RCA 55" LED55G55R120Q, led driver comes up and shuts right down

[football0062]

have a LED55G55R120Q the LED driver is built into the power supply, uses 2 sets of 6 row LED strips, 9 leds per strip. so 54 leds per channel. running at 179volts peak. the issue is when i trigger the backlight on, even manually by supplying 4v to the BLon and Adj the leds light and fall right on its face.

replaced with an ebay "supposed working board"
tested all LEDs(working) tested by running to a board from another set i had using a 174volt source.
replaced main board(reason i tried this was because while messing around with the power supply i can get the led driver to stay on if i apply 4v to the adj and bLon rapidly i will get lucky and it will just stay on. new board made no difference.


board is a RE46HQ1640

[dick_barton]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

It may just be the camera angle but one of the solder joints on the led output connector looks bad. Circled red.

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

thats just leftover solder from when i connected both grounds to eachother, made no difference, still just blinked on and right back off

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

also i have replaced these caps, board is full of the cheap capXon and Aishi polarized caps

[dick_barton]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

So you can verify that all the leds work by connecting them to another supply. If that's the case then you may have a Led driver fault. What IC controls the LEDS?

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

there is no led controller, its all zener diodes, resistors and caps.

and yes the leds work perfectly every one lit and stays lit using a board from another set (part number is 890-pf0-5501)

also i just swapped the driver ICs on the primary side, made no difference, also if i short the photocoupler in the picture on the primary side it does the same thing, leds light up and falls. it actually does this in 2 quick pulses, either way i turn it on, with main board or by shorting the photocoupler

[dick_barton]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

Looks like it going to be a hard slog of checking each and every component with your meter to see if you can spot a problem. Without a schematic I can't suggest any other option.

[budm]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

OOPS! wrong board wrong thread!

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

ok so i just noticed something here, on my primary im only getting 160V DC usually i at least get 168VDC in a standby state, but i am switching this power supply on using the PSon making it high with a 4v input. when i turn the leds on it drops to 150s. on this power supply doesnt the transformer L102 which i have circled, up the voltage to 350-380 range? main cap is rated at 450V.

[budm]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

The inductor is for the PFC Voltage booster, so when PS-ON is present the DCV between the two legs of the main cap should be 380~400VDC range.

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

yea and its 160v, think that is where my problem is

[budm]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

U101 is the PFC Controller IC.

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

ok so this is what happens, i started from the beginning to see what was going on.

using main board
-turn power on, 350v at main cap, leds flash, then voltage drops to 158v on main cap.
-will not come back up unless i unplug and plug it back in
manually applying 4v to ps on, then 4v to BLon
-cap stays at 350V the whole time 4v is supplied to pson
-when 4v is applied to BLon, leds flash. cannot get voltage back up without unplugging and plugging back in.

Now if i disconnect the LEDs from the power supply(i know bad idea) i get 228V output on my secondary and it stays constant. that doesnt add up either because there is only 54 leds. each would have to make up for 4.222....volts. i know there is no load though. thoughts?

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

ok so heres the update, the led driver still will not do anything more than power up those 2 sets off 54 leds for more than a hot second, but it will power on and stay on at 180v to 2 sets of 56leds each side of a strip i had laying around out of a samsung.

also i hooked the other power supply up(890-pf0-5501) that i was using to test the leds on this rca and it still lights every single led up. what the fockk pics attached

(the bar has 56 leds per half in series.)
(the strips have 9 leds in series with 6 strips per side in series, totaling 54 leds)

any thoughts as to what might be going on?

[football0062]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

**THE FIX**(i hope)

i loaded up a completely different set of leds and soldered the strips into series. 54 on one line and 56 on the other. ran perfect. so dropped one out and put in 1 set from the TV, worked perfectly, so i swapped to the other set in the tv and that side worked perfectly as well. so i put both sides together for the fun of it and bam! fired right up. only thing that changes was the crimping on the cables got cut off and stripped to bare wire. so soldered wires straight to board and its been running perfectly.... strange because i remember even checking resistance from the LED driver to the boards and they all looked fine in the beginning.

[Deaddog2017]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

Working on the same problem ,same set, LED55g55r120q. I get the quick flash with some vertical lines. Looks like PS goes into shutdown. Changed out PS but same problem. No voltage on LED + and - outputs from PS.
Do you know what the voltage should be?

[stuffinabox]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

same set close to same issue when i turn on takes a few minutes noted that the 6v on power supply comes up at 4 initially. thinking failing power circuit. some of the time i can power off and back on and come right up.

[ndriana]

Re: RCA 55" LED55G55R120Q, led driver comes up and shuts right down

So, in the, you have no clues why it didn't work, and why it did work?
I'm still on the part where why it doesn't work.