HP27 Restoration (Lots of Corrosion)

[GreyUser]

Also noteworthy is that the 27 was built exclusively with one-of-a-kind HP nmos process technology, it has no interchangeable ic’s with any other hp model. Note the very non-standard (for hp calcs) voltages shown on Tony’s schematic.

White vinegar in an ultrasonic cleaner is your friend for removing that level of corrosion. Yes, some of those traces will be open afterwards but that will happen regardless of the method used.

The traces can always be repaired. I’d be more concerned with the level of corrosion that has found its way into the keyboard flex strips. That’s the real challenge.