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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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Repeat - Pioneer TV update/help
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 relays 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 power 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). I 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 long. 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
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Repeat - Pioneer TV update/help
"Golf" wrote in message ups.com... 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 relays 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 power 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). I 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 long. 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. 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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