Sharp LC-32SB23U Power-on issues

[tristantech]

I pulled a Sharp LC-32SB23U flatscreen out of somebody's trash, took it home, and became surprised to find it completely functional --for a few days. Since last night, the TV will not power up. The green power LED illuminates and several relays can be heard; they click on and back off several times over the course of a minute. After that, the power and OPC LEDs blink once together followed by two flashes of the power LED alone. Based on my research, this indicates some form of PSU issue. Opening the TV and poking around caused it to power up fine on two occasions so I am convinced that the bulbs and other hardware are fine except some intermittent bug or bad contact, perhaps. I have done many cycles of removing the power cord and pushing various key combinations. I should also say that I performed a software update the day of the failure, but the TV worked fine after that for a while.

Could somebody tell me the meaning of this LED code or provide a repair trick? I can also buy a new power supply board if needed.

[tristantech]

Re: Sharp LC-32SB23U Power-on issues

I looked into it further and learned that the blink code indicates a problem with the 13V supply. However, I can measure 13v present on the PS board output. What could be wrong?

[R_J]

Re: Sharp LC-32SB23U Power-on issues

From the manual:
Power led flashes twice, opc led flashes twice
EU_POW
Main 3.3V failure
Flashes twice

DET_POW3 (pin 36): Abnormal (L). Main power 3.3V is not
applied.
If error is detected during operation, error standby is activated
by polling.

This is what you get in the manuals these days.
Looks like unreg. 13V goes to ic9641 (mp1415c) that gives 3.3 volts out on pin3

[dick_barton]

Re: Sharp LC-32SB23U Power-on issues

IC9602 (MP1415C) regulates the incoming unregulated 13V down to a regulated 3.3V so would be worth checking out.

Edit
RJ is quite correct and it's IC9641 which needs to be checked out.