RCA LED55C55R12 No Power/Standby

[philtvman]

Not getting and power/standby light at all with this one. 5V standby is showing 4.94. All 5 volt lines are showing 4.94 and 12 volt lines are showing 12.5. The ON/OFF line is about 4.5.

I thought I found a shorted voltage regulator on the main board. When I took it off the board to remeasure, it looked fine. The short is still showing up between just the bare solder pads. Getting short between UW1 and UW2 in the picture attached. Is this normal for some of these regulators? Where should I go from there?

There are literally no main boards anywhere for this model unfortunately.

[philtvman]

Re: RCA LED55C55R12 No Power/Standby

Picture of main board voltage regulator.

[attainteddragon]

Re: RCA LED55C55R12 No Power/Standby

check the ceramic caps for shorts that match the pins the ones that you currently see shorted.
looks like the pair the the right of the regulator.
remove from circuit, retest the caps and the pcb to see if the short has gone.

[budm]

Re: RCA LED55C55R12 No Power/Standby

So what is the resistance reading on that 'Shorted circuit'? <1 Ohm?
What is the P/N of that regulator?

[philtvman]

Re: RCA LED55C55R12 No Power/Standby

check the ceramic caps for shorts that match the pins the ones that you currently see shorted.
looks like the pair the the right of the regulator.
remove from circuit, retest the caps and the pcb to see if the short has gone.

Removed the pair to the right, but short is still there.

The resistance between the shorted circuit leads moves around between 0.7-1.0 ohm. The part number for that regulator is LD1117AC 33AQQLTT.

[dskall]

Re: RCA LED55C55R12 No Power/Standby

If you have external power supply you can inject 3.3v current limited and check for component getting hot.

[philtvman]

If you have external power supply you can inject 3.3v current limited and check for component getting hot.

Don't have an external power supply on hand.