Defeated by a Commodore 1950 Monitor

tony duell ard at
Tue Dec 2 13:50:55 CST 2014

> > Do you have a URL for this manual? I might give it a look and see if I can deduce anything.
> I found it here:
> I'll appreciate any insight you might offer, because I'm not very good at making sense of monitor circuitry yet. 
> My first suspect is IC401, followed by possibly IC402 or IC553.

OK, got it... What a confusing manual. It's roughly what I would expect a service manual to be
(schematics, parts lists, some faultfinding info) but it is not well organised... Perhaps I am spoilt
by HP and Barco manuals :-)

> You're right: It's an AOC CM314. I'll try calling AOC shortly on the slim chance that some old-timer might have a 
> dusty pile of documentation in his or her office. If not, one of the notable surplus dealers on our list has 
> contacted me about possibly supplying a working monitor. Finally, there's a 1950 on eBay, but I'll look for 
> cheaper options first.

AOC is 'Admiral of China' IIRC. I remember reading about US-made Admiral radios and TVs from the 
1950s. I guess this is a far eastern company that got the name.

To me IC401 looks like a sync processor/oscillator. IC402 looks like the vertical output stage.
I think pin 2 of IC402 is the output, pin 4 may well be the drive input (maybe a ramp voltage
here? D404 and C410 may well be that boost circuit I mentioned and are worth checking first.
Maybe then change IC402 if you can get one. 


Mark J. Blair, NF6X <nf6x at>

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