Toshiba 37CV500P - Brak podświetlenia, wymienione elementy, LED miga 2 razy

Question

hello i have a problem with my toshiba 37cv500p, it has sound but no image.

the invertor modell is 6632L-0506A, i already replaced:
2x C 680uf/35v
BD9897Fs
4x FDD 8447L

But still no image.

when i press the power button, there is a led on the invertor board that flashes 2 times but still no backlight. when the led flashed i get 1.8v on the STATUS pin. than it goes to 0v
i have 5v on the ON/OFF pin
and at the output of the mosfets i have 5.5v

any ideeas?

thank you

guard10 · Answer

Hey, If you can you first of all can check the CCFL bulbs if they are ok you will have to replace BD9897* because most likely that what is causing the problem. Below link attached:

brogdan · Answer

i already replaced all of the parts in the link.

guard10 · Answer

Hey check the CCFL bulbs.

brogdan · Answer

CCFL bulbs tested OK!

guard10 · Answer

Hey Take a photo of the inverter oki?

brogdan · Answer

here is a photo the parts marked with red ARE REPLACED and the 2 white lines indicate the values i have measured

guard10 · Answer

Hey check ZD1,how is ok connect the capacitors to the CN3 and CN4 2.7nF-3.9nF 3000v.Check as flashing LED

brogdan · Answer

i have checked ZD1 with multimeter and is OK

i don't exactly understand what you tell me to do...
you want me to connect 2 extra capacitors to CN3 and CN4 and check if the LED is still flashing? with CCFL connected?

guard10 · Answer

Hey ccfl not connected.

brogdan · Answer

ok i will try that first thing in the morning andi will let you know

Dodano po 11 [minuty]:

this test is for checking that the invertor is ok, to see if ccfl bulbs are ok? or what?
because i tested the CCLF bulbs, i powered them on with a laptop inverter and the screen got light.

brogdan · Answer

hello
i did the test and the same. the LED on the invertor board flashes 2 times
but i think it goes in some error or protection because the STATUS PIN should read 1.8V all the time (this is what i read in other forums) and mine goes 1.8V for 1 second then 0v, then again 1.8V for 1 second and after remains 0V

zbyszekskibinski · Answer

Hi Brogdan

If you assume that status pin should stay at 1.8V at all times, why not disconnect that inverter from main board first and see what happens? Just pull out all dimming pins and the status pin from signal board and leave supply pins and ON/OFF pin connected. Check status pin now and if necessary, jump 1,8V in there by drop-down resistor from 24V rail.
Good luck!

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brogdan · Answer

I did that, and from the signal board comes a 3,3v on the status pin, and the invertor board should take it down to 1.8v. it makes it 1.8 v for 1 second and then it grounds the status pin to 0V

zbyszekskibinski · Answer

And if this is happening theres no flash on display even for a sec.?Can you hook up your scope on drains of SMD mosfets you outlined red in the picture/the bottom ones/ to see if sqare waveform comes up after inverter start-up? Sometimes CCFLs can light up ok when connected to lamp testers or when ignited individually however they still wont work with the tv they have been fitted in.

Promuję tematy:
27.09.2022 LG 42PJ350-ZA - działa wyrywkowo, klikanie przekaznika
28.12.2017 Blaup. 32/141I-GB-5b-HBKUP-EU - Poszukuję wsadu 25Q32 TP.MSD309.BP85

brogdan · Answer

nope, no flash on the display. unfortunately i don't have a scope here to test the waveform..

zbyszekskibinski · Answer

You will need to 'fool' BD inverter controller IC, to bypass CCFL time-out pin first to rule out, CCFLs then, as the inverter might be too sensitive to old and slow-start tubes, however if that was the case, you should be able to see the flash for the second, looks like inverter is defective, test voltages on BD chip, make sure it gets Vcc supply and other voltages according to its PDF file

Promuję tematy:
27.09.2022 LG 42PJ350-ZA - działa wyrywkowo, klikanie przekaznika
28.12.2017 Blaup. 32/141I-GB-5b-HBKUP-EU - Poszukuję wsadu 25Q32 TP.MSD309.BP85

brogdan · Answer

i checked VCC=24V , standby pin is 5v(ok)
what elese to check? SS Pin? this is the slow start control. but i don't understand exactly from the pdf... do i need to have a lower voltage than 2.2v on this pin to activate slow start?

zbyszekskibinski · Answer

Check pin 17 (CP) and ground it to override CCFL time-out, all in all, I think the problem is still in inverter board, something else has failed on that board, sometimes replacing a full kit won't solve the problem as more components have faulted on the board, sorry can't be of more help...

Promuję tematy:
27.09.2022 LG 42PJ350-ZA - działa wyrywkowo, klikanie przekaznika
28.12.2017 Blaup. 32/141I-GB-5b-HBKUP-EU - Poszukuję wsadu 25Q32 TP.MSD309.BP85

brogdan · Answer

thank you for your time, i grounded pin 17 but still no backlight..
i also measured all the other tansistors and diodes on the invertor board, and can't find anything wrong

just don't know what to do more

Toshiba 37CV500P - Brak podświetlenia, wymienione elementy, LED miga 2 razy

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