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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Samsung Model SPT-521J 52" Projection - Pulsating Pix
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 deflection 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. -- Posted via Mailgate.ORG Server - http://www.Mailgate.ORG |
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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. "Ron Novini" wrote in message news:9fe01f6b2b0da4a1a225a486adefe2fa.123933@mygat e.mailgate.org... 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 deflection 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. -- Posted via Mailgate.ORG Server - http://www.Mailgate.ORG |
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