Samsung 305T Plus black screen

[andrew1]

Re: Samsung 305T Plus black screen

Yesterday I took with me only the inverter. But after I saw the same problem I went back with the other two boards (SMPS and MAIN). They can't do a full test...I called an hour ago and they have no clue about the problem. BTW is not a certified service or anything. Maybe you still can help me find the problem. I'm thinking if both fuses are blown...the problem should be with the inverter or maybe CCFL lamp? Thanks.

UPDATE: Seams that SMPS and MAIN are good. The inverter has good MOSFETS. Might be something else we didn't think about.

[selldoor]

Re: Samsung 305T Plus black screen

What about those yellow caps on the inverter have they been changed yet

[andrew1]

Re: Samsung 305T Plus black screen

What about those yellow caps on the inverter have they been changed yet

Nothing is changed and I can't do anything about it . I have to belive that we have good caps. From what I read there are alot of posible problems. A transformer or bad CCFL lamp can activate the protection on the inverter board and the backlight will stay off untill you remove them from circuit. I will let him try to fix the problem a few more days. If I have a bad CCFL lamp he can't do anything .

[andrew1]

Re: Samsung 305T Plus black screen

Nothing is changed and I can't do anything about it . I have to belive that we have good caps. From what I read there are alot of posible problems. A transformer or bad CCFL lamp can activate the protection on the inverter board and the backlight will stay off untill you remove them from circuit. I will let him try to fix the problem a few more days. If I have a bad CCFL lamp he can't do anything .

Can somebody tell me from where is sent the "on command" to inverter. He thinks that this could be the problem.

Reminder: backlit is missing, two blown fuses, at least one mosfet...and now a possible "on command" problem. Need advice fast...make sense what he said? Should I find another service before is to late?

[andrew1]

Re: Samsung 305T Plus black screen

Back to the drawing board. After two weeks I managed to take all the components back . The short is gone, the fuses are good...but we have no backlit. Waiting for the next step

[andrew1]

Re: Samsung 305T Plus black screen

Back to the drawing board. After two weeks I managed to take all the components back . The short is gone, the fuses are good...but we have no backlit. Waiting for the next step

OK. You can close this thread. Seams that people are not as friendly as I thought. I find it hard to believe that nobody has a clue about step-by-step troubleshooting.

[andrew1]

Re: Samsung 305T Plus black screen

I'm back with another question if somebody want to help me. I did everything that was told and seams that i'm moving in the right direction.

From mainboard:
BL_EN = 2.7V
Status = 3.3V
all 24V lines are ok.

Problem I found: The inverter IC (BD9886FV) has no input voltage (pin 28).
Look at this pictures for an obvious bad capacitor or maybe you have a clue from where should I start tracking the problem. Thank you.

[robo4130]

Re: Samsung 305T Plus black screen

I have a black screen with backlight on was kines befotr 375 @7 min in oven but put back together and backlight and power button only

[robo4130]

Re: Samsung 305T Plus black screen

With lines but selftest worked flashing colors