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Repeat - Pioneer TV update/help

Discussion in 'Electronic Repair' started by Golf, Aug 5, 2007.

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  1. Golf

    Golf Guest

    Ok, here we go - with the B+ adjusted dead on 135V, I re-
    installed the power board. As soon as I plugged in the set, the
    clicked, and then nothing. Last post I told you all three tubes were
    lit, with faint raster. I unplugged the 8 pin socket that appears to
    come from the convergence board to the PB. Plugged set in and it
    powered up with 3 nice bright horizontal retrace lines - red, green,
    and blue (convergence drifted?) across center of screen. The lines
    were not real clean, but bright enough for normal raster I would
    suspect if the vertical was working. I didn't bother adjusting
    anything. Unplugged power cord, plugged this 8 pin socket back in and
    plugged set back in. Hit power button, relays clicked (saw green
    light on front panel), then shut down.
    I did have the set powered up with this 8 pin connected once,
    and got a picture, although it was very dark and grainy. I couldn't
    reproduce this again, and didn't get a look at the proportion of the
    raster looking at the tubes.
    Now concerning the 8 pin socket and plug - the socket at the
    power board has the following id's for each pin - -25, gnd, +25, PD,
    HV para, P key, V ret, V in . Best I can see all these terminate on
    the convergence board. There is a 4 pin plug on the convergence board
    that have these 4 pins (-25, gnd, +25, PD). I got so focused on
    checking solder joints on the covergence board, I never checked the
    damn voltages at this plug before I left my buddy's house.
    I am suspecting the PS may be fine, and the problem may be on
    the convergence board (yeah I better check the -25, and +25 supply).
    will do this next trip for sure. I hope this info clues you onto a
    probable cause here. Until then I will check discreet components on
    the convergence board since I brought this home with me, and find out
    what the two big IC's with massive heat sinks function are. Is one
    vertical IC, and other convergence? I've always seen 3 convergence
    IC"s in big screens, but again I haven't been doing this for very
    Thank you once again for your help.

    I have researched and found info on the STK4277SL (pincusion). I don't
    know if it's bad, but don't know how to test except substitution. I
    don't have the friggin schematic (another problem), but since the
    -25/+25 voltages from the power supply tie to this IC, and a
    malfunction of vertical may be causing the set to go into shut down,
    would it be feasable to try replacing the IC based off the info I have
    given? Thanks all for any suggestions.
  2. I'm no expert on big screens, but I don't think a convergence amp bad
    (that's what the 4277 is) would normally cause a shutdown problem.

    Mark Z.
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