Toshiba 37RV555D - black screen, green led goes off after few secs

[h2pc]

Hey,
My father told me to trash his broken TV, so I decided to look inside it and maybe learn something

Here is the thing - after I plug in the TV, standby red led is on. I press "power", there's relay click, green led goes on for a few secs, screen is black all the time, green led goes off, relay clicks again.
Standby voltage is 5V, after I press "power" and measure transformers voltage, everything seems right(according to schematics), PFC voltage is 315V. One thing that seems off to me is voltage on IC MPD6S030(page on schematics titled as SW/T-Con Reg) - output voltage should be 12V_LCD. There's 0V on this pin. Pin "on/off" of this IC is supplied by 5V from standby and a signal called POWER_LCD, which is 0V. I looked on the schematics and found that POWER_LCD signal comes from main board from AND gate (IC 7S08FU). It needs 2 signals - POWER_LCD_SW and RS_POWER_LCD. Both come from IC FLi32626H. Standby voltage on those pins is ~0.15V. After I press "power" switch, voltage drops to 0V.

Do I look at the correct spot? I stucked at this place and dunno where else to check. Hope there's someone here who could give me some advice. Thanks in advance.

[budm]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

'PFC voltage is 315V' if the PFC circuit is on it should be close to 400VDC if this TV has PFC.
We need good clear pictures of the boards and close up pictures of the connectors so we can see the labels for the pins of the connectors.
BTW, upload the service manual so we do not have to look for it.

[Diah]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

try to flash firmware again bin format. sorry i dont have for RV, i have for RL

[h2pc]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

I read somewhere that PFC voltage should be 1.4 times main voltage, which at 220VAC should be ~310VDC. I assumed that's correct. If not I'm gonna look after that.
I Uploaded schematics. Page number 75 is the one I think seems odd. It's night in here so I'll post pictures tomorrow morning. But on the schematics page 68 there are connectors with labels. Hope it'll help.

Will try to flash firmware if I find one. That's at least some idea to start with.

[budm]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

When TV is in stand by the Voltage on the cap should be = incoming AC x 1.414, so if your AC is 230V, then the Voltage on the cap will be = 325vdc, when the PFC is turned when the power supply board gets the PS-ON signal from the main board the DCV on the cap will go up to around 400VDC.

[budm]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

BTW, is this your power supply?
Picture provided by shopjimmy.

[h2pc]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

To be clear - by the voltage on the cap you mean voltage on the PFC_OUT pin? Which in fact is voltage on the output of the bridge rectifier? In my case this bridge rectifier is supplied by voltage from relay which short circuit one resistor. So if I assume well, there must be something with my resistor or with relay? I'll check tomorrow morning and post back the results.

EDIT: Yup, it looks like my power supply board

[budm]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

Look at page 4 of the PDF, you'll see ICs, Power Power MOSFETs, PFC inductors, diodes, they are for the PFC Voltage booster circuits.

[h2pc]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

Ok, I checked voltages once again and it seems I was wrong, PFC voltage is 388V while "power" is pressed and 308V on standby...
Seems I gotta look for the firmware and see if it helps.

[R_J]

Re: Toshiba 37RV555D - black screen, green led goes off after few secs

.