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Samsung Model SPT-521J 52" Projection - Pulsating Pix


Ron Novini

Jan 1, 1970
Working on a Samsung Compac Theater Model SPT-521J 52" Projection TV.
After warming up for about 5 minutes, the picture would begin to
pulsate from regular overall bright to less bright every few seconds.
It appeared as if it would change picture mode from standard to mild.
This is very annoying to the customer. Upon examination of the
board, a burned section (appears if a tiny fire occurred) was located
near the 210 volt plug near the flyback. Closer examination revealed
that the trace from the 210 volt line was connected originally
to two resistors (R493 and R492,100k,1/4 w) in series to ground. This
connection was burned to the point of no connection to the 210volt line.
After replacement and reconnection of the resistors to the 210 volt line
and further resoldering the heater circuitry from T401 (R441,R446 with
initial bad solder and cracks), I re-installed the board. Operation of
the tv again did not cure the pulsating problem. Sounds like a very
rare situation. Any help would be appreciated. Thanks ahead, Ron.


Jan 1, 1970
Check each CRT for leakage, esp some getting onto the CRT Drive Boards. Seen
a few in which the Red CRT PWB tends to aggravate all of the others.