Dotts on CRT For A HP3582A Audio Spectrum Analyzer - Page 1
Forum section: electronics / repair

author: kml183
author_rank: Contributor
timestamp: July 09, 2025, 02:38:46 am
content: Hi y'all!I got an HP3582A a couple of years back. The last time I turned it on was 12 months ago. When I turned it on a week ago, my CRT display was showing dots, lines, etc, instead of the standard display. Here are the things that I have tried to debug the issue:1. Reset the device2. Change the contrast on the displayBefore I pull it apart to start looking at the display driver, is there anything obvious I am missing here? Thanks!

author: squadchannel
author_rank: Frequent Contributor
timestamp: July 09, 2025, 02:44:54 am
content: Is it problem of psu?https://youtu.be/KwBMKfV1LWo

author: Kean
author_rank: Unknown
timestamp: July 09, 2025, 03:07:55 am
content: Quote from: squadchannel on July 09, 2025, 02:44:54 amNever worked on these, but it looks like a very different issue. The display seems to be stable, but garbage. Could be power related, but I suspect not the HV part.Even the character decoding seems a little suspect as those symbols don't seem to match the display map - although it is hard to be sure, and maybe some are the square root symbol?Out of interest is there any response from the front panel? If not, the issue may be more than just the display controller/driver.The service manual is available and has reasonable info and troubleshooting, but seems to rely on having access to a 5004A signature analyzer.https://www.keysight.com/au/en/assets/9018-04019/service-manuals/9018-04019.pdf

author: kml183
author_rank: Contributor
timestamp: July 09, 2025, 03:29:07 am
content: Ya I don't have that tool. I have a HP Spectrum analyzer and a Oscilloscope. I think want I am going to try is to proQuote from: Kean on July 09, 2025, 03:07:55 amYa the contrast knob and reset buttons work. From what I understand these analyzers use memory to store characters I wonder if that memory could be corrupted because all of the characters are bad like you said? I am also going to check to make sure all of the cables are connected, caps are good etc. I don't really have the ability to probe the sync and video lines though :/

author: Kean
author_rank: Unknown
timestamp: July 09, 2025, 03:35:57 am
content: OK, that sounds promising. I wonder if it is an address decoding issue, or a buffer gone bad.While having my lunch I was browsing the service manual and found a few interesting paragraphs:Page 8-3QuotePage 8-6QuotePage 8-7Quote

author: Runco990
author_rank: Frequent Contributor
timestamp: July 09, 2025, 03:37:19 pm
content: I own 2 of these. It could actually be a SUPER COMPLEX problem, requiring many hours of troubleshooting.I suggest you START by simply re-seating all the plug in boards first, as this has been the problem with both of mine after sitting a long time.THEN, if still the same symptom.... check Tantalums.... those wonderful Tantalums.Good luck!

author: m k
author_rank: Super Contributor
timestamp: July 09, 2025, 06:44:36 pm
content: It's clearly a digital addressing problem.Upper side has every other character as 'V' with a missing pixel from upper left, others are mostly parts of 2, 4 or 5.Lower side is mostly full of those V characters and only few others.Bad contact is a very promising guess.Is correct last of upper right a 'V'?E,is it so that both of last of lower text lines are 'V'?