Hi! If I have the 162 Volts To the regultor and no voltages off of T5545, doesnthat mean that IC7520 controller is bad or is ther something else in the supply circuit at fault. If I had a drawing I could maybe figure it out, but by the time I got a drawing charge a little labor I end up with the set. If anyone can give me an idea, thanks. Vince
Philips Magnavox Chassis 25F800
Jan 19, 2006
3 Replies
Usually, failed flyback transformer causes shorted HOT, which shuts down the supply. Could be other things, but shorted supply on the output side of transformer is quite common.
Check also standby supply. About 10-15 VDC ref. to hot ground on pin 1 or IC 7520. Sometimes open R 3510 = 33K or shorted Z 6510 = BZX79-C20.
Many of the Philips chassis, I cannot remember if it applied to the F8 as well but I seem to remember it on the B8 design, had a couple of I think 15K resistors in series that provided the initial startup for the smps ic. They were directly on the 168Vdc of the main filter capacitor.
More often than not if everything else checked ok, we would find one of those open for no apparant reason.
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