Star Tech Journal

Inter1nittent Video Proble1n
SOLUTION
I shut off the game and removed the monitor.
After upending it on the bench, a close look
revealed the problem: the base lead of the tran-
sistor socket had a cold solder joint where it
joined the main p.c. board. I could clearly see a
dark ring around the socket leg. I discharged
everything, plugged in the soldering iron, and
CAUSE
A lot of games out there use this monitor. Its
design says if transistor Q352 does not get a
signal, it shuts off the heater voltage and the
high voltage. Toe monitor as a whole is still
electrically hot, however, because a loss of
flyback-transformer action will not affect the B+
voltage (unless the flyback shorts out, in which
case it will blow the fuse).
__ .,. _____ _
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Rgure 1
sweated the joint. After remounting the monitor,
I plugged in all the cables and turned on the
game. This time the picture came on and stayed
there, no matter how much vibration we gave it.
It passed the acid test that night when we took
it back to the arcades; it came on fine and has
performed beautifully ever since.
*
Rgure2
If you have any manuals for this monitor, check
them to see if Q352 is labeled as such. Atari's
first printing of their manual for it, TM-283, left
out the reference number on the schematic.
Write in Q352 above the transistor if it is miss-
ing.