Originally Posted by hopsing44
Hello AVS members:
Most likely, one of these regulators is for the 5 volt buss, the other for the 12 volt buss. Which is which I don't know yet.
If anyone does, look in there and see if it gives any clues to the identity for:Q2101 & Q2203.
There should be printing on the voltage reg. I say should because I once had a (overpriced) video processor that the manufacturer had sanded all the ICs to remove the numbers. I guess they didn't want anyone copying their proprietary design.
But, in your case, the reg might not be dead. In repairing a number of LCD TVs, I have found that part of the power supply is always hot, to power the IR remote circuitry, while another part is not hot until you switch the unit on. Do you hear a click or any indication that the unit is powering on?
I haven't followed all of what you have checked, but sometimes capacitors fail and change values, causing power supply issues. Any of them bulging?
Any fuses bad? Should be marked F1, F2, etc. on board. But Voltage regs do go bad, so that very well may be the problem. I would start by trying to get voltage readings. And I understand your hesitation about short circuiting with the probe. I've done that before, and it sucks.