RCA LED52B45RQ wont stay on

[jasonbay13]

i have the same tv and power supply board as in the forum thread below, though i have different symptoms than anywhere else i've looked and cannot find a schematic or anything else to help me.

the problem is that the red light comes on and i get 5v at +5vsb but when i press the power button the red light goes out for half a second and the +5vsb drops to 2v or so (almost too quick for my meter to read a drop at all) and the +12v shows 11v or so for a split second and +5v shows 4-5v for a split second.
This is repeatable as many times as you want to press the power button, except!!! i did get it to turn on twice.

would this be a power supply problem or a mainboard issue? sounds to me like something is shorting out but if so, then how did it come on? checked esr of +5v cap and checked good as new no other caps are visibly problematic either.

seems to me there is a hot spot on the board around the ic/diode by C48 (discoloration of the board and what appeared to be cracked solder joints i attempted to reflow with no change in behavior).





https://www.badcaps.net/forum/showthread.php?t=71141

[R_J]

Re: RCA LED52B45RQ wont stay on

Post pictures of YOUR board. It might be obvious whats wrong when someone sees your board. Did you check D18A and D18B ?

[jasonbay13]

Re: RCA LED52B45RQ wont stay on

i got it working. i touched up a few more solder joints and changed out c14 (33ohms) and c5 (2 ohms).

can anyone tell me why c14 is important to have a low esr?

[budm]

Re: RCA LED52B45RQ wont stay on

C14 is the startup/running cap for the standby power supply section, when it is bad it will cause the power supply to start/stop so that is why you see the 5VSTBY goes up and down with heavy load.
What is the value of the cap? It is usually around 47 ~ 56uF 50V, you can get away using good quality 105c general purpose cap.

[jasonbay13]

Re: RCA LED52B45RQ wont stay on

ok, so.... the tv will come on sometimes. and now seems to have a similar problem as the thread i linked in the first post.

plug it in and the red light comes on. press the power button and the tv turns on. anywhere from 0 seconds to 20 minutes the tv will shut off. 5vstb stays at 5v and on/off stays at 4.65v (after tv has shut off).

i've tried forcing on\off and backlight without luck. power supply shuts down.

however, if i leave either the backlight on/off cable disconnected or the led connectors disconnected it stays on, just no backlight.


in conclusion: i either have a bad power supply board or bad backlight (which i've read is a problem with this tv).

[jasonbay13]

Re: RCA LED52B45RQ wont stay on

woo wee!

it exploded in my face!
i was plugging it in to try and read some voltages and q10 exploded.
unfortunately for me there are no replacements for this board and i have no idea what that ic was, or if the power supply board was even at fault though it and the main board both had bad caps.

i guess this one goes in the dumpster unless anyone wants parts.

[nomoresonys]

Re: RCA LED52B45RQ wont stay on

Being an rca, it probably should be trashed, ran across this ad, don't know anything about them tho: https://www.wsrepairs.com/product-pa...rca-led52b45rq