TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

[Sraros]

Hello guys,
I have a.m. TV trying to find out what is wrong. I am pretty amateur in electronics so I appreciate any help.

When connected to the AC, powers up straight away instead of going into standby (light on TV goes green straight away), displays the TOSHIBA logo then goes off, then backlight turns off for a sec and then stays on forever showing nothing and TV won't obey neither remote control nor buttons at the sides. So only way to shut it off is pull the plug.

Now, since I couldn't take the whole TV with me, I pulled out the power supply board. When plugged in power, I measured the outputs that go to the main board and saw only on the 10th pin voltage, jumping from 5.01 to 5.02
I don't know if the readings are false because the main board is disconnected.
All caps show in good physical condition. CEM3 to CEM8 show no voltage at the multimeter same as upper right CEM7 and CEL2.

Any advice where to go next?

[dick_barton]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

With the power supply isolated from the main board connect CN2 pin 13 (PWR_ON) to pin 10 (5VS) using a 1K resistor and see if the other voltages come up. They should according to what you have said in post #1

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Hello again. Dick_barton thx for your advise, I just preferred to take the whole TV...finally to get things going. So at last hooked TV altogether again and I have these suspicious readings on the multimeter.

PWM1= 0,47V
PWM2= 3,28V
BL_ON= 3,33V
POWER_TV= 3,25V

The rest voltages are pins 1,2,3,6= 12,17V
pin 10= 5,02V

[zomi]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Download firmware and update from toshiba site

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

So, trying a firmware update didn't really do sth. I have the same things going on, only that now the toshiba logo doesn't flash.

Trying to get a little deeper, I figured out the PSU is actually fine. The voltages are correct just before some little diodes, so it must be sth wrong with the mainboard.
Trying to physically inspect, I see this component IC122, Winbond 25Q16 (EEPROM?) maybe is broken and leaked?

In the last picture I scratched a bit the white stuff on it and seems like a hole.

[vinceroger69]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

That indent on the ic is too just identify pin one so the ic is probably fine but it does sound like a firmware issue still

[dick_barton]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

As vinceroger69 says that's just the EEPROM identification of pin 1.

Power_On, CN2 pin 13 should go to 0V when in standby and also BL_ON_OFF CN2 pin 14 should also go to 0V when in standby.
If they don't then it would appear to be a mainboard fault or an EEPROM problem.


Edit
You can try a firmware update.
http://www.dl.toshiba.com/tsb-dtv/NA...39L4333DF.html

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Yes, I understand it's for identification but the white stuff around it got me thinking. Anyway checked it with the multimeter and all fine there.

Dick you are right. I went through the whole motherboard again with the M/M, and afterall that IC was fine. Where I found a short was in the EEPROM 24C256BN, (IC610). I was like "here you are" but removing and checking it, it was actually fine. What was shorting was a small capacitor near it, like a bad soldering or sth. I don't know if some technician looked through it before I got the TV.

So... after soldering the IC back and cleaning the short to the little cap, I gave some more tries... but still same things. LED light goes immediately green, and only backlights flash. No buttons, no remote. Tried updating (which I find hard to apply when buttons don't work) nothing. And the voltages are still the same.. Gave it a few cycles of power on/off, nothing. Can it be that this EEPROM needs replacement?

[dick_barton]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Have you tried updating the firmware as post#7
I see you say you tried so did you download it to memory stick and follow the instructions.

[vinceroger69]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

The only other option i guess is find a eeprom dump remove and re programme the ic and replace it or try to purchase a pre programmed ic but its a risk as we dont know if this is the issue.

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Have you tried updating the firmware as post#7
I see you say you tried so did you download it to memory stick and follow the instructions.

Well I did the procedure as the instructions in TOSHIBA website but the screen stays blank. Like nothing really happens even though I waited about 5'.
I think I will order one of these 24C256BN ICs and replace it just to see where this goes.

The guy in this tutorial seems he replaced it with a blank and the TV rewrites.
https://www.ifixit.com/Guide/Samsung...lacement/14574

[vinceroger69]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

some samsungs do but not sure about toshiba sets

[vinceroger69]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Well I did the procedure as the instructions in TOSHIBA website but the screen stays blank. Like nothing really happens even though I waited about 5'.
I think I will order one of these 24C256BN ICs and replace it just to see where this goes.

The guy in this tutorial seems he replaced it with a blank and the TV rewrites.
https://www.ifixit.com/Guide/Samsung...lacement/14574

does the led flash on the front of the set or usb stick while you are trying to update? how long did you leave the usb in as some sets can take a long time to update

[dick_barton]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

So you formatted the USB stick as suggested. I think it's FAT32. And also ensured the file had the right name and was in the correctly named directory, if stated in the procedure. Also if there are more than 2 USB ports you have to insert the stick into the one as shown in the procedure pdf.

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

I quote from the instructions:
"The USB Thumb Drive should be formatted as a “FAT” or “FAT16” file system and NOT “FAT32”."
I don't think it makes a difference at which port you put it. This would be insane :P
In any case though the image shows a TV with one USB and one HDMI, so it's more like "put it like this at your TV"

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Hi guys, coming back after quite a long time...
You can all say I told you so! :P It was afterall a firmware issue, at least to a point. Pretty unbelievable but with a different USB drive it worked! It was listed in the download instructions but I didn't give much notice. So, the TV LED flashed for 3-4 minutes and then stopped so I guess it was done and now at least the power button on the side works.
However in the whole procedure of the firmware update I didn't have and still don't have a picture. Neither the TOSHIBA logo flashes at start

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

I just connected over HDMI my laptop playing some music. I see it recognizes it since music stops but it's not heard over the TV, even though I press the source and volume button multiple times

[dskall]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Are you still getting your bl_on voltage?

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Yes 3.33V
I went a quick MM test on the BL board and found these shorted as shown in the photos. I don't know if the ones except the little caps should be or not.
I am trying to find a schematic but no luck

[Sraros]

Re: TOSHIBA 39L4333D, powers on, no standby, backlight on, won't shut down

Update: connecting with a SCART cable, I get sound and the Backlights go brighter. When I press the settings button I see the screen goes even brighter so I guess by now the main board is fine, only the BL board is messed.

I recalled when the TOSHIBA logo stopped flashing on start and maybe connected to this. While the TV was on, I was testing with the MM set to voltage the cable that goes from power board to main board. I put by mistake the red probe to ground and black probe to BL_ON turning the lights for half a second off and then back on. Could it be that such a thing could damage the BL board?