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"Harvey White" <madyn@...> writes: I did check these, however, I couldn't discern any smell coming from the RIFA or the input filter, so I think they're probably not the source. I'll

I came across an old HP price list from 1971 where HP was asking a whopping $8.55 for the 5082-2308 matched pair. The matched quad was $27.15. At that time HP was also offering the individual

Here is a video of the malfunction. Typically on first start up in the morning it runs normally and then slowly drifts into this state you see. The capacitor being attached is a brand new mica 820pF.

------ I think your question is if -10V is supplying 1.5A from your measurement why a 5A fuse. ?Fuse in -10V section carries current of -5.2V supply in addition to -10V. The fuses are there in case

So many very good responses. The old smoking tantalum cap issue. How many pieces of HP test equipment have I picked up for little cost because of those. I think shorted tantalums are my friend. That

Yes, indeed, matching to that level in general requires not insignificant effort, hence the reference to cost. However, if the diodes aren't from a random collection, but rather from the same general

---------- Easier to guess for the supplies with IC regulators but a back of the envelope guess: +28V -> 1.5A -12.6 -> 1A +15V -> 3.7A -15V -> 3.1A +5V -> 7.8A -5V -> 1.4A These estimates depend on

Craig >

The cmp file is compressed, if I remember correctly it's a scheme similar to LZ77 or LZSS. I ended up desoldering the eeprom used for the bootloader (there's a 17th one off to the side of the main

I have seen the power rail pass transistors fail - they are actually socketed to the motherboard with copper rivets. Failure mode: sometimes corrosion (copper oxide) between the motherboard and the

Great job!?What is that cmp file format - uncompresed from firmware release for 54750 unit ? Is it some sort of disk image ? can't open it by Ghidra, code analysis doesn't show anything for mc68k my

Basically just from spending lots of time staring at the disassembly in Ghidra and making educated guesses about what the code is doing. I've attached a screenshot of the relevant parts of the code.

"I'm not rich enough to use cheap tools" -Dave

"Bill Martin" <wwm@...> writes: Interesting idea, I hadn't thought of that. Thanks Bill!

Right about HP; one of my former colleagues said it stood for "High Prices"! Jim Ford

Perhaps try sniffing through a latex or some other very flexible hose that can get you smell samples from close to the pcb? Sort of like the old mechanics "stethoscope" noise finder... Bill

A good place to check for burned smell would be the RIFA capacitors on the power input.? They're filters, and fail (especially often) in 240 volt land. The equipment will work without them, but they

"Bruce" <bruce@...> writes: I did see a little smoke. Unfortunately, I wasn't expecting it and was more preoccupied with turning the unit off, so I didn't get a clear idea of the origin. I

Hi Greg, Thanks for that -- I would've guessed that they would shoot for deltas of 10% or so, and those numbers are within ~2x of that guess, so 20mV and 0.2pF seem perfectly reasonable. In sampling

"Harvey White" <madyn@...> writes: Interesting. Why wouldn't the designers use a fuse closer to the max current draw? FYI it is the right fuse, I'm just taking the value from the manual.