Toshiba Regza 42XV635D sometimes doesn't turn on

[JackHack96]

Hi everyone! I'm having a strange problem with my Toshiba TV, which sometimes doesn't turn on, especially after a short time after I shut down it.

If I shut down the TV with the power button on the left while the TV is on and then I try to switch it on again, the green led appears but without any image or sound.
If I try to turn off the TV with the remote controller (or with TV's right panel), then I unplug the wall socket (or I press the power button on the left), when I try to switch it on again, the red led appears but I can't turn it on in any way (even if I try to keep the power button on the TV's panel pressed until the red led blinks).

If I turn off the TV with the power button on the remote controller or the control board on the right panel and then I try to switch it on again (with the remote controller) it usually works.

I assumes the problem is on the PSU, but I'm still a newbie and I'm not sure about that. I disassembled the TV for visual checking the PSU, but the capacitors don't seem to be broken. I also checked the rectifier, and it appears to be good.
Is there anyone who might have an idea about this problem?

Thanks in advance

[CapLeaker]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

I am not convinced at this point that this is a PSU problem. Could you upload high resolution, straight shot pictures of your PSU and the main board?

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

I am not convinced at this point that this is a PSU problem. Could you upload high resolution, straight shot pictures of your PSU and the main board?

Here they are:
https://drive.google.com/open?id=0B-...XhzamtfcmVYVFU
https://drive.google.com/open?id=0B-...lZ6OUp5Yjc0cWc

[CapLeaker]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

They are too dark and not high res enough to zoom in and read things off the boards. We need to be able to identify things written on the boards.

[dick_barton]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

Here they are:
https://drive.google.com/open?id=0B-...XhzamtfcmVYVFU
https://drive.google.com/open?id=0B-...lZ6OUp5Yjc0cWc

Can you also attach them to your post as attachments so that the images are on this site not elsewhere. This is more useful to anyone helping you and anyone looking at a similar fault at a later date.

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

They are too dark and not high res enough to zoom in and read things off the boards. We need to be able to identify things written on the boards.

Ok, I'll try to make them brighter, as for the resolution, my smartphone has a 13MP camera, it's difficult for me to achieve a higher resolution (I do not have other cameras)

Can you also attach them to your post as attachments so that the images are on this site not elsewhere. This is more useful to anyone helping you and anyone looking at a similar fault at a later date.

I tried to attach them, but the image size is too big, that's why I had to upload it on Google Drive, but I can shrink them (but I'll loose quality)

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

I scanned the boards at 300dpi

https://drive.google.com/open?id=0B-...EVmcTJxeDMwWms

https://drive.google.com/open?id=0B-...FlvQnBycm8zWFk

https://drive.google.com/open?id=0B-...XFFa0NjR0VaaFE

https://drive.google.com/open?id=0B-...GhxWkFGblF4M00

[dick_barton]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

Check C889 for any signs of damage and that it hasn't changed its value.

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

Check C889 for any signs of damage and that it hasn't changed its value.

I visual-checked the capacitor, but there are no evident sign of damage (nor bulges, the surface is super flat). My multimeter doesn't have the capacitance measurement option, but I can try to use the resistance method for checking the health of it.

[CapLeaker]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

There aren't any pin outs printed anywhere, so that makes it much harder. Basically there is STBY voltage always generated on the PSU. That goes to the main board, powering it partially. Once you hit that On button on the panel or remote, the main board will send a few signals back to the PSU. So I would be checking for the PSon, the BLon signals to be present at the PSU. That will determent what board we have to look.

When you turn on the TV and it will get the green LED no pic no sound, look and see if the backlights are on?

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

There aren't any pin outs printed anywhere, so that makes it much harder. Basically there is STBY voltage always generated on the PSU. That goes to the main board, powering it partially. Once you hit that On button on the panel or remote, the main board will send a few signals back to the PSU. So I would be checking for the PSon, the BLon signals to be present at the PSU. That will determent what board we have to look.

When you turn on the TV and it will get the green LED no pic no sound, look and see if the backlights are on?

Yeah I read various tutorials even on these forums, but many of them assumes you know the pin outs... Unlucky as always

When I'm in the green led situation, the backlights do not turn on, as the PSU doesn't output the 40V to the inverter (I checked with the multimeter)

[dick_barton]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

Manual available from:-



Page 22 gives the connector voltages.

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

I tried to measure the voltage of POW_SIG pin in P810A when I press the power button, but nothing change. I tried to use an external 3.3v source and I poked the pin with it for a few second, and I can hear the "click" sound of the TV when it turns on (don't know it it's a relay or something similar), but the TV remains off.
I then tried to poke the BL On/Off pin on CN653 with the same external source, hoping it would have switched on the backlight, but it didn't work.

I'm puzzled, I don't know what to do next

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

Hey, now the TV has turned on by itself (it's one of its lucky moments) and I've just measured the voltages of the following pins:

On the P810A connector (PSU)
POW_SIG: 2.80V
POW_LCD: 3.30V

On the CN653 connector (Main)
BL On/Off: 3.30V
PWM: 3.30V

Normally these voltages are 0 when the TV is off.

(sorry for the double post, it seems there's no clear way to edit previous posts)

[CapLeaker]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

Sounds like a main board issue to me. Maybe a bad eeprom. Find the eeprom on the main board, freeze it with a can of air upside down and see if the TV will come on.

[attainteddragon]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

also check any ldo regulators on the main. might get lucky.

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

Sounds like a main board issue to me. Maybe a bad eeprom. Find the eeprom on the main board, freeze it with a can of air upside down and see if the TV will come on.

I never did like that xD
Anyway I shorted the pins of the variuos eeprom, but no luck

also check any ldo regulators on the main. might get lucky.

I'll doubt it, but now I'll check them

[CapLeaker]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

freezing didn't help?

[JackHack96]

Re: Toshiba Regza 42XV635D sometimes doesn't turn on

freezing didn't help?

I tried to freeze it but it didn't helped.
I searched on the web for a replacement of the mainboard, and it's not that cheap (also there is no one who's selling that part in Italy, so I've also have to pay import taxes).
Well, I guess I'll stay with this annoying problem, I was planning to buy a new 4K TV anyway.