Samsung ue324h5000w no backlight

[LE GRAND]

Re: Samsung ue324h5000w no backlight

after changing 2S110 now 318v in main cap

[dick_barton]

Re: Samsung ue324h5000w no backlight

How did you verify the 4 led strips?

[LE GRAND]

Re: Samsung ue324h5000w no backlight

OK WITH Lab Mains Adapter BT305
IN EACH STRIP I give 30v 0.30 amp

[LE GRAND]

Re: Samsung ue324h5000w no backlight

Any idea ,???????????????????

[dick_barton]

Re: Samsung ue324h5000w no backlight

So the 4 strips tested at 30V, 300mA per strip would appear to show the leds are fine. The board says 140V @ 260mA. With 4 strips in series would be about right.

without the schematic for the power supply it is difficult know what else to check.

However the Backlight On and P_Dim should not be 0V and you already said that with the main board disconnected and connecting A5 to BL_ON using a 1K resistor and A5 to P_Dim again using a second 1K resistor did not bring the leds on.

What voltage do you have on each side of D9101

[budm]

Re: Samsung ue324h5000w no backlight

What DCV do you have between GND and the Cathode (band) of DM852? That Voltage (low Voltage) is the feeding Voltage that feed the Boost converter circuit to produce the 140VDC for the LED.
I expect to see that feeding Voltage (low Voltage) to be present at all time.

[LE GRAND]

Re: Samsung ue324h5000w no backlight

voltage on each side of D9101 -----------0.00V
voltage oN DM852------------60V

[dick_barton]

Re: Samsung ue324h5000w no backlight

What's the IC part number as printed on it.

[LE GRAND]

Re: Samsung ue324h5000w no backlight

may be SLK2012M IM NOT SURE I CANT READ

[dick_barton]

Re: Samsung ue324h5000w no backlight

Cannot find anything on that number but could find SLC2012M listed as a power supply drive control IC

[dick_barton]

Re: Samsung ue324h5000w no backlight

The IC looks very much like a FAN7340 in layout. Can you measure very carefully what DC voltages you have on the pins 1 - 16 with the black meter lead connected to pin 3.

http://pdf1.alldatasheet.com/datashe...D/FAN7340.html

[dick_barton]

Re: Samsung ue324h5000w no backlight

What's the part number and what voltages do you have on the 3 pins?

[LE GRAND]

Re: Samsung ue324h5000w no backlight

Gnd is 4 leg

1. 12 .8 v
2. 105 mv
3. 105 mv
4. Gnd
5. 4 .8 v
6. 120 mv
7. 86 mv
8. 105 mv
9. ~4 v
10. 3.5 v
11. Nc
12. 100 mv
13. 105 mv
14. 93 mv
15. 0.77 v
16. 87 mv

[dick_barton]

Re: Samsung ue324h5000w no backlight

Good find.

[LE GRAND]

Re: Samsung ue324h5000w no backlight

MDD5N40 N-Channel MOSFET

D 124V
G 0V
S 0V

[dick_barton]

Re: Samsung ue324h5000w no backlight

Here's a Samsung model using the same LED driver giving voltages.

So you have your 120V for driving the leds. What voltage on pin 11? It's pin 10 that's NC.

Looking like the led driver is faulty since there does not appear to be any drive voltage to the mosfet.

[dick_barton]

Re: Samsung ue324h5000w no backlight

Just taken another look at the information you provided.
If the drain of the mosfet is at 124V then that should pass through a diode and arrive at CNL802.
Can you confirm the 124V is on pins "Top1-"

[LE GRAND]

Re: Samsung ue324h5000w no backlight

BIG THANKS TO dick_barton
After changing SLC2012M the backlight is coming

[dick_barton]

Re: Samsung ue324h5000w no backlight

Thank God. I though we would never get there.

[LE GRAND]

Re: Samsung ue324h5000w no backlight

hhh me too