[Coco] Seeking "F" / 285 / 26-3003 board Service Manual

Rogelio Perea os9dude at gmail.com
Mon Feb 19 18:01:09 EST 2018

Have been unlucky on line, only found Sams Computerfacts for the 26-3002
CoCo but nothing on the last incarnation of the CoCo 1.

This comes from a need to recalibrate/repair both my F board 64k CoCo and
TDP-100 - both are showing incorrect artifact colors on screen, for testing
purposes I am using Canyon Climber and checking on a CoCo 2 the first
screen comes up either as blue or orange mountaions upon each RESET, on the
F Board and TDP I see either magenta or green... playable but weird.

I know some F boards were fitted with a last minute fix by the VDG & Video
Mixer area with a resistor and something else inside a plastic tube,
soldered as an afterthought. My F board has that fix but the TDP does not.
All I've seen online is that Tandy provided that fix for some CoCo boards
that didn't display proper artifacts due to a weak video signal, not much
more info than that.

Any hints will be greatly appreciated. A lead to a service manual will be
even more GREATLY appreciated :-)

-- RP

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