exxos's Atari, Amiga & retro forum

lilwashu wrote: 28 Feb 2024 17:11 It needed a CPU change because of the cap damage eating the pins:

Ah, fair enough. :-)

It's fair to say my CPU replacement attempt didn't go well (cough) so I gave up at this point before messing it up further.

:-) Always a good plan!!! :-)

First job will be getting it from work... after that lots of flux and hot air to take the chip off, then clean up.

PhilC wrote: 28 Feb 2024 17:32 There are a few floating pins anyway on that CPU but even without looking too hard it’s obvious there are plenty of errors to fix, hopefully once you’ve sorted the bridges out it’ll boot.

I may have one or two spare chips from a donor LC-II if they are the same.

Also sure there shouldn’t be a missing chip??

That's a socket for the 68882.

(U25 is optional and U38 doesn't even appear on the schematic.)

stephen_usher wrote: 28 Feb 2024 18:09

PhilC wrote: 28 Feb 2024 17:32 There are a few floating pins anyway on that CPU but even without looking too hard it’s obvious there are plenty of errors to fix, hopefully once you’ve sorted the bridges out it’ll boot.

I may have one or two spare chips from a donor LC-II if they are the same.

Also sure there shouldn’t be a missing chip??

That's a socket for the 68882.

(U25 is optional and U38 doesn't even appear on the schematic.)

I know about the 68882, it was the other I meant but ok.

You can get external cpu boards from eBay for around £50 that Will possibly work on that. Also to make things easier to diagnose, most cpu pins, address & data bus will be on the expansion slot making it far easier to get a scope probe on to it.

@lilwashu Personally I'd have got a Dremel out on that CPU and soldered wires to bridge from the internal parts of the pins and the remains of the pins on the board. Far less risky.

stephen_usher wrote: 28 Feb 2024 18:33 @lilwashu Personally I'd have got a Dremel out on that CPU and soldered wires to bridge from the internal parts of the pins and the remains of the pins on the board. Far less risky.

I did try this but there was so little good metal left I couldn’t get enough of it exposed. Several of the other pins that were under the cap juice disintegrated when I took the CPU off.

All the pads were in good order except one that wasn’t connected to anything (may not be the case post-cpu install attempt).

Well, that's a good start to the weekend. The off-side front suspension on my car has collapsed.

stephen_usher wrote: 01 Mar 2024 19:17 Well, that's a good start to the weekend. The off-side front suspension on my car has collapsed.

Oh crap, not what you needed with a busy weekend ahead.

Got the SAAB operational again after charging the battery so managed to get to the model railway show to help out. I've not had a chance to look at the BMW since last night though. It's parked in the road so that I can get the SAAB out but even getting up at 7am I didn't have time to even think about looking at it as I needed to get to the venue, and it was dark by the time I got home. It's going to be the same tomorrow.

This evening I managed to fit the Z80 SIO/0 into the Kaypro and re-terminate the keyboard cable (was a phone handset cable) with RJ11 plugs which have the release spring lever not cut off (as the originals had). Also made a few more foam cylinders for the Apricot keyboard then found that I will need double that to finish the job. Still they're easier to cut out than the mylar circles as the punch doesn't go right through most of the time.

Got the day off tomorrow to try to get the BMW to a garage. It should mean that I have the afternoon free to get on with the Apricot keyboard.

stephen_usher wrote: 04 Mar 2024 14:02 Got the day off tomorrow to try to get the BMW to a garage. It should mean that I have the afternoon free to get on with the Apricot keyboard.

At least you were able to get out in the SAAB, which is something. What's exactly happened to the BMW? Sounds like maybe a spring has failed, fingers crossed nothing more serious than that.