1 Dec
2014
1 Dec
'14
5:22 p.m.
On Dec 1, 2014, at 16:30 , Zane Healy <healyzh at
aracnet.com> wrote:
Are you just driving it off the built in VGA, or do you have a VGA card in it?
Just the built-in VGA. As I understand it, plain old 31 kHz monitors will work with the
flicker-fixer turned on, right?
On Dec 1, 2014, at 16:42 , Geoff Oltmans <oltmansg
at gmail.com> wrote:
Well, if you do replace it with another CRT monitor, don't toss the 1950! Monitors
that sync that low are few and far between, and although the Commodore monitor ain't
the best, it is a brand match and will work with the A3000 as well as the A1200 and A4000
in all unflicker-fixed modes.
Yeah, I'd love to use the brand-matched monitor even though it's not the greatest
monitor. Maybe another parts-donor will come along, and I can build a working monitor out
of the pair?
An oscilloscope would go a long way to helping with
the repair.
It sure would, if I knew what any of the pins on the chip were supposed to be doing!
It's just a 20-pin DIP with no explanation of what the chip's function is in the
circuit, other than what I can infer from circuit topology.
I really don't enjoy working on monitors like this one, or else I might poke around
some more... lots of pointy high-voltage stuff, and very poor circuit accessibility
without reducing it to a pile of loose boards and a tangle of cables next to a naked CRT
rocking on the bench. Pretty much the whole thing needs to be taken to pieces to get to
the solder side of the main board. Grr!
If I could identify and procure that IC, and perhaps a few others in the vertical drive
circuit, I'd happily tear it all apart, swap the chips, and cross my fingers. Hmm,
maybe I should expend some more effort to try to find out if the OEM is still around (said
to be a company called AOC, in Milpitas, CA), and whether anybody there might be able to
identify the IC in question? I think it's a long shot, but maybe I'll get lucky.
--
Mark J. Blair, NF6X <nf6x at nf6x.net>
http://www.nf6x.net/