SAMSUNG LE32D400E1W - No Power to Backlight

[leo-saphira]

Hi Folks

A new one for you all

I have a SAMSUNG LE32D400E1W here with a fault on the PSU - I am not getting no power to the Backlight circuit from the PSU board (checked voltages and showing as nothing/fuses are ok

With the TV on and a torch the TV boots and shows the image with no back light

Board is BN44-00438A I2632F1_BSM

Any pointers please.

[newtothis]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

Ohms... Black to screw and red to each fuse... Results?

[leo-saphira]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

F1 110V (should be 240v?) - no reading
F2 5.9v -224k

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

OK, those two fuses are in the PRIMARY HOT DEADLY SIDE of the circuit, you will not use the screw or the chassis as the ref point for testing the Voltages.
Also DO NOT test the resistance if the TV has power.
Check the resistance between he two ends of the fuse, it should be <1 Ohm.
The main fuse is OK other wise you will not have the power supply working to produce pictures on the screen, you do not have backlights so you need to find out if the inverter circuit is getting b+ and correct B+ to run, if it is getting BL-ON to turn on the backlights.
Check the DCV between the two legs of the main filter cap when the TV is turned off and when the TV is turned on also.

[newtothis]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

Was checking for a short on primary to ground, I had one that had a short to ground hence to resistance check

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

OK, but he was checking the AC voltage instead and that is why the Voltage reading (110V) is wrong.
I also do not understand as to no reading for the main AC fuse F1 means, he can see image on the screen using flash lights so the main board and the power supply is functioning. I do not believe he is doing the measurement correctly. It looks to me he is measuring the resistance with the power applied to the TV.

F1 110V (should be 240v?) - no reading
F2 5.9v -224k

[newtothis]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

I read wrong and didn't read "fuses are OK" Obv no shorts if they are fine.....

OP are you suing Ohms setting while TV is powered on?

[YiannisQ]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

I have the same issue with this model.
I have check the fuse it's ok and i have the 12volts in the inverter pin 11
SMPS board : BN44-00438A
Inverter : sst320-4ua01

[YiannisQ]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

some more measurements that i take
first the name of pin then the voltage in standby and on power

B13V---> 0.0V------- 12.86
B5V----> 0.0 ---------5.27
P_DIM--->0.0 ----------0.8--------------CN802
BLU------>0.0----------5.14
A5V----->5.26 ----------5.26
PS_ON-->0.0 -----------3.53



LD---->0.0----------11.50
VCC-->0.0-----------12.80--------------CNI801
CNT_PRT-->0.0--------12.2
OVP--->0.0-----------0.0

[YiannisQ]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

another manual for BN44-00438A

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

Are you getting about 400vdc between the two legs of the main 450vdc FILTER CAP?

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

Also need good clear pictures of the inverter transformer board, SHOPJIIMY does not have any info on this SAMSUNG LE32D400E1W.

[YiannisQ]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

between the two legs of the main 450vdc filter cap i measure 390Volt DC

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

Good to the PFC Voltage booster is working.
Just to be sure, if you look at the front or at the back of the TV in the dark room, do you see the backlights even flash on for seconds?
I am able to find good pictures at shopjimmy.
Samsung LJ97-03461A (SST320_4UA01) Backlight Inverter.
Pictures provided by shopjimmy.

[YiannisQ]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

no there is nothing

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

some more measurements that i take
first the name of pin then the voltage in standby and on power

B13V---> 0.0V------- 12.86
B5V----> 0.0 ---------5.27
P_DIM--->0.0 ----------0.8--------------CN802
BLU------>0.0----------5.14
A5V----->5.26 ----------5.26
PS_ON-->0.0 -----------3.53



LD---->0.0----------11.50
VCC-->0.0-----------12.80--------------CNI801
CNT_PRT-->0.0--------12.2
OVP--->0.0-----------0.0

What dcv do you have on PIN 3 (LOW FET) and PIN 1 (HIGH FET)?

[YiannisQ]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

with the inverter plug in or out?
and the ground i put it on the - of the filter capasitor or on the ground of inverter?

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

with the inverter plug in or out?
and the ground i put it on the - of the filter capasitor or on the ground of inverter?

Yes, the inverter transformer board plugged in, the gnd for the meter will be the negative leg of the main filter cap in the primary side.

[budm]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

BTW, looking at the diagram (seems to match your board) in post #8, I wonder if the BL-ON gets all the way to pin 16 (EN) of the IC UI801 (SEM2106).
Also see if you do have VCC at pin 14. Use chassis for the GND ref for these two measurements.

[YiannisQ]

Re: SAMSUNG LE32D400E1W - No Power to Backlight

Unfortunately the voltage is dropping when i put the meter
the highest voltage that i measure in both was 9 volt dc and dropps to 0.670volts
I don't how it is.....I also pull out the inveter and i measure the same thing