[Coco] cm-8

[Neil Morrison]

(Almost) anything is possible, but always try the easy things first.
I don't think I have a service manual, but from your description I
would be looking at the driver system to the chip. It's also possible
you have a short in the deflection coils and that this is throwing
the system off.

Neil

----- Original Message ----- 
From: "Kevin Diggs" <kevdig at hypersurf.com>


> Hi,
>
> I replaced three of the caps using jumpers (the power supply filter
cap
> (c510),
> a capacitor in the voltage booster circuit (c513), and a coupling
cap
> for feedback
> to vert osc. (c509)). None helped. The DC voltage on the vert
driver
> output pin ((pin 6
> on I.C 601, the sync processor ic) is off:  reading about 6. Should
be
> 0.9. The DC
> voltage on the vert deflection ic input pin (4) is also wrong:
reading
> 3.2. Should
> be 0.8.
>
> The little picture of the vertical output says it should be 35v
p-p. I
> am getting
> about 22v p-p. The raster only covers the upper 2/3 or so off the
> screen. This makes
> me suspect the "voltage booster" in the vert. deflection ic?