SAMSUNG LE40C530F1W no picture with sound

[takisp]

Hello there i am having a problem with my samsung tv

The problem is the same with this one
https://www.badcaps.net/forum/showth...ht=bn44-00340b

I think i found the problem but i dont know how to fix it

The inverter circuits of this board does not run off the 24V power supply, it runs off the PFC Voltage booster which is >360VDC, the main inverter is on the power supply board, the board connected to the lamp is the balancer board.
You need to find out if you do have >360VDC on the fuse (tested good per your post) in the middle of the board, use the negative leg of the main filter cap as the ground ref. point.

I did the test budm said i am counting only 305v at the middle fuse


AC line voltage at greece is 230V

How can i fix this ?
Thank you

[budm]

Re: SAMSUNG LE40C530F1W no picture with sound

If your line AC Voltage is 230 VDC, then the DCV between the two legs of the main filter cap should be around 330VDC when TV is in stand by mode, and when the TV is turned on then the DCV should jump up to be > 360 VDC (usually will be closed to 400 VDC).
305 VDC does not look right at all. You should verify that your meter is OK.

[takisp]

Re: SAMSUNG LE40C530F1W no picture with sound

thank you for your reply i will try to find a new meter and try again !

[takisp]

Re: SAMSUNG LE40C530F1W no picture with sound

i tried again with a new meter and it looks wierd again!

standby i have 322v and when i turn on the tv it goes a little bit down to 317v

[takisp]

Re: SAMSUNG LE40C530F1W no picture with sound

any ideas ?

[budm]

Re: SAMSUNG LE40C530F1W no picture with sound

322V is pretty close to 325vdc (AC @230vac) What is the measured AC feeding the TV? Multiply that by 1.414 to get what you should have between the two legs of the main filter caps.
'Samsung LE40C530; turned on, flickered, now no backlight (but picture/sound work).' You are saying that you have the problem as OP? You have no backlights but you do have sound just like OP then?
Check Diodes DP801, 805.
We need to get that boosted Voltage first, you do have have standby Voltage and all the commands signals from the main board, right?

[takisp]

Re: SAMSUNG LE40C530F1W no picture with sound

with everything connected to the psu and the tv turn on i am having these measurments

pin1-3-5-15-17=12,7v
pin7-9=0v
pin11-13=5,2v
pin2=0v
pin4=4,4v
pin6=2,06v
pin8=1,70v
pin10=0v
pin12=0v
pin14=5,2v
pin16=5,2v
pin18=1,5v

Yes problem is the same i have sound and the backlights does not open but i can see the picture moving with a flushlight.

both diodes was ok

[takisp]

Re: SAMSUNG LE40C530F1W no picture with sound

should i order a new psu or could be something else ?

[budm]

Re: SAMSUNG LE40C530F1W no picture with sound

At this point you do need new power supply/inverter combo board since the PFC Voltage booster is not working right now.

[takisp]

Re: SAMSUNG LE40C530F1W no picture with sound

At this point you do need new power supply/inverter combo board since the PFC Voltage booster is not working right now.

Thank you dudm!
One last question plz my psu is the BN44-00340B REV 1.4 i have found the same board but REV 1.2 is this ok or i sould find exactly the same?

[budm]

Re: SAMSUNG LE40C530F1W no picture with sound

1.2 is an older revision, I would get the same revision or newer revision. They may have released new revision to fix what they found on the old revision.

[HellasTechn1]

Re: SAMSUNG LE40C530F1W no picture with sound

I have a very similar problem with the same model. In my case it would power on but backlight does not come on at all. I measure the voltage on the main filter caps with the TV powered on and logic bord connected and i get like 305 Volts like takisp.

I also found a bad zener. The ZDP804

[HellasTechn1]

Re: SAMSUNG LE40C530F1W no picture with sound

After removing and checking the ZDP804 it appears to be ok. Also i replaced the PFC chip and nothing changed.

[budm]

Re: SAMSUNG LE40C530F1W no picture with sound

We need to verify if you do have the VCC to run the PFC IC or not first.
BTW: your power supply board is BN44-00340B?

[HellasTechn1]

Re: SAMSUNG LE40C530F1W no picture with sound

I think that is the psu. I will confirm it and get back here.

The vcc i measure between the resistor pr823 and GND or chasis ?

What voltage should i expect ?

[budm]

Re: SAMSUNG LE40C530F1W no picture with sound

You are working in the primary side of the circuit so the Ground reference for the primary side of the circuit will be the negative leg of the main filter cap (the big electrolytics cap with 450VDC rating.

[HellasTechn1]

Re: SAMSUNG LE40C530F1W no picture with sound

You are working in the primary side of the circuit so the Ground reference for the primary side of the circuit will be the negative leg of the main filter cap (the big electrolytics cap with 450VDC rating.

Got it... Any idea what voltage should i be expecting ?

[budm]

Re: SAMSUNG LE40C530F1W no picture with sound

15~18VDC range is typical, best to get the P/N of the PFC IC to look up the spec. sheet.