Trying to make one HP 54501A out of two
 

Hello all,

I came across this in an old thread:
-----
I've bought an HP 54501A 100MHz digitizing oscilloscope, but it doesn't
work!

It seems to have a problem on the NON-VOLATILE RAM, so it doesn't pass the
self-tests.

Performing all the self-tests it gives 3 fails:

FAILED Protected non-volatile RAM TEST - 0000 0000 0000 0001
FAILED A/D TEST - 0000 0000 0111 1111
FAILED D/A TEST - 0000 0000 0000 1000

I think A/D and D/A fails depends on first fail, becouse CPU stores the
calibration information in this memory (this information comes from the
manuals).
-----

I have one with a similar problem (My D/A failure code is 000F) and I'd
like to know if anyone can interpret these codes. Also, is the above
author correct in the assumption that the A/D stages can fail as a
result of the NVRAM failure?

There is a Dallas clock ic in the scope that could be causing the first
problem.

I have two of these scopes. The other one does not start up at all. I
was hoping I could swap some parts around and make one good one. Can
anyone offer any suggestions or point me to some schematics?

The service manual on Agilent's web site does not go far beyond the
"motherboard bad, replace motherboard" point.

Thanks in advance.