RCA LED32B30RQD backlight flashing

[gregvm]

Unit works, all inputs, except the backlight keeps flashing(about twice a second). Replaced all the elec. caps on the power board(#RS072S-4T06).
Hooked it up. Worked GREAT....for about 5 minutes....now back to the same flashing. Output voltage on 12 led pins is 62v unplugged from leds, 36v plugged in, with no apparent voltage fluctuation. Using a benchtop ps I connected 32v (highest it will go) to each group of six banks of led lights....each light up normally(dim, but no flashing) so I assume it's in the ps. I didn't change the MAIN elec. cap on the primary side, as I didn't have one on hand.

Any ideas? Regulator? MOSFET?

Thanks

Greg

[gregvm]

Re: RCA LED32B30RQD backlight flashing

Update: Here are pics of board highlighting the area of PSU that is in question....

[ben7]

Re: RCA LED32B30RQD backlight flashing

No pictures are showing.

What is the voltage drop across one LED? And how many LEDs are there in total?

Is there a backlight dimming pin? If so, check that to see if it is fluctuating. You might need a fast DMM or an oscilloscope to see it.

-Ben

[gregvm]

Re: RCA LED32B30RQD backlight flashing

Sorry, here are the pics......

[gregvm]

Re: RCA LED32B30RQD backlight flashing

Ttt

[ben7]

Re: RCA LED32B30RQD backlight flashing

Honestly, I'm not sure what could be wrong.

Have you tried checking any transistor or diodes?

You also might want to look for any cracked solder joints too.

I've checked on google and it seems that this is a common problem for this set.

My other thought could be that an LED is going bad. I've had LEDs fail intermittently, and they would flicker on and off (the LED junction would go open circuit, cool down, complete the circuit again, and then heat up and go open circuit ... repeat ...)

When using the TV's power supply to power the LEDs, are there any LEDs that are a dimmer than the others?

-Ben

[gregvm]

Re: RCA LED32B30RQD backlight flashing

Yeah, I re-wet most of the solder joints over the weekend.....still the same.

I found a psu for relatively cheap that I'll try, if it works, I'll post. If not it MUST be the leds(I haven't delved into the are of the set that the leds are at.....yet.....last resort. It has 6 pair of power wires going to them and if I supply bench voltage to any individual pair, I get constant leds in all zones of the display. I'm thinking that the leds all together are too much of a load for a weak component in the psu, and causes the oscillation. I'll see......

I'd just pitch the whole set, but I really liked the picture it had and with the built in dvd player, neatened up the spot where it was. Had low power consumption too, as it's on practically 24/7.

Thanks
Greg

[gregvm]

Re: RCA LED32B30RQD backlight flashing

UPDATE: Well swapped PSU and still exactly the same....got into the backlights......

Bottom strip has every other led out.....12 total, 6 don't light.

So...how do you test this strip? I don't have my camera right now to take pic, but the strip p/n's are: SHARP E227809 C HX-S 94V-0

also : F302Z19WCA054841A2 A

If I swap the strips, (there are 3) with each other,it still is the same flashing(but the same strip has six lights out), so it's THAT particular strip that has issues. It says "six series, 2 parallel" on the strip as well. There are 16 test points, but I can't seem to make sense of the schematic.

I'll post pics asap.

Thanks
Greg

[gregvm]

Re: RCA LED32B30RQD backlight flashing

Ok, after playing around with the test points I figured out that #10 led is bad.
Was just dim at first, now it's out altogether. All other 11 draw 12.4 to 15 ma, but that one only would draw .12 ma at first, now it's open.

Can I just replace one led? How are they fastened?

Thanks

Greg

[budm]

Re: RCA LED32B30RQD backlight flashing

I do not know what your LED strings are like, but you may be able to do this:
https://www.badcaps.net/forum/showthread.php?t=46403
But I am sure that the other LEDs may go out soon, you should the backlights level to as low as possible to extend the LEDs life.
https://www.badcaps.net/forum/showthread.php?t=46403

[gregvm]

Re: RCA LED32B30RQD backlight flashing(FIXED)

Update: Fixed......one led was open in series of six.....replaced with a white led....all is good....

Pretty bad when a .25 led takes out a whole tv set.......

Thanks for the help

Greg

[beto84]

Re: RCA LED32B30RQD backlight flashing

hello gregvm! hey I have the exact same problem, same tv model. I replaced the led strip that had only six of the bulbs functioning but it is till flickering. How did you test the bulbs individually? and how were you able to unfastened it and replace the one bulb?

[beto84]

Re: RCA LED32B30RQD backlight flashing

Greg you mention you replaced the led strip that had only six of the leds working. I don't get why that didn't fix the problem. Do the other bulb you replaced was on a different strip?

[beto84]

Re: RCA LED32B30RQD backlight flashing(FIXED)

Update: Fixed......one led was open in series of six.....replaced with a white led....all is good....

Pretty bad when a .25 led takes out a whole tv set.......

Thanks for the help

Greg

Hello gregvm! hey I have the exact same problem, same tv model. I replaced the led strip that had only six of the bulbs functioning but it is till flickering. How did you test the bulbs individually? and how were you able to unfastened it and replace the one bulb? Greg you mention you replaced the led strip that had only six of the leds working. I don't get why that didn't fix the problem. Do the other bulb you replaced was on a different strip?

I really appreciate any help. thanks

[Popeye2000]

Re: RCA LED32B30RQD backlight flashing

I had the same problem. I solved it much differently. First, the main cap on the board should have ~170v. There is a 12 pin connector for the LEDs, check the pin out, first check voltages on the top of the connectors. Should be about 30v. Remove the connector and check the voltage on the 12 pins. Should be about 60v (I got 61.4v). Make sure to check the pcb indications for which is positive and negative. The first four are positive, then two negative, then two positive then four negative.

If all is fine, check the pins in the connector to see if they are fully seated in the connector. I had the unit powered on and noticed that as I applied pressure differently the flickering would go away depending how pressure was applied. I reseated the pins in the connector by gently pushing on the pins with a jewelers screwdriver and everything has been working just fine.

Hope this helps.

[starbaja]

Re: RCA LED32B30RQD backlight flashing(FIXED)

Update: Fixed......one led was open in series of six.....replaced with a white led....all is good....

Pretty bad when a .25 led takes out a whole tv set.......

Thanks for the help

Greg

Hi Greg, I read all the procedures, I have the same TV same problem.
If I replaced all the power supply it will fix my flickering problem?

Albert Gonzalez

[taitsui]

Re: RCA LED32B30RQD backlight flashing

This is the common problem with this model of RCA TV, the problem is not defective LED strips, but the power supply.

You may purchase a power supply on the net, but you can't guaranty that it is a good one.

This is the trick to make this TV work:

On the power supply, locate the R410 100K resister, solder a 220K/0.125W resistor in parallel with it, this will race up the oscillation frequency of the back light power supply circuit & make the voltage stable.

It is not a proper service procedure, but it works for us.

[Electronic Handyman]

Re: RCA LED32B30RQD backlight flashing

This is just my opinion. I have been looking at the pics of the psu and I noticed a few back connections.I can bet that those boards have several bad soldering connections.If I had one of those sets for sure I'd solder all of the board that I can.Note that even so called new boards can and probably do have bad connections.From what I know RCA is famous for cheapy capacitors and bad soldering.
By the way changing the leds may have fixed the issues bec the load and voltages are a bit different so the PSU works with them.If you find bad leds you can bypass them also as long as it's not too many.

[niccapila]

Re: RCA LED32B30RQD backlight flashing

buona sera a tutti ! esiste uno schematic diagram per questo alimentatore ? ho cercato in rete ma non lo trovo.

[budm]

Re: RCA LED32B30RQD backlight flashing

https://www.badcaps.net/forum/showth...ght=RCA+LED%2A