Samsung LN32B350F1 no video

[brianr20v]

Re: Samsung LN32B350F1 no video

Will do I will let u know.

[brianr20v]

Re: Samsung LN32B350F1 no video

ok so I just heated the board with the blow drier and didn't get no change it didn't turn on.

[tom66]

Re: Samsung LN32B350F1 no video

No change in voltage across those capacitors?

[brianr20v]

Re: Samsung LN32B350F1 no video

no change in voltage across the caps .

[tom66]

Re: Samsung LN32B350F1 no video

I would suggest changing them anyway, to get us a baseline. There is no worry about using non low-esr capacitors there, just match the capacitance and ensure voltage is more than or equal to the original rating.

[brianr20v]

Re: Samsung LN32B350F1 no video

ok change the caps CM808-13.1v,CM804-13.1v and CP809-11.12V now don't want to sound stupid but am I suppose to get shock when I touch on top of those small caps ?
CP809

[budm]

Re: Samsung LN32B350F1 no video

The section you are working on is the HOT side, so do not touch anything with your hands, deadly section.
To be safe, you should plug the TV into GFCI outlet or use isolation transformer.
if I remember correctly, the voltage on CM804 was 20v or more.
QB801, Zener diode (15v) ZB801 tested OK?

[brianr20v]

Re: Samsung LN32B350F1 no video

yes ZB801 tested good.

[budm]

Re: Samsung LN32B350F1 no video

OK, take the reistance reading of the PFC controller IC UP801S between pin 8 (VCC) and the Ground pin 6, take the reading both ways (reverse the meter's leads after taking the first reading), report the reading, make sure to tell us if the meter is showing Ohm, K OHM, or M OHM.

[brianr20v]

Re: Samsung LN32B350F1 no video

U mean UM801s? did it open circuit both ways.

[brianr20v]

Re: Samsung LN32B350F1 no video

sorry my mistake found the IC. 10.90Kohms black lead to pin8 and red lead to pin6 and reverse 10.98kohms

[budm]

Re: Samsung LN32B350F1 no video

Ok, that is not the cause of low voltage then. Something is loading down the power supply, the voltage at the Emitter of QB801 which feeds the VCC of the PFC IC should be about 15V, QB801 is setup as a 15V linear regulator. I have look at the diagram more to see what else you will have to test.

[brianr20v]

Re: Samsung LN32B350F1 no video

ok no problem thanks

[brianr20v]

Re: Samsung LN32B350F1 no video

ok so I did some soldering on the power board and what u know the backlights are coming on now when I pull out the white connector but the TV still not powering up?

[budm]

Re: Samsung LN32B350F1 no video

Hey, that is great! Which section that you re-solder? Also what DC voltage do you get at the big cap and at those test points so I can put the notes of the voltage readings in the diagram.
So do you get ps_on on the pin when all the connections are put back together?

[brianr20v]

Re: Samsung LN32B350F1 no video

ok well the backlights comes on some times now the TV actually turned on around twice when I put the connector back in after a while it switched on tried switching it of and on with the remote didn't come back on?

[budm]

Re: Samsung LN32B350F1 no video

I think the main key is the voltage on that large cap has to be around 380V for the backlights to work properly.

[brianr20v]

Re: Samsung LN32B350F1 no video

when the backlight is on the voltage at CP815 is 312v,did some soldering at CM852 and CM876 was checking the caps.

[brianr20v]

Re: Samsung LN32B350F1 no video

when the backlight is on the voltage at CP815 is 312v,did some soldering at CM852 and CM876 was checking the caps.

look at the pics with the backlight on.

[budm]

Re: Samsung LN32B350F1 no video

The 312V is very marginal for the inverter circuit to work properly. Do you have capacitor meter to check the capacitance of that large cap since if the PFC not working, I expect the voltage on the cap to be at 230V (your country line voltage) x 1.414 = 325V but with very poor regulation due to failed PFC.