wrote:
Someone else suggested testing the output of CR.

It's an easy test. You have to do it with the board powered on -
it needs input current to work. Basically it's a diode, and when you
put current through it, it will very reliably drop 1.23 V across itself.

One or both comparators in U8 probably use this steady 1.23 V to compare
against some external signal.

I was going to look at the datasheet online to see what it is supposed
to be putting out but your post has that info, which will save me some
time.

I found the full datasheet for your part number at
http://www.mouser.com/ds/2/256/icl8069-299952.pdf - this part is by
Maxim. The part number suggests that it was originally made by Intersil
and their data sheet is at
http://www.intersil.com/content/dam/...l8/icl8069.pdf
..

All the components listed are what actually populates the board. I
used my 10x magnifier to get all the part numbers that are on the
list.

Ah. I thought maybe the list came from a service manual.

As you know it is a voltage reference (which I didn't know 'till I
looked it up) and a replacement is available cheap.

I don't see any stock on it at Mouser or Digi-Key. Going through
Mouser's component picker, the TI (ex National) LM4041 may be a
replacement.

Can I safely test the electrolytic caps in-circuit with my DVOM? It
has a cap test function.

It may apply up to 9 V to the circuit, which the TTL parts won't like.
It probably won't give an accurate result in-circuit, no matter what
voltage it applies. If it costs $500 to get it wrong, I would take the
caps out of the circuit.

If you unsolder one lead of the cap and test it that way, the test
results should be reliable, and nothing should get damaged. If these
are the caps I am thinking of, though, it's hard to unsolder and remove
just one lead from the board - you may have to unsolder both leads and
remove it entirely.

Matt Roberds