[Coco] CoCo 1 colors off

[Luis Antoniosi (CoCoDemus)]

There are 4 trimmers to regulate on a coco1.

The first is the color burst variable capacitor next to the 6809. I use to
make a mark using a cd marker to  put it back to the positon.

The other is the 100 ohms  variable resistor close to the 1372. Its a black
round single turn resistor. If none works then you need a plastic
screwdriver to turn the 2 small trimmers inside the RF box. don't use metal
screwdriver as you act as an antenna.

Take care as they are very delicate and old. Don't much pressure on them.

If none of these work, then you must check either the 1372 or the VDG6847
itself. Also check the color lines from 6847 to the 1372 and a 100uF
electrolyct caps on the RF line.


On Fri, Nov 15, 2013 at 10:39 PM, Rogelio Perea <os9dude at gmail.com> wrote:

> It is NTSC using the Color Bars program provided in the CoCo User Manual,
> using a standard TV as a monitor and indeed no matter how the
> hue/tint/brightness controls are adjusted the noted colors are not being
> displayed correctly - used the TV with an MC-10 with correct output, it is
> the CoCo 1 (26-3001 rev D).
>
> Found the Sams Photofacts for the next model (26-3002), the docs for board
> E are close enough to provide a guide on what to check where, maybe some
> adjustment to a clock signal that could be creating these off-hue colors on
> screen.
>
>
> -- RP
>
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> Coco at maltedmedia.com
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>



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