Samsung UN32EH4003F

[Mr_Slim]

Hi All,
This TV appears to have a backlight failure. Suggestions where to start are appreciated.

[handsworth]

Re: Samsung UN32EH4003F

Disconnect cable between the main board and power supply. Backlights should come on when power is supplied. If not, backlights are suspect and prolly need replaced. Also check standby voltage on power supply.

[Mr_Slim]

Re: Samsung UN32EH4003F

Thanks, Are you saying that the backlight should come on even though the power switch, (which is controlled by the mainboard) is disconnected?
Also, where do I check the standby voltage on the power supply?

[Mr_Slim]

Re: Samsung UN32EH4003F

Ok, I see 13.8 V on B13 and 5.3V on B5V, so I expect those are the standby voltages.

When I measure the voltages on the CNL802 connector (the backlight power connector I suspect), (to ground) with the backlight disconnected

1 (D+) = 131.5V DC
2 (S-) = ~1.8V (and it seemed like it was discharging)

4 (S+) = (same as S-)
5 (D-) = 2V

with the backlight connected:
1 (D+) = 130V
2 (S-) = 16.25V

4 (S+) = 16.25V
5 (D-) = 2.2V

[nomoresonys]

Re: Samsung UN32EH4003F

One thing at a time, what is the result of test from post #2?

[Mr_Slim]

Re: Samsung UN32EH4003F

Ok, The backlight does not come on with the mainboard disconnected and power is applied. I see 13V on B13 and 5.3 on B5 as per the board test points. Not sure where else to test for the standby voltages.

[nomoresonys]

Re: Samsung UN32EH4003F

Ok, the problem, I should say a problem, there could be more, but you need to fix this problem first. Since the test failed, there's a problem in backlights/backlight circuit or powerboard.

[nomoresonys]

Re: Samsung UN32EH4003F

Look at this thread, I linked a few backlight testing videos, plenty more on youtube: https://www.badcaps.net/forum/showthread.php?t=122728

[EazyBone]

Re: Samsung UN32EH4003F

Ok, The backlight does not come on with the mainboard disconnected and power is applied. I see 13V on B13 and 5.3 on B5 as per the board test points. Not sure where else to test for the standby voltages.

No need to check MB voltages as it's disconnected and no lights. It's either power board, check voltages coming out to lights, or it's the lights. Sony won't steer ya wrong