On Fri, 5 Jul 2002 00:51:30 -0500, "Gregg Woodcock" <woodcock@sisna.com> wrote:
>Now if you are still blowing breakers, remove the connectors for the "HORIZ"
>and "VERT" heat-sunk transistors, and retest for no more than 15 seconds or
>so.
>If you do this too long, you will burn up R118-119/218-219. You have much
>longer before this happens if you upgraded them to 5W as advised earlier
>(but
>the 5W will still burn up and torch the PCB, too so don't get carried away).
>Leave power on until breakers blow or until you see R118-119/218-219
>begin to smoke/glow. When this happens, CUT POWER IMMEDIATELY!
>The breakers should NOT blow and you should get a tiny (1" square) picture
>(but don't bother watching for a picture;WATCH THE RESISTORS!)
There are better ways of testing the monitor than frying a couple of resistors.
Cinematronics highly recommends against this practice.
http://www.stormaster.com/Spies/arcade/schematics/cine/serv17.tiff
John Robertson's idea of unplugging the yoke (leave the HORZ and VERT
transistors plugged in), and using a light bulb to determine what axis is
blowing breakers is a much better idea.
>Your monitor should now work at least so far as popping the breakers goes.
>If your picture looks bad, try swapping your DAC-80 chips (IC-101/201).
>If the badness moves to the other axis, that DAC is bad. If not, you may
>also have a bad LF13331 which I have heard a lot about but have not yet
>found ever to be bad.
In the older monitors I've repaired, death of the LF13331 is the number one
reason the monitor does not work.
There's a *required* update that all the older monitors should have installed.
It's single diode that prevents the LF13331 from being back driven if the +/-
power supplies do not startup or shutdown at the same time. The newer monitors
have this diode already installed.
http://www.stormaster.com/Spies/arcade/schematics/cine/serv18.tiff
-Zonn
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Received on Sat Jul 6 22:46:19 2002
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