HackSpace's HP1630 Logic Analyser, faulty display - Page 1
Forum section: electronics / repair

author: tggzzz
author_rank: Super Contributor
timestamp: May 30, 2015, 09:43:55 am
content: Bristol HackSpace has just been given an HP1630A logic analyser complete with probes etc, which would be a useful addition to their test equipment.It powers up, PSU voltages are correct, display appears correctly - except that the characters are mostly semi-solid rectangles. Has anyone seen this before?My suspicion, without evidence, is that the EPROMs may be corrupted. If so, are there any images that can be downloaded so we could re-blow the EPROMs?Thanks tohttps://www.eevblog.com/forum/repair/hp1630d-logic-analyzer-repair/msg253264/#msg253264I've been able to locate the service manual, but haven't digested it nor have I poked around in the LA.

author: Andy Watson
author_rank: Super Contributor
timestamp: May 30, 2015, 10:38:31 am
content: Is there any text? If all the text appears as blocks I would suspect something down-stream of the text rom.I can probably copy the rom contents from a 1630G - but it will be at least a week before I can get access.

author: MarkL
author_rank: Unknown
timestamp: May 30, 2015, 01:57:35 pm
content: If everything else is working normally I doubt it's the program ROMs/EPROMs.There is a separate character generator ROM (U6C) on the processor board. I would start looking at it and its associated circuitry.The service manual describes how character generation is supposed to work in section 8B-29.

author: MarkL
author_rank: Unknown
timestamp: May 30, 2015, 08:01:23 pm
content: I should also point out that these particular units are very easy to work on. The service manual is very detailed, and the unit has a built in extender slot so you can pull boards out the back and stick them in the top for debugging. Pic below.Someone put a lot of thought into serviceability and longevity. It's too bad they became obsolete so quickly.It may still have some usefulness at the hackerspace, if at least for the learning opportunity in debugging it.

author: tggzzz
author_rank: Super Contributor
timestamp: May 30, 2015, 08:34:12 pm
content: Thanks for the responses and ideas.We can't tell how much of the LA is working, because the display doesn't show anything useful. It is believed to have been operating before being stored, so there's good reason to hope it can be resurrected.The only change we can see is that after maybe a minute the "semi-solid rectanglar blocks" change appearance slightly, but only once. That tends to mean something different is trying to be displayed, but there's insufficient information as to whether or not that is because the processor/program is functioning correctly.The built-in extender card is very nice; I had noticed the socket and wondered what it was!As for "learning opportunity", we have plenty of them, and some of us are quite adept at resurrecting 70s/80s scopes and plottersPersonally I can't be bothered with scopes (other than my HP1740), but since we don't have an LA I'm prepared to put some time in.

author: Andy Watson
author_rank: Super Contributor
timestamp: May 30, 2015, 08:42:17 pm
content: Try the WFORM key. This overlays part of the display with a graphical (rather than text) video rendering. If it doesn't work you might have an issue with the software/firmware and/or processor.

author: tggzzz
author_rank: Super Contributor
timestamp: May 30, 2015, 08:48:51 pm
content: Quote from: Andy Watson on May 30, 2015, 08:42:17 pmA useful diagnostic tip. We might have pressed that button when we were imitating a million monkeys, but can't be sure.I last used one of these in ~1980, so I've forgotten how they work and haven't had time to sit down with a manual.

author: artag
author_rank: Super Contributor
timestamp: May 30, 2015, 09:10:53 pm
content: I remember these machines as being wonderfully easy to understand and work with. They may be rather limited compared with later models, but the manuals are good and the UI is sensible - it seems to reflect the actual hardware, so you feel as though you know what it's doing. I particularly liked the G model for its software performance features. I thoroughly recommend them for learning how to use a LA, great for a hackspace.

author: marshallh
author_rank: Unknown
timestamp: May 31, 2015, 04:19:02 pm
content: Open it up and reseat all the cards with edge connetors. Then check the PSU outputs

author: MarkL
author_rank: Unknown
timestamp: May 31, 2015, 07:35:52 pm
content: Quote from: Andy Watson on May 30, 2015, 10:38:31 amAccording to the manual, the 1630G has a different CPU board and different ROMs.I wouldn't be ready to blame the EPROMs yet, but attached are a copy of 1631D EPROMs if things start going in that direction. They should run in 1630A/D and 1631A/D models.Quote from: tggzzz on May 30, 2015, 08:34:12 pmPerhaps turning down the brightness control pot on the CRT will expose what (or if) characters are there. Something's obviously not right, but maybe you can see what it's saying.On boot, you should get something similar to the pic below. But all little rectangles if I'm understanding your description?EDIT: Added HP part numbers that appear on the EPROM labels to the readme in the zip file.

author: tggzzz
author_rank: Super Contributor
timestamp: May 31, 2015, 07:44:58 pm
content: Quote from: marshallh on May 31, 2015, 04:19:02 pmUnfortunately we did all that while cleaning out the dust, plus re-seated the socketed ICs.

author: MarkL
author_rank: Unknown
timestamp: June 01, 2015, 02:44:32 am
content: While we're on the topic of 163x logic analyzers, I have a quick question (actually for anyone with a 163x):Which way does the air flow in your unit? Does the fan blow air out the back, or suck it in and blow it out the side?I think someone replaced my fan long ago and I'm suspicious that they put it in right. It's blowing out the side which seems a little unusual.

author: Andy Watson
author_rank: Super Contributor
timestamp: June 01, 2015, 09:43:08 am
content: Same as your unit - sucks in through the fan, blows out through the side.

author: BloodyCactus
author_rank: Frequent Contributor
timestamp: June 01, 2015, 12:44:25 pm
content: hook gpib up and see if you get a valid response over it to know if its working or not

author: MarkL
author_rank: Unknown
timestamp: June 01, 2015, 07:34:58 pm
content: Another simple sanity check is to push the PRINT button. The 1630 will beep it tries to start printing, and then it will beep again after a couple of seconds and display an error when it can't find a printer. The STOP button clears the error if you want to try it more than once.