41:44 pm
content: Does anyone of happy owners of the 8510 VNA would be so kind and helpful and check by ohm meter what is the pinout of08510-60101(IF-Display) and08510-60102(S-parameter test set) interconnect cables? (if this is 1:1 i.e. pin1->pin1, pin2->pin2 etc or maybe some different pinout...) I own both display and detector units but unfortunately without any interconnect cables. 08510-60101 cable is pure digital so I suppose it should be relatively easy to make it by myself (90$ is just ridiculous price for such cable). 08510-60102 cable is much more complicated (mixed signal DSUB) since it consists also RF coax lines but finally I think I could eventually also make it by myself since mixed signal DSUB connectors are available on the market.I would be very, very grateful if someone could send me that information. I couldn't find it anywhere. I also read that there was never service manual (at component level) published for that 8510 VNA so I don't think there is any other place where I could find that. I was aslo asking for that information one of the test equipment sellers, unfortunately without success (probably even know why)Best regards,Wojciech

author: simmconn
author_rank: Regular Contributor
timestamp: September 21, 2021, 06:26:49 am
content: The IF-Display cable is one-to-one. The CLIP of the 8510A/B IF, 85101A display and test set boxes are available, in both hard copy and pdf. I’ve not seen a CLIP for the 85101C display box.

author: wojciech
author_rank: Newbie
timestamp: September 21, 2021, 03:14:26 pm
content: Hi simmconn,Thanks a lot for information about IF-Display cable. That's great! Would you be also so kind and could check 08510-60102 cable?Sorry for my not complete understanding - by "CLIP" you mean "component level service manual"? I was looking for that but I couldn't find it anywhere (google, ebay). I only have these from great ko4bb site. There is however no service manual with component level schematics...Best regardsWojciech

author: MarkL
author_rank: Unknown
timestamp: September 22, 2021, 05:03:15 pm
content: Artek Manuals looks like it has the full set of 8510A manuals for USD$20:http://artekmanuals.com/manuals/hp-manuals/You can ask them before purchasing if it's unclear what you need is included.They have excellent quality scans. No relation; just a satisfied customer.

author: wojciech
author_rank: Newbie
timestamp: September 23, 2021, 01:23:07 pm
content: Hi MarkL,Thanks a lot for additional information. Looks like Artek Manuals has indeed 8510A full manual, but actually I have 8510B version which was released 3 years after 8510A so I will probably search for 8510B version (probably only hard copy version is nowadays available, but I will need to make sure there are component level schematics).BTW SM from ko4bb site which I previously mentioned is actually "HP 8510C On Site Service Manual" so probably that's the reason why there is no component level schematics.Best regards,Wojciech
HP 85102B key removal - Page 1
Forum section: electronics / repair

author: matthuszagh
author_rank: Frequent Contributor
timestamp: December 24, 2020, 03:09:33 am
content: I'm cleaning the front panel of an HP 85102B IF section of an 8510C VNA. The front panel itself was easy to separate from the rest of the assembly, but the keys are also dirty and I'd like to clean them. I've attached a photo of the keyboard. Is it possible to physically remove these keys from the PCB? This is not absolutely necessary because I should be able to clean them as is, but it would make doing so easier since I would be able to soak the keys, put them in an ultrasonic cleaner, etc. I didn't see anything about their removal in the service manual. I gently tried to pull them off, but without success. Before I try with more force, I'd like to be sure they are actually removable. My understanding is that keys like these are typically designed to be removable. For instance, PC keyboards I've had have removable keys. Thanks!

author: Nusa
author_rank: Super Contributor
timestamp: December 24, 2020, 03:38:14 am
content: I don't know the answer, but I'd look at the underside of the keys with a dental mirror or equivalent to get more information.
HP 8555A spectrum analizer problem - Page 1
Forum section: electronics / repair

author: andreal1967
author_rank: Contributor
timestamp: April 19, 2021, 06:48:23 pm
content: hello everybody.i am an hobbyst who is trying to fox an 8555A RF module with my little electronic knowledge. So i ask for help.Here is the problem: the analizer work well if i select the scan bandwidth above or equal to 1mhz.If i select 500 khz scan bandwidth or less i am not able to see the signal anymore. I have to figure where is located the failure because i have another 8555 for parts that i can use for troubleshooting.here is a video to show the problem:thanks from Andrea (italy)

author: jonpaul
author_rank: Super Contributor
timestamp: April 19, 2021, 07:52:56 pm
content: Usually the rotary encoder switch wipers on the white delrin wafers behind the front panel switches.VERY intricate to disassemble , repair and reassemble.Suggest to take phots of the switches, probably will see missing switch armatures.You will get much faster and better advice on the GROUPS.IO site for HP instruments!https://groups.io/g/HP-Agilent-Keysight-equipment/topicsBon Journee, Ciao!Jon

author: andreal1967
author_rank: Contributor
timestamp: April 19, 2021, 09:36:18 pm
content: Hello jon Paul. The rotary switch was my first tought , as i have another Borrowed 8555a for test and troubleshooting i replaced the whole tuning assembly with rotary switch without solving the problem ( the tuning assembly works good on the other 8555A)
HP 8557A center frequency display issue. - Page 1
Forum section: electronics / repair

author: Raindog
author_rank: Contributor
timestamp: August 22, 2020, 02:07:20 pm
content: Greetings all. I have been working on a HP 8557A plug-in module and going through the frequency control adjustments laid out in section 5-17 of the service manual, now that that part is completed I have hit an impasse. I am now at the point where I have to set the center frequency display, however the only service manual I was able to download is for an earlier revision of this module with the mechanical frequency display. Since I do not have the correct service manual the center frequency display does not properly track as you tune up in frequency. The center frequency display gains about 40 kHz for every MHz as you tune up from 0 MHz. The display reads high, at 10 MHz the display reads 10.4 MHz, at 175 MHz it reads about 7 MHz high and at 350 MHz it reads 14 MHz high, the tuning marker in full span mode also reflects this.There are three adjustments on the digital display board labeled R6, R8 and R20, I’m assuming these are some sort of linearity adjustments but I don’t know since I have been unable to acquire the proper service manual. Has anyone out here serviced one of these plugins? Or know knows what these trimmers do? I have retired this unit from service but would like to keep it operational anyway since it’s the only “portable” spectrum analyzer I have.*Edit*I did some poking around and discovered that R6 and R8 compensate for frequency. R8 adjusts for the lower end and R6 for the upper end. Not knowing the reference frequency's to use I defaulted with 350 MHz for the upper end and 175 MHz for the lower end. Now the display has a tracking linearity of +/- 500 kHz, I still don't know what R20 does so I won't bother with it till I can find the service manual specific to my plug in module. These adjustment have also corrected the issue I was having in full span as well.
HP 8559A Spectrum Analyzer Troubleshooting UPDATE - Page 1
Forum section: electronics / repair

author: cooperg2001
author_rank: Newbie
timestamp: February 23, 2020, 12:34:18 am
content: Hello all,I recently acquired an HP 8559A and instead of the HP 182T display, it was supposed to have I received an HP 180C display. I can't get the display to show a proper trace (I only get a dot or a small vertical line) I've used an oscilloscope to verify that the 35MHz cal output is working (nice clean sine wave) so I know that wasn't the issue.If someone could advise me as to what I should check next or could direct me to somewhere I could acquire a better display I would appreciate it.UPDATE: After further research and testing I now believe the issue is with the sweep generator. If I probe the sweep generator output I do not get a signal, but if I manually sweep I see the signal change.

author: weakbit
author_rank: Newbie
timestamp: February 26, 2020, 08:56:33 am
content: That sounds like a deflection failure (horizontal) - have you any pictures to see whats happend?I've the 141T Display but this is very old and I use the Storage Oscilloscope HP54720D with the 54721A Input Modul to display the signals so it is not neccessary for me.Best Regardswekbit
HP 8560E Spectrum Analyzer Repair.  No input signal displayed. Solved. - Page 1
Forum section: electronics / repair

author: 4thDoctorWhoFan
author_rank: Regular Contributor
timestamp: July 21, 2019, 02:57:28 am
content: This post is to help anyone who might have a HP 8560E spectrum analyzer. The fault is the analyzer will not display any input signal including the calibration input signal. You will also have numerous errors like 355, 351, 353, 319, 317, 356 and 335. Your mileage will vary. Might have less or more errors.In 8 months, I bought two different 8560E analyzers off of ebay from different sellers. Once I received them and checked them out, both had the symptom listed above. I bought the second one because the display was still nice and bright compared to the first one I purchased and it was cheap. These analyzer are known for having dim displays. Anyway, both units had the same symptom of no input signal showing on the screen and it turned out that both had the same faulty part.Bottom Line: Go to the A15 board and look at the J701 output. Should be 600Mhz AND around -3dbm to +5dbm. Both of my units were spot on 600Mhz BUT the levels were around -20/-25 dbm. After some troubleshooting, the problem was U700.After replacing U700 on both units, the errors went away and the analyzer worked as it should. U700 is just a RF amp on the A15 board. It's under one of the metal shields/heatsinks in the 100Mhz distribution section. The 100Mhz gets doubled, then tripled to 600Mhz.U700 is a MSA-0505. I purchased genuine HP parts from a seller on ebay from Israel. There are others from China but who knows if they are genuine.Anyway, good luck and hope this helps get your analyzer up and running again. Since I had two units with the same fault, I thought it might be a common problem and help others.

author: bitseeker
author_rank: Super Contributor
timestamp: August 23, 2019, 04:13:34 am
content: Thanks for the info. Mine doesn't suffer from this (yet), but good to know in case it shows up later.

author: tchiwam
author_rank: Regular Contributor
timestamp: May 07, 2021, 12:23:13 am
content: Note to add here:I just found out the same trouble. Mine has :U700+9 dBm input+14dBm outputThis is taken with a 84025A and another spectrum analyzer.The rest of the chain to the 300 and 600Mhz is also low...>> The symptom is that I loose ~10dB sensitivity from DC to about 6GHz. on a 8563E <<I am ordering some from eBay right now. Would be fun to see if other amplifiers could replace that unit, it is a high gain unit nearly +8dB at 100MHz. I think they overdrive it a little the DC on the input is close to 12V instead of +8VDC or +9VDC
HP 85662A Display Flickering (8566B) (SOLVED!) - Page 1
Forum section: electronics / repair

author: pnv57
author_rank: Contributor
timestamp: May 17, 2021, 11:45:38 pm
content: Last year I bought a 8566B and display and it didn't work. I recently bought another pair (together), and fixed a YTO unlock by swapping the YTO loop, FM coil driver, and main coil driver over (all three were faulty). It been working for maybe two weeks now, and I use it quite a bit. One day I turn it on, and the display is flickering wildly, where everything on the screen kind of falls into a point in the center repeatedly. If I change the status of traces A and B (view vs blank) the frequency of which the flickering happens increases (both blanked) and decreases (both view). It ranges from ~1.5hz to ~3hz. The video output of X and Y appears to be true to what the crt shows, but when it flickers it swaps X and Y or something (My scope here doesn't have a Z, tek 2230). I've swapped A1A2, A1A3, A1A4 (XYZ axis amplifiers for the CRT) to no avail. I've also swapped the three power supply boards, as well as all of A3. When I swapped the upper half of A3, the flicker rate changed. From my meager electronics repair experience, it seems like X and Y deflection voltages leak to zero every refresh, on both traces. In addition, the 118V unreg on both psu boards reads around 90V, and the 100V unreg reads 71V on both as well. Any ideas? I've swapped everything except the A1A3 HV regulator and the IF section. I've attached videos of the screen in test modes and at startup. How should I go about troubleshooting and repairing it? I have a square/sine signal generator, multimeter, DSO scope, and a universal counter.If it wasn't the power supply, transformer, or anything downstream causing issues, that doesn't leave much. It was one of the three large filtering capacitors I replaced, that sit behind the crt.

author: pnv57
author_rank: Contributor
timestamp: May 18, 2021, 09:07:42 pm
content: More troubleshooting: I tested the three PSU boards in my other 85662a display (nothing comes up on the CRT) and in that chassis the 100V rail light comes one, and the 100V and 118V unreg test points both show good voltage. I then looked upstream, and proceeded to swap the entire transformer assembly from the other one with no display but good power. No change whatsoever, meaning that the problem either lies in the motherboard (unlikely) or that the low psu voltage is an effect and not the cause.
HP 8566B CRT focus problem - Page 1
Forum section: electronics / repair

author: jonsikul
author_rank: Contributor
timestamp: April 24, 2024, 07:04:41 pm
content: As the title suggests, I am having a problem focusing the CRT on my HP 8566B. When adjusting the focus on the front panel it is like I just need a half a rotation more and then it would focus but the focus screw doesn't allow for that.Is the CRT just weak?I just got this machine from an auction without any description on how it works, so I am turning it on for the first time.

author: Greybeard
author_rank: Frequent Contributor
timestamp: April 25, 2024, 07:15:19 am
content: Check all voltages at the CRT.Check resistance of all resistors and potentiometer in the focus resistor chain and check solder joints.May be this helps:https://www.jvgavila.com/hp8566a.htm
HP 8566B Spectrum Analyzer No Check Lights, Display Output or GPIB - Page 1
Forum section: electronics / repair

author: cestevens
author_rank: Newbie
timestamp: March 14, 2024, 11:04:22 pm
content: Hello all,I recently got my hands on an HP 8566B Spectrum Analyzer.Unfortunately it would appear the deal was too good to be true, as the instrument appears non-functional.I've attempted to follow the troubleshooting guide, but I'm not sure where to go now with the information I have.When powering, the CHECK INST I and II lights should go on, then power off.Currently they never turn on in the first place, remaining off the whole time.I think this would implicate something to do with the CPU board.Accordingly the display unit and GPIB interfaces are unresponsive as well.I haven't found any part of the manual that describes what to do continuing from here.I have attempted reseating all the boards I can.The regulated voltage lines all seem okay, unregulated are generally a little further out but within what I guess to be reasonable.If anyone knows what I ought to try next I would appreciate it.

author: m k
author_rank: Super Contributor
timestamp: March 23, 2024, 02:01:58 pm
content: Not exactly very simple device.No LEDs ever can also mean that power is not connected further.Standby LED(DS1) should be on when machine is in standby state.Somewhere is also an overtemp sensor.
HP 8566B spectrum analyzer trace flicker/glitching - Page 1
Forum section: electronics / repair

author: tonycox01
author_rank: Contributor
timestamp: January 14, 2020, 10:06:54 am
content: Hi,I recently got hold of an HP 8566B SA which largely seems to be working OK apart from a random flicker/glitching of the trace display. The trace appears to break down in to a flurry of horizontal lines at random intervals and positions. I've trawled for similar issues with the 8556B but not come across anything so I thought I would ask a question here before diving in to serious troubleshooting - just in case anybody has seen a similar problem or has any suggestions about where to focus my troubleshooting efforts.I have created a short video that demonstrates the issue (this brief capture was from the self calibration routine).https://youtu.be/LvoDBJFQfnMthanks in advance for you help/suggestions.Tony

author: jfphp
author_rank: Regular Contributor
timestamp: January 14, 2020, 10:11:20 am
content: I will try with the power supplies (ripple) mainly those going to the display board.

author: tagchen
author_rank: Contributor
timestamp: January 14, 2020, 10:28:37 am
content: in this old measurement tools check power supply caps, mostly higher voltage (400-450V) are the problem.this problem can be keramic caps for digital chips (cpu boards or so)have you picture from inside?installing retrofit document can little help.08566-90151-retrofit.pdf(4410.18 kB - downloaded 108 times.)service and repair manual to big to post, find in keysight pagePart Number: 08566-90042 (Dec84). This manual is provided for information only. The 8566B and 8568B are no longer sold by Keysight. Note: the file size is 36.37 MB.

author: tonycox01
author_rank: Contributor
timestamp: January 14, 2020, 01:40:35 pm
content: Thanks - no picture yet but I'll try and get some.I'll start with the caps on the power supplies and see where that goes.cheersTony

author: Johnny10
author_rank: Frequent Contributor
timestamp: January 14, 2020, 02:39:10 pm
content: I might check for input power line noise.
HP 8566B YTO unlock repair: unexpectedly easy - Page 1
Forum section: electronics / repair

author: Bill Woodbridge
author_rank: Contributor
timestamp: September 28, 2022, 04:07:41 pm
content: A quick note in case it might help someone else with this common fault, plus my recommendation of a tutorial.I recently became the proud owner of the mighty HP 8566B, advertised with the YTO unlock problem on the 2-22GHz mode only. Before I collected the unit, I tried to read up on the principles of operation (which scared me) and also did a pretty comprehensive read-through / viewing of most of the online material: Youtube, this forum, groups.io etc.There are of course some very good and well-known Youtube videos tackling this exact problem, but in the end I found the most useful to be those from 'DKD Instruments'. They're well down the list on the Youtube search, and not at all glamorous: the video content mostly consists of a general view of the open RF unit under fairly dim light, but the presenter (unusually) gives a wide overview of possible faults and their likely causes, plus his opinion on their relative likelihood, in his (clearly considerable) experience. I found this ultimately more useful than viewing the specific 'eureka' stories that most of the other content consists of, entertaining though they are.Anyway, for better or worse the DKD Instruments advice convinced me to park the theory and my lovingly-drafted strategic plan in favour of going for broke by just replacing C7 on the A20 board before investigating anything else at all (to be fair, other repairers also mention this specific component). It's a 10uF capacitor - mine read 9.1uF out of circuit, it looked a bit shabby but not obviously blown, so my hopes weren't high of making any difference (I don't have an ESR meter). To my huge surprise, the YTO unlock fault, previously present on every combination of span and centre frequency that I tried in the 2-22GHz mode, instantly disappeared never (or at least not yet) to return.So that was my own 'eureka' story. A sample of one instrument isn't really significant, but I'd upvote A20C7 in the recommended investigation priority list, if there was such a thing, and highly recommend DKD Instruments' material.
HP 8568A Spectrum Analyser not booting up. Both INSTR CHECK Leds on - Page 1
Forum section: electronics / repair

author: sm6413
author_rank: Newbie
timestamp: September 20, 2024, 07:22:14 am
content: Hi everyone. I bought a dead HP8568a spectrum analyser that does not boot. Both INSTR CHECK leds come up and stay ON.The seller i bought it from tested the top "screen" part of the analyser on a known working HP8568B and confirmed the display part worked just fine. So the issue is not from the display.Has anyone here experienced a similar issue where both INSTR CHECK leds stay on? What did you do to fix it?Seems like the first thing to do is to clean all the contacts on the connectors and check continuity. Haven't tried anything yet.Thanks everyone
HP 8568B cables, CRTs and other stuff - Page 1
Forum section: electronics / repair

author: bdunham7
author_rank: Super Contributor
timestamp: September 13, 2020, 04:23:50 am
content: I've got an HP 8568B duet that I'm trying to evaluate for a surplus equipment dealer to see whether it can be fixed or parted out. I'd like to do as much testing as possible even if it is parted out because I don't want to ship out any parts I'm not reasonably sure are good.The first issue is cables. They've been looted, of course, earlier in the surplus equipment foodchain. So we obtained cables from an HP 8566B, which look the same but have different part numbers. Does anyone know for sure whether they interchange? I have no idea why they wouldn't, but you never know.I connected them with those cables and found the CRT completely blank. I connected an oscilloscope to the X/Y/Z terminals on the back and got a display and for a few moments everything looked good. I started setting it up to look at a signal and it froze, then started again and so forth. It showed me a message 'Oven Cold', then froze again. I thought it might be a display issue, but the buttons stoppped doing anything and the LEDs didn't change. I managed to get a display of a signal at one point, even changing the input connector selection, but more often than not, the buttons don't work at all on either section. The only button that consistently responds is the INSTRUMENT PRESET button, which will make several LEDs come on and then go off again.So I'd like to know for sure that I'm not causing this with the cables for some odd reason.I'm pretty sure I'm testing a parts unit at this point. The CRT was loose and appears to have been removed or something and the connector was only half on. Perhaps someone tried a rejuvenation and killed it? The units are in reasonably good physical condition, so if anyone needs anything...

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: September 13, 2020, 04:33:50 am
content: Hi,Check here for a summary on the cables:https://www.glkinst.com/cables/hp_cables.htmThe 8566/68 is about 2/3 rds down the page.Jay_Diddy_B

author: 0culus
author_rank: Super Contributor
timestamp: September 13, 2020, 05:17:55 am
content: The cables are the same between the two. You can easily make the coax bundle yourself. The centronics cable not so much, and they are worth a pretty penny.
HP 8568B YTO ERROR help - Page 1
Forum section: electronics / repair

author: andreal1967
author_rank: Contributor
timestamp: February 13, 2024, 09:45:45 am
content: Hello , my HP8568B spectrum analyzer has a "YTO ERROR" on display when the frequency span is UNDER 1 MHZ and the center frequency is around 900-1000 mhz (there are holes where the error disappears in the middle) . When the error is present, there is a "249 mhz unlocked" led ON LIT on the A8 board. With span under 1 mhz , the analyzer work flawlessy on ani frequecy and the YTO error is also not present under 900 mhz frequency at any span.I measured all voltages and are in spec. I tried an external 10 mhz reference and no difference.I cannot find online the 8568B manual, so i am stuck.I need help...

author: Runco990
author_rank: Frequent Contributor
timestamp: February 13, 2024, 04:59:56 pm
content: Watch Curious Marc's video on this. It's a common error caused (usually) by a capacitor.Hope this helps.

author: andreal1967
author_rank: Contributor
timestamp: February 14, 2024, 02:35:21 pm
content: i watched the "curious marc" video. It was really useful. I repaired the SA, just tweaking a variable resistor.

author: Runco990
author_rank: Frequent Contributor
timestamp: February 14, 2024, 10:17:31 pm
content: Glad it helped you fix your Spectrum Analyzer.
HP 8560A-8563A 4 ROM Firmware Version 920504  - Page 1
Forum section: electronics / repair

author: thorswait
author_rank: Contributor
timestamp: September 14, 2021, 02:09:55 am
content: Hi everyone,I would like to know if anyone have ROM revision 920504 4 ROM module that would like to share it's binary with me and everyone. I have an 8563A with ROM revision 911108 upcoming and would like to upgrade it to it's last revision.I'll share my revision as soon as I receive the unit.Thanks

author: pnv57
author_rank: Contributor
timestamp: September 14, 2021, 11:45:18 pm
content: Will either of these work?http://www.ko4bb.com/getsimple/index.php?id=manuals&dir=01_ROM_Images_and_Drivers/HP_8561_8562_8563

author: thorswait
author_rank: Contributor
timestamp: September 15, 2021, 02:01:30 am
content: If you take a look at the firmware history pdf I attach The 856xE and 8561A 8562A/B are a different from the 8560A/8561B/8563A series so it won't work.

author: thorswait
author_rank: Contributor
timestamp: September 25, 2021, 03:41:04 am
content: As promessed earlier here is a copy for the 911108 ROM version from my 8563A.
HP 8590A off frequency - Page 1
Forum section: electronics / repair

author: Crambone
author_rank: Frequent Contributor
timestamp: August 20, 2019, 06:11:21 pm
content: I have an HO 8590A Specrum Analyzer that is off frequency by 2-3MHz. It passes the CAL tests.Any suggestions were to look or what to try?

author: MarkL
author_rank: Unknown
timestamp: August 20, 2019, 06:44:59 pm
content: Please don't double post. There were already a couple of responses to your question:https://www.eevblog.com/forum/beginners/first-spectrum-analyzr-hp-8590a/msg2628522/#msg2628522
HP 8590L sectrum analyzer no power - Page 1
Forum section: electronics / repair

author: whatboy
author_rank: Regular Contributor
timestamp: February 17, 2022, 09:02:45 pm
content: Most of the times, but some times when cold, power up gives video, then shuts down, and have to unplug and wait a few minutes to try again, lasting less and less power on, what I have notice is that the -15V rail led, doesn't lid with the rest of rails, and after a few seconds lids on and then off, then the unit dies, and the impedance of that rail is 10.5 ohms, managed to notice a shilded module that if I disconect the impedance goes up, but even if I disconecf the module, the unit acts the same, starts up, then shuts down, with or without the module... any one has the schematics of the power supply??? 5062-8229Thanks in advance!!!

author: whatboy
author_rank: Regular Contributor
timestamp: February 18, 2022, 12:37:38 am
content: Open up the shilded module, and found one coil L1 really burned, not open... and the low impedance is on C4, there must be something bad...

author: whatboy
author_rank: Regular Contributor
timestamp: February 18, 2022, 02:07:41 am
content: Well, now it stays on, but without the shilded module, wonder if there is anything else wrong, could buy that module but, if something else is wrong?

author: whatboy
author_rank: Regular Contributor
timestamp: February 18, 2022, 02:18:37 am
content: Like what is this?? Marked as BS2, and besides it is another marked BS1, number 2 has light, like a led... the other does not...
Hp 8591E Power supply - Page 1
Forum section: electronics / repair

author: sampler1
author_rank: Regular Contributor
timestamp: March 06, 2020, 04:34:42 am
content: Hi All,I will be receiving a dead HP8591E spectrum Analyzer. From what I have been told its a power supply issue. I have also read there is no supply clip because it was made by someone else for HP.I also read tonight the HP 8560E has a very similar supply. So far I tracked down the service manual with troubleshooting and Block diagrams.. Does anyone have any info as to where I can find a Power supply clip?Best regardsGarry
HP 8593A 22 GHZ Spectrum Analyzer - Distorted signal view after self-calibration - Page 1
Forum section: electronics / repair

author: John_ITIC
author_rank: Frequent Contributor
timestamp: August 27, 2021, 03:51:47 am
content: Hello. The troubles continue with my Ebay-bought 8593A. It appeared to work well until I ran the self-calibration. Afterwards, the signal appears distorted (both cal signal and from external siggen). This happens even with the calibration corrections turned off. I went through the 8593E service manual (none found for the 8593A) and I'm currently on step 5 in the adjustments procedures section (5. Crystal and LC Bandwidth Filter). I made the crystal shorts and got stuck at the beginning because the signal doesn't look symmetrical like in Figure 2-9.I have attached the section from the service manual with the 2-9 reference picture. Also attached is my SAs distorted signal view.Has anyone seen anything similar in the past? Any idea where to start looking?Thanks,/John.

author: John_ITIC
author_rank: Frequent Contributor
timestamp: August 27, 2021, 03:53:09 am
content: XTAL short locations attached