Thanks James,

Yes that crossed my mind also. Reseating those ICs on the controller board was one of the first things I did.  The Profile is in remarkably good physical condition for it's age.  It's obviously been well cared for and stored in a dry environment.  There are few signs of corroded "black-leg": chips.  I've certainly seen a few of these in my other classic computers when repairing them.

Terry (Tez)


On Mon, Jan 23, 2012 at 9:13 AM, James MacPhail <gg_@sigmasevensystems.com> wrote:

My experience with these kinds of symptoms is that it is a marginal ProFile Controller Board IC socket contact. This would explain such things as the controller sometimes finds the HDA in working order, but cannot communicate with the Lisa, and why the self-test sometimes works and sometimes doesn't.

The usual fix is to extract each IC a little (pry up each end, say 2 mm), then push back into place. If that doesn't fix it, pry up each end slightly and try that (without pushing them back in).

I have also seen ProFile Controllers with substantially corroded chips... very dark legs. Pulling out the worst ones and cleaning the legs back to shiny silver with a pencil eraser can fix those (but do one chip at a time to make sure you get it back in the right place, and triple-check they are all inserted the correct way around before turning the power on). The legs are fragile of course, so you clean them lengthwise while supporting them so they don't bend.

Sometimes removing and re-inserting each chip a few times is enough to clean the contacts. You might try that before using the pencil eraser.

Good luck!

James

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