Re: My 7912ad had been dropped before I got it

Windsor Chan


Thanks for the kind words.

An update as how it's going; the horizontal sweep of the write section
has signs of life, as does the vertical section up to point at the out
put of the delay line. Beyond that point I'm not sure. In the read
section there good horizontal sweeping but vertical sweeping is
absent. There is a bad tant cap? in that section along with a burnt
resistor in series with it. I got a bit of advice as to disconect the
HV. I've pulled the end cap from the write gun. However I hope it
was not too late because I've powered up the unit before getting that
advice. Regarding the diode array, how suceptable to damage is it?

In any case it is a very interesting piece of hardware to work on,
very high performance, lots of tweaks perhaps due to the fact that it
is a very early model, serial number b010131.

The reason I ask about bypassing some of the digital circuitry is
multifold. First some of the boards have missing chips. Perhaps
reserved for future expansion or a hanger queen? Two I don't have
IEEE 488 interface on my computer. Third the impact looks nasty, did
the CRT survive? why not try to determine if the CRT is still good.
Last who could pass up a chance to examine and scope out the circuits?
The digital waveforms are rather sterile, while the analog waveforms
are interesting :)


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