LC III - odd problems — #15

Post #15 by thekhakinator

Source Forum	LC III - odd problems — #15
Category	Hardware
Post Date	Tue, 17 Nov 2015 - 09:19
Original URL	https://68kmla.org/bb/threads/lc-iii-odd-problems.2858/

Post

Macdrone said:
weird, did you try removing the fpu? Maybe some pins are crossed or corroded. I know from experience I cut fpus off of bad blow up boards to put in color classic and LC's and if those pins are not striaght it can get crazy. Just a thought. Also I could not read the speed on the fpu, if its 16mhz and the board is 25mhz or better that may be the heat issue and a heat sink on it may help.

Its not been upped to 33 mhz has it? if so that could be overheating the cpu also and it would need a heat sink.

Just suggestions to look at. Did not see any of this mentioned.

Yeah, tried it with the FPU out. No improvement. I've put the FPU in my other LC III. Fairly confident it hasn't been upped to 33MHz. How would one check that? I'm not familiar with the mod.

techknight said:
you know, with as many mac logic boards that I have repaired, I think I only have ever seen 1 bad GLU. and that was due to pin corrosion/rot.

Yeah, that was my leading theory - I expected it to have some sort of pin-related problem rather then being inherently dead. Unfortunately I'm not particularly skilled in reflowing big QFPs. My attempts thus far haven't really netted me any success.