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Re: AppleColor Composite schematic?

Subject: Re: AppleColor Composite schematic?
From: retrogear <larrygr510@gmail.com>
Date: Wed, 20 Mar 2013 14:52:13 -0700 (PDT)
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In-reply-to: <dog_cow-1363635396@macgui.com>
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On Monday, March 18, 2013 2:36:38 PM UTC-5, D Finnigan 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. -- ]DF$ Apple II Book: http://macgui.com/newa2guide/ Usenet: http://macgui.com/usenet/ <-- get posts by email! Apple II Web & Blog hosting: http://a2hq.com/

most rgb displays of that vintage had an output transistor for each color channel probably with a heatsink attached. with a voltmeter, measure the voltage on the collector of each which would be the center pin or the metal tab on top. if one voltage is significantly higher than the other two then good possibility transistor is bad. if one voltage significantly lower than the others then more likely resistor, solder connection or (sigh) the crt itself.

Follow-Ups:
- Re: AppleColor Composite schematic?
  - From: "Michael J. Mahon" <mjmahon@aol.com>

References:
- AppleColor Composite schematic?
  - From: D Finnigan <dog_cow@macgui.com>

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