17PW26 etc.!

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  • tom66
    EVs Rule
    • Apr 2011
    • 32560
    • UK

    #1

    17PW26 etc.!

    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!
    Last edited by tom66; 10-13-2011, 04:30 PM.
    Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
    For service manual, schematic, boardview (board view), datasheet, cad - use our search.
  • abdekader
    Senior Member
    • Jul 2014
    • 73
    • Turkey

    #2
    Re: 17PW26 etc.!

    thank you tom , i want the same this for 17pw25-4 please
    Electronic Engineer from Syria,Aleppo

    Comment

    • Clydeuk
      Senior Member
      • Jan 2012
      • 193

      #3
      Re: 17PW26 etc.!

      I've got a problem with one of these myself, using the 17PW26-1 PSU. There is a fault on the main board i.e. U114 flash i.c was corrupted, I have replaced the i.c but don't have the software for it so no DVB operation. However I don't know for sure but it may have been caused by the PSU, which is quite noisy in operation (like a hissing). I replaced a few capacitors, the remainder check fine for ESR and none are visibly bulging. When the PFC is in operation I'm only reading 375v across the big capacitor (sorry don't remember it's location but you know what I mean), and this coincides with the hissing noise. The set functions on analogue inputs (SCART etc.) however when I put it to standby the blue LED starts to flash and the only way to get it back on is disconnect the mains then reconnect.

      I'm unsure if my DVB fault is the cause of this or if it's the Power supply, the PFC output seems a bit low.

      Comment

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