Hi macafly,
Base of Q413 is the switch for this transistor to go complete cycle through the emitter and collector. Trace this line. If goes to the main board then you've a problem in its circuitry. Check also the 5v supply from the power supply going to your main board... t-con board control the picture of the screen which the command from main board.
Jdvillanueva
This could be the power supply failing with the power to the T-CON board. You can get a service manual from;
http://www.nodevice.com/manual/Sharp/page59.html
I presume you have check the capacitors.
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nothing obvious with the caps. pg e-3 says to check pins 1-5 for 5 v on cp2804. I've searched high and low and cannot find cp2804. at cp2802 pins 1-4 show 1.55v and pin 5 0.00v. Another note, This is the later "A" unit, and I have both service manuals. The "A" manual schematic shows 12v for pins 1-4. I don't understand the circuits, but it seems Q419 controls Q413 and J20 on IC2801 controls Q419.
I don't know the jargon, but what is the T-Con board? the digital pcb?
Thanks, Mark
pg e-3 of the service manual says to check pins 1-5 for 5 v on cp2804. I've searched high and low and cannot find cp2804. at cp2802 pins 1-4 show 1.55v and pin 5, 0.00v. Another note, This is the later "A" unit, and I have both service manuals. The "A" manual schematic shows 12v for pins 1-4. I don't understand the circuits, but it seems Q419 controls Q413 and J20 on IC2801 controls Q419. Thanks, Mark
I think the T-Con board is OK, because, if I short the emitter/collector of Q413, I get a picture.
I'm not sure where to check next. The voltages don't check out for Q419, or from IC2801. If I'm reading the schematic correctly, IC2801-J20 is the control voltage for Q419, which is the control for Q413.
Like I said before, I love to tinker, and know just enough to be dangerous, but need some help, so I don't just waste a lot of money on parts I don't need.
Thanks, Mark
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