Re: OT: Classic Macs group?

["jsnospam@cimmeri.com" <js@cimmeri.com>]

Thank you very much, Schmidtd, BenYates, SimonWilliams.

Hi Michael!

> Ticking can be caused by an overload (does it still tick if the
> power supply is disconnected from the load?) or by an internal
> fault.

I have two Mac Pluses.. which apparently have a nearly identical
analog board to the 128k + 512k machines.   Both have the same symptop
-- a faint ticking sound that occurs irregularly about every second or
so..  I stress irregular.

One Mac Plus is the spare power supply / logic board for the other.

Yes, I have a voltmeter, oscilloscope, etc.   I also have schematics
for various sections of the analog board.   This is an interesting
board to learn switching power supply and video circuitry from....
which I think will be my goal now.

I note that there are 3 spark gap capacitors used for transient HV
surges.. I wonder if one or more of them is sparking?

~ J