These Vestel PSUs are the spawn of the devil. I have three and NONE of them work properly.
Also go under the name of 17PW22, 17PW15, but they are all very similar.
Some things to look out for:
Dead standby Main filter cap measures good (~320V?) If so check diode D823 next to stby trafo. Can go s/c both ways 0.001V. Measures 0.52V good. Probably silicon. No filter cap voltage? Check fuse F800, PFC fet Q803, PFC diode D824, and bridge rect D800. Check stby controller IC806 and caps C801, C892. Check IC829 78L05. Check IC825 dual schottky rectifier (on back of board, looks like a DPAK.)
Standby but no run power Replacing C877/C878 (large poly caps near big trafo) is always a good idea. Also try replacing C801, C892 near standby controller (these actually filter some kind of run signal, for some reason they are over here.) Check IC807 (big DIP next to heatsink) supply and shutdown pin. Any ticking/clicking sound? Check for shorted FETs along secondary heatsink and try running without load. Check D845/D846 for shorts. Check power is getting to SG2525A if not check R897. Check SMD R817, R818, R819 on back of board, each should measure 620k.
Flashing LED Check stby rails (5V & 3.3V) and replace 78L05, and two 4700u 6.3V caps C857, C818.
Powers up but switches off after several mins, or backlight flickers Check PFC bus is at ~395V if not check PFC ctrl and IC828 the freestanding TO220 LM317T, should have 1.25V between adj/out. Also monitor 24V during flickering.
Intermittent startup Caps C835, C834, C840, C826 and PFC circuit see above.
Low rails Check optos and secondary caps. Check PFC. Check for s/c on any rails.
Doesn't tune into many Freeview signals, weak or blocky picture, weak analogue signal Check R878 and D821. D821 is a 33V zener and with resistor, generates Tuner/IF bias voltage of +33V. Leaky/open zener causes too high or too low 33V which will cause picture problems.
These are the hints I have gathered so far on these power supplies, I hope they help someone else!
Also go under the name of 17PW22, 17PW15, but they are all very similar.
Some things to look out for:
Dead standby Main filter cap measures good (~320V?) If so check diode D823 next to stby trafo. Can go s/c both ways 0.001V. Measures 0.52V good. Probably silicon. No filter cap voltage? Check fuse F800, PFC fet Q803, PFC diode D824, and bridge rect D800. Check stby controller IC806 and caps C801, C892. Check IC829 78L05. Check IC825 dual schottky rectifier (on back of board, looks like a DPAK.)
Standby but no run power Replacing C877/C878 (large poly caps near big trafo) is always a good idea. Also try replacing C801, C892 near standby controller (these actually filter some kind of run signal, for some reason they are over here.) Check IC807 (big DIP next to heatsink) supply and shutdown pin. Any ticking/clicking sound? Check for shorted FETs along secondary heatsink and try running without load. Check D845/D846 for shorts. Check power is getting to SG2525A if not check R897. Check SMD R817, R818, R819 on back of board, each should measure 620k.
Flashing LED Check stby rails (5V & 3.3V) and replace 78L05, and two 4700u 6.3V caps C857, C818.
Powers up but switches off after several mins, or backlight flickers Check PFC bus is at ~395V if not check PFC ctrl and IC828 the freestanding TO220 LM317T, should have 1.25V between adj/out. Also monitor 24V during flickering.
Intermittent startup Caps C835, C834, C840, C826 and PFC circuit see above.
Low rails Check optos and secondary caps. Check PFC. Check for s/c on any rails.
Doesn't tune into many Freeview signals, weak or blocky picture, weak analogue signal Check R878 and D821. D821 is a 33V zener and with resistor, generates Tuner/IF bias voltage of +33V. Leaky/open zener causes too high or too low 33V which will cause picture problems.
These are the hints I have gathered so far on these power supplies, I hope they help someone else!
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