Tempest DAC

OK, so I found 5 DAC312s at a local distributor and after
replacing one, it wasn't the problem. First the XREF
was mysteriously being held low so I jumpered
in the YREF voltage.

Then the YINV is being held low. It was getting
late, so I clipped the harness jumper to get the
signal at least going through the other section.
Letting it through the proper section railed it.
I don't know if one of the LF13201s is shorted
internally, or what.
Has anyone tried replacing it with a 4066?

I finally got a signal all the way through to the
outputs and the monitor came to life but it is
one wacky picture. It's not the monitor, I tried
a good board already.

Has anyone marked up the schematics with expected
waveforms at each stage? If not, I guess I'll have to try
that with my good board.

--
Brendan Keith
brendan.keith@wilcom.com