Toshiba 40TL933

[VHSFI]

Hi Everyone,

So i have this TV that is apparently dead, no standby led and no response to any remote or buttons press.
The only signal i got on the psu side is 5V witch will be converted on the mainboard side to 3.3V_STANDBY witch i was able to track and is present.
I am trying to figure out where the problem lies (mainboard / psu) any tips are welcome.

Thx in advance.

[yokoono]

Re: Toshiba 40TL933

The stb LED is lit by the processor. So it may be defective (processor) motherboard or corrupt software.

[VHSFI]

Re: Toshiba 40TL933

I also forgot to mention that the set started to shutdown by itself after a couple minutes of being on and a few times even turned on by itself.

[nomoresonys]

Re: Toshiba 40TL933

Check your solder joints, might not be the issue but easy enough to check, images of bad joints: https://www.google.com/search?q=bad+...ih=607&dpr=1.5

[nomoresonys]

Re: Toshiba 40TL933

maybe also check all the electrolytic capacitors around the connector on the powerboard and all the diodes.

[VHSFI]

Re: Toshiba 40TL933

Update:
So i can't find anything obviously wrong in either the psu or the main, so i decided to do a test and supply the mainboard with +5 and +12v and the main board works i get the standby light and the board turns on and off with the remote or power button.
Does anyone knows if this psu is also supposed to output +12v while in stanby.

[Diah]

Re: Toshiba 40TL933

Does anyone knows if this psu is also supposed to output +12v while in stanby.

No, its generate only 5V at STB.
actually i have this PCB and i did use it as out source Voltage 12 /24V generator. as its stable and enough current it supply. you can as standalone testing with out MB..

[nomoresonys]

Re: Toshiba 40TL933

No, its generate only 5V at STB.
actually i have this PCB and i did use it as out source Voltage 12 /24V generator. as its stable and enough current it supply. you can as standalone testing with out MB..

+1, stand alone test is the way to go.

[VHSFI]

Re: Toshiba 40TL933

So how do it turn the psu on without the mainboard? Is it that wire i see on the back of the board in the picture you posted? Also are there any other signal present besided the +5V when the psu is in standby (AC_DETECT/ POWER_TV / POWER_SIG....)

[Diah]

Re: Toshiba 40TL933

So how do it turn the psu on without the mainboard? Is it that wire i see on the back of the board in the picture you posted? Also are there any other signal present besided the +5V when the psu is in standby (AC_DETECT/ POWER_TV / POWER_SIG....)

from your questions tell me you are with ZERO TV Technique. so let yours finger out from this work. all will be on yours risk.

i showed you the only jumpers which make the PCB run as standalone and produced 12 & 24 V. and this what the tv need.
the jumper wiring:
pin 9 = 5V ( STB )
pin 11 = Power Tv ( its power on signal which the MB send )

[VHSFI]

Re: Toshiba 40TL933

Appreciate the feedback, and while i am not a professional i am aware of the dangers and where i can not put my fingers the questions i make may a seem a bit newbish but that's just because i just want to be sure i don't mess up.

As for the psu it's dead, it does not power up, gonna check a few components in the area, you think it can be an optocoupler ?

[Diah]

Re: Toshiba 40TL933

Appreciate the feedback, and while i am not a professional i am aware of the dangers and where i can not put my fingers the questions i make may a seem a bit newbish but that's just because i just want to be sure i don't mess up.

As for the psu it's dead, it does not power up, gonna check a few components in the area, you think it can be an optocoupler ?

i don't repair on method buying watermelons . if it come red or white.

put the jumper always between pins 9 -11 and follow the 5V on pin 11 rail from the back side.

[nomoresonys]

Re: Toshiba 40TL933

ok, so 1 2 3, JUMP PINS 9 AND 11, THEN LOOK FOR 12 AND 24 VOLTS, report results, online troubleshooting is not easy, the helper does not have the set in front of them so they need detailed info. from test results, best to do a test get results then go on from those results.

[VHSFI]

Re: Toshiba 40TL933

Sorry if i give a poor response, i will try to be more on the point.

So pins 9-11 jumped, no 12v or 24v present
Attached picture shows the measurements at several points following pin 11 path.

[Diah]

Re: Toshiba 40TL933

yours pin 11 Path healthy.. you have in primary PFC didn't turn on high.
measure the main caps currents at primary with and with out the jumper

[nomoresonys]

Re: Toshiba 40TL933

.

[nomoresonys]

Re: Toshiba 40TL933

did you measure those main caps? they are the big ones, put a probe on each leg of the caps + and -, as always for those looking on be very careful HIGH VOLTAGE.

[VHSFI]

Re: Toshiba 40TL933

Main filter caps are at 327v with and without jumper.
Also don't know if this helps but there is no voltage present on U1 (L6571B) pins 1&4.

[Diah]

Re: Toshiba 40TL933

you have open circuit at primary. check the circuit near the coil filter B1 and all component close to it as well check if you have broken at the print lines layout on PCB hope R-J assets you he is .good at PCB primary troubleshooting

[VHSFI]

Re: Toshiba 40TL933

Thx for the help, i will give a check in the primary section, will report my findings.