Re: AppleColor Composite schematic?

[Michael J. Mahon <mjmahon@aol.com>]

D Finnigan <dog_cow@macgui.com> wrote:
> Anyone have the schematic for the CRT controller for the AppleColor
> Composite display (NOT the IIgs)? Someone on AppleFritter seems to have a
> display where there is no green. I think it might be from a failed
> transistor.

Very likely--or just an open resistor, bad connection, or any of a number
of failures in the green channel. 

Since the three channels are virtually identical following chroma
demodulation, some signal tracing would quickly reveal where the green
signal is getting lost--or if it's the voltages on the green gun of the
CRT. 

For example, swapping red and green connections, or even bridging them with
a capacitor, could identify the point in the circuit where the signal is
lost. 

(Sorry I don't have a schematic at hand.)

-michael - NadaNet 3.1 and AppleCrate II: http://home.comcast.net/~mjmahon