Troubleshooting a 5V Apple III

Mike Maginnis mmaginnis at
Sun Aug 22 14:05:54 CDT 2010

On 8/22/2010 12:19 PM, Richard wrote:
> In article<4C7160FF.4060009 at>,
>      Mike Maginnis<mmaginnis at>   writes:
>> Can anyone suggest a starting point for tracking this down?
> I'm not familiar with the Apple III schematics.  Does the motherboard
> include video?
> If so, then it sounds like everything's good but you have a bad video
> section.  I'd start looking at capacitors and if you have a high
> bandwidth scope it might be instructive to look at the video out to
> see if you're getting any sort of video timing at all (sync signals,
> etc.).

The motherboard has both composite and digital XRGB video outputs.  I've 
been working with a composite monitor, as I don't have a compatible RGB 
model.  Unfortunately, I don't have a scope or anything more advanced 
than a multimeter to troubleshoot with.

- Mike

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