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[meverylame]

Hi guys,
I recently purchased a pair of (broken) Lexicon 224s, which I have successfully brought (both) back to life. I came in to today that overnight the ac had stopped working and was greeted with sound of my beloved 224 outputting white noise rather loudly. I rebooted it found that it was booting a e80, e82, and e87 codes, which the manual points as the ARU board. I swapped ARU boards and it came back to life immediately.

So knowing that it is the ARU board I pulled my broken board and wrote down all of the chips and then looked then of which it occurred to me, is there a substitution chart anywhere for logic chips? Also is there any advantage to rechipping the entire board as opposed to just chip swapping with the other board to isolate the problem and then replacing just that chip?

[radardoug]

One of the biggest problems with these, is the sockets stop working properly. If you wriggle all the chips in the sockets chances are it will leap into life. If you are really keen, replace all the sockets with good quality turned pin types.

Regarding changing chips, a lot of LS series chips can be changed directly for the HC or HCT families, but with Lexicons you cannot just change them all. Some positions are critical, usually for timing reasons.

[zmix]

That's great advice, Doug.  For the most part these chips are fairly robust but the sockets and connectors accumulate a lot of oxidation over 30 years.