Re: Kaypro II Video Problem



One thing that you need to do is turn the brightness up and the contrast down so you can see the "raster", even where it's black.

This is really a tv (monitor) repair problem, and I'd really advise you to seek help from someone familiar with TV or monitor repair. As monitors go, this one is VERY, VERY simple, the entire circuit of interest probably does not have 20 components in it. Doing anything with the deflection yoke was probably a mistake.


Tarkin wrote:
Thanks all,
              This info helps me to narrow down the possible cause(es)
and potential solutions. I cruised through other posts and found out
about the excellent (Kaypro) pdf at bitsavers.org - my Dealers'
Manual is nothing more than a stripped down version.
               Oddly enough, the manual instructs one to loosen the
neck clamp, reach in, and twist the yoke to square the display!
<NOTICE: What I describe next is my personal experience. Do not
attempt unless you understand there is a risk of *electrocution* and
*death* >
               Reading that and having had previous HV experience,
I did try and adjust the yoke, and I already mentioned adjusting the
deflectors....I caught a poke off the flyback, 30kV is a tickle
compared to my ~60kV homemade Jacob's Ladder. The most
dangerous items on the video side of the Kaypro II:
CRT ::
 Treat it like a large capacitor. The amperage is LETHAL.
Brightness Pot ::
 12V hot, and ground all around Use caution.
Yoke windings & Horiz. Width    ::
 Both have abundant RF energy; thus RF burns are
a possiblity. Use a plastic tool when adjusting the H. Width, and
avoid grabbing the deflection coils directly....they get real warm
real quick.
The Flyback Xformer ::
 There's an exposed metal bracket that seems either to carry or
induct the 30kV potential....I brushed it and lived, your mileage may
vary....

Sorry for the wordy post, but I'm trying to document this process as
I go...I googled "kaypro monitor repair" and waded through 26
pages of dead ends.....I'm hoping to save the next guy some the
hassle.

Thanks again for your insights. Testing begins sometime this
weekend, and I'll post the results.


--Tarkin

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