Samsung LN46E550 no backlight

[Jtroutt19]

Hey guys got this tv in front of my that has no backlights. I have no voltage at the back connector either. Bought a rebuild kit off eBay. Still no backlights and no voltage at connector. Thoughts.

Replaced all parts in red

[diif]

Re: Samsung LN46E550 no backlight

What testing/measuring did you do before fitting the kit ?
What's the voltage across the main caps ?

[jetadm123]

Re: Samsung LN46E550 no backlight

Check fuse next to the large caps. Also, the main fuse if you get no voltage across main caps.

[Jtroutt19]

Re: Samsung LN46E550 no backlight

Voltage across main caps is 394 volts. Fuse next to main caps is good.


The only testing I did before fitting the kit was checking for voltage at connector for backlights,

[diif]

Re: Samsung LN46E550 no backlight

Did you test at the LED connector correctly as you turned on the TV ?
Voltages at the other connector ?

[jetadm123]

Re: Samsung LN46E550 no backlight

A good focused shot of the other side of the power supply would be good as these power supplies were known to suffer from bad solder joints.

[Jtroutt19]

Re: Samsung LN46E550 no backlight

yes I tested for voltage as unit was powered up. I tested for voltage at the powersupply connector. I have went over this board with low power magnification looking for bad solder joints have not found any. I will look over it againl

[budm]

Re: Samsung LN46E550 no backlight

The output (primary drive for the inverter transformer) CNI801 of the power supply board go the inverter transformer board.
We need to know if you do have BLU_ON at pin 6 of the connector CN802 or not.
It is best to report all the dc Voltage of all the pin of CN802.
Notes: exposed pins on the top side of the boards are the ODD Number pins, the EVEN number pins you have to probe from the back side of the connector.
You must report the pi name and number and follow by the reading when TV is OFF and when the TV is turned ON.
For eaxmple:
TV off TV ON
PIN 1 (B13V) = XX XX
PIN 2 (P_DIM) = XX XX

BTW, if you look at the LCD panel in the dark room, do you see the backlights even flash on for seconds?
I suspect the DC Blocker CI818 (2W 474K, SIC 460S series) to be bad, it is commonly failed cap in the inverter circuit. Look real close to see if it bulging from the side, or remove it and test its capacitance.
Did the repair kit come with that cap? It should.


Samsung BN44-00441A (I46F1_BHS) Power Supply Unit
http://www.shopjimmy.com/samsung-bn4...upply-unit.htm