Toshiba 32W3433DL. Backlight shuts off in Auto

[yohnsee]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

If it won't light up with the old one or with the new one, i would say it is backlight led issue.

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Yes, that's my worst fear, as I've seen videos of how to access the led stripes and that's nothing I want to do.
I will probably return the TV as is and try to sell the new PS board on ebay

Thanks!

[yohnsee]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

If you are lucky enough and find a tv with a matching broken screen for cheap, you should go for it. Because it is easier to change the whole metal chassis with the leds in it, than the component level rework.

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Yes, but I don't think Im going to be so lucky to find one compatible that's broken.
Maybe the leds are running more current but they used to work...I mean, with a fixed (non protected) power supply I think they would light up. What if I apply a resistor in series to the LED wire to lower the amperage? Will the PS stop detecting the overcurrent and let the LEDS work?

Thanks

[yohnsee]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

They will eventually fail. And I personally wouldn't mess with the current sensing, it is a safety set for a reason.
Or you can end up like this:
https://www.badcaps.net/forum/showpo...0&postcount=10
And who needs bad reputation? Let's say, you make this trick with the backlights, then after 2-3 months the customer comes back with the set burned or exploded. I may be exaggerating, but you get the idea.

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Yes Yohnsee. I totally agree on second thought...
Actually, I called the client telling him I would return his TV and the money he had already paid for the first repair, and as he was going to throw it away, I kept the set for 10€ extra. It's not a bad TV, with Wifi and ethernet, I will eventually try to open the screen and see if I get to the led strips to replace them
Thanks!

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Ok, big update on this subject
I ended up returning the TV to the owner at no cost for him, he said he would pitch it, so I paid him a small amount to keep it and try to repair it for myself.
I disassembled the full frame to get to the (suspect) LED strips. 2 strips of 11 LEDs each
I applied 38V to each of strip individually (24V DC transformer + 3S LiPo battery )
Strip 1: 9 LEDS light fully, then after 2 seconds 10th LED lights up, and then after 2 more seconds they all shur off (probably 10th LED, which took a while to start up, is pulling more current that the others and shut down my 24VCD PS). There still a 11th LED that never lit up. I marked led 10th as suspect and led 11th as FAIL. I geuss I would replace both
Strip 2: Very different behaviour. All the LEDs but one light up VERY VERY dim, hard to appreciate. One stays off all the time. My guess, as they are all in series, if I swap this LED everything will work again, right?

Ok then I watched some videos on how to replace individual LEDS on TV strips. Because I've seen the price for each LED and they run beyond $15 for each, seems too much to me. All the videos about replacing seem to use a rework station that's basically a controlled heated board (Jimmy.com). Have you guys obtained good results with old school tools? Can you share your method to replace individual LEDs?

Thank you!

[yohnsee]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Hello.
Happy to hear from your progress. First, if you want to change the individual LEDs only, you will need a controllable hot air station. Preferably with different nozzle sizes. Well, to get those pesky faulty leds off the board, you only need a soldering iron and a good amount of solder, that covers the whole LED chip with molten solder. You can try to get the good ones back with a very sharp soldering tip, but there are certain types that impossible to do this way. That's why you need hot air. After you kicked down the bad led, you need to clean the copper pads. This is done with flux and desoldering braid. You can tin the pads with very little amount of solder, but I personally prefer the solder paste for this job, as it contains solder and flux. Then position the led, apply heat, and ready. But NEVER apply heat directly to the led, as it degrades its life. I always make circles around it, heating up the copper and the solder, and then it nicely positions itself. I hope this helped, can go into further details if needed. Btw, the individual leds shouldn't cost so much. Or were you speaking about $15/strip?

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Thanks Yohnsee. Yes, $15 each strip, so $30 in total for this set. Replacing the individual LEDs seems much more fun (and cheaper)!

The only hot air "station" I do have is a portable butane soldering iron, which has a tip for hot air, not sure if this would work.

The back of the led strips seems pretty thick and mostly solid copper, so I was wondering if leaning the back of the LED strip onto the first part of the soldering iron may do the heating job from underneath like those heating boards. I don't want to melt a new led by accidentally applying too much hot air onto it.

I've already bought a bunch of replacement leds online (specific for this strip), awaiting for them to come

I've just jumpered the faulty led in the strip that would barely light up, and this makes all the other leds to fully light up, so I'll be good on that one swapping only one LED

Thanks!

[yohnsee]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Hi!
So about replacing individual leds. Cheaper? Yeah, sure. Fun? Maybe it will be, when you practiced it a few times. If you repair this set for someone else, you will see it is more time and energy efficient to replace the strips. 30 bucks is not much for a whole backlight. BUT if you have time, and you invest it into learning, then go ahead, change those faulty leds. You will get experience, what can not be measured in money.
Also, yesterday I ran into a third method I was not aware of yet. Someone repaired the backlight in a Vestel set the following way: they knocked off the faulty leds, cleaned the pads to be flat, then put on some kapton tape, and used these over the original pcb: https://www.ebay.com/itm/100X-3528-S...97.m4902.l9144
They scratched the paint on the original pcb, and connected it with 2 wires into the system. Not the most elegant way to do this, but fast. And there was no noticeable difference in light spread.
I mentioned the hot air station. It has the advantage, that you can control the heat and the airflow seperately. With the butane soldering iron, I am not sure.
Can you access the underside of the led strips? Or are they glued to the metal plate? With the metal plate, you won't have a chance to heat it up together from under, but if you seperated the pcb from the metal plate, then there may be a way.

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Yes I know, it's all a challenge, I do like challenges!
Now the TV is mine. If you read post #27, you will see I kept if from the owner at a very low price.
So I already ordered a bunch of individual LEDs off ebay. On it's way now.
The method you mention seems good too, but only if you have some half-faulty strips at hand. I wouldn't pay $25 for a bag of 100 units, when I only need 3.
I already have my strips taken off the back panel. Wasn't hard using the blade from a n X-acto knife. I removed the glue from the back of the areas where the faulty leds sit.
I've already tried 2 things
1.-I found a nice heastsink which is flat at one side, and has like wings going alternate directions on the other side, like a claw. These wings fit perfectly onto the soldering iron, so the flat side works as a heating pad. I tried with the strip on it, but the heat wasn't enough
2-Then I put the back of the strip directly onto the iron (the middle section, not the tip), and after a while I was able to remove the LED. I cleaned, added flux, and some fresh solder to the surfaces, and now I have clean and tidy pads.
So for now I'm good until I receive my new LEDs. I guess I will try from the front side, using lots of flux and applying the iron at a low angle trying to touch the pads (really buried underneath) and not touch the LED plastic

[yohnsee]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Looks good so far, keep us posted! Maybe a few pics of the progress would also be nice. But only if you have the time for that

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Yes as soon as I get the new leds in the mailbox I will take some snaps of before & after
Thanks

[edugimeno]

Re: Toshiba 32W3433DL. Backlight shuts off in Auto

Ok, final update on this thread.
I managed to find time to finish this TV. I had all the parts scattered around and needed to do this before I forgot how to put it all back together

I grabbed both led strips and the new leds. I found out it's not that hard to hand solder them. I used lots of flux (the paste brownish flush, not the clear one), and maybe the worst part is making sure it is correctly positioned before applying heat.

Once it looks in its right place, after having added flux both on the solder pads of strip and led, I put the iron tip at an angle so it barely touched the side of the led and the flux helped to distribute the heat to the rest of the pad. At the same time I was applying some pressure down onto the led surface. When I felt the led go down, I went to the other pad.

I repeated this 3 times until all 3 failing LEDS were in place, checked the whole strip with a 24VDC PS, and it worked. Put it back in place, took some time to re-find out the order for the plastic difussers, and after a while the whole TV was back in order.

I had it on for 5-6 hours and it worked perfectly. So I can call it good!

Thanks everyone!