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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.

Tom, Thanks for pointing this out. I was on the way out the door when I wrote the post and overlooked some details. From what I can gather from the scatty information I have it appears that they are

Hi, following the other topic that I started but then closed, I am now facing what I think is the real issue. Without the card, the CAL is successful. However, when the card is installed, it fails at

Or look for an avionics shop that might be interested in it, and then get something you might use more regularly. Steve

Yes, I understand, just be sure you look wherever you can see them. Can you get any sense of where the smell came from? Did you see any smoke? That would be a good place to look. Burned resistors are

Thinking of fuses, a 1 amp fuse doesn't blow at 1.1 amps. Certainly Chemical fuses (resettable) say may blow in 30 seconds at 2 amps, maybe 5 seconds at 4 amps, and almost immediately at 10 amps.

"Bruce" <bruce@...> writes: I didn't notice any burned motherboard traces when viewing the bottom of the unit. Unfortunately, viewing motherboard traces from the top is a bit tricky. Matt

Be sure to examine the motherboard for burned traces. Quoting Matt Huszagh <huszaghmatt@...>:

Hi Yep, got a sensor, although privacy not going to be measuring many pulse signals. Probably need to experiment to see what uses I can find for it Steve