Westinghouse LTV32W4 HDC no backlight

[eagle00799]

I have this this lcd tv that has sound and image but no backlight. I have read some posts about the inverter and some about the backlight being bad. I have checked the voltages on the 2 connections going to the inverter and if someone knows if these look good or bad can you please advise?[LIST]
Connection 1, pins 1-5 24.8
pins 6-10 are ground
Connection 2, pins 1-5 24.8
pins 6-8 ground
pin 9-SEL 00.0
pin 10 E-PWM .7
pin 11 1-Pwm 48. mv
pin 12 BLON 28.2
Here are a few pics of the boards.

[tom66]

Re: Westinghouse LTV32W4 HDC no backlight

Under the plastic shield on the left hand side is the inverter... looks like you need to take the frame off to get it, but there is usually a fuse on the inverter board.

[eagle00799]

Re: Westinghouse LTV32W4 HDC no backlight

I get 24.8 at both fuses.

[retiredcaps]

Re: Westinghouse LTV32W4 HDC no backlight

1) You have 8 ICs on the inverter board (3 pin leg). What is the part number?

2) Do you even see a brief flash of the backlight?

3) Is there a part number of the inverter transformers?

[eagle00799]

Re: Westinghouse LTV32W4 HDC no backlight

1)There are 2 different part numbers on the 8 IC's, IC number 1,3,6 and 8 are D454 BE5Z1B and IC's 2,4,5 and 7 are D413 BE652Z.
2) I get no flash at all from the backlight.
3) The part number for the transformers is like this, T51 0038 21257 0611 01 2 K

[retiredcaps]

Re: Westinghouse LTV32W4 HDC no backlight

1)There are 2 different part numbers on the 8 IC's, IC number 1,3,6 and 8 are D454 BE5Z1B and IC's 2,4,5 and 7 are D413 BE652Z.

See if the mosfets are shorted between G-S, G-D, and D-S.

http://pdf1.alldatasheet.com/datashe...D/AOD454L.html

3) The part number for the transformers is like this, T51 0038 21257 0611 01 2 K

Check the resistance between S1 and S2 for all of them. List all your measurements as they should be within 3% of each other. They should be around 1K ohm according to

http://www.lcdparts.net/TransformerD...ProductID=2817

[budm]

Re: Westinghouse LTV32W4 HDC no backlight

Can I get closed up pictures in the two areas? CMO Inverter usually has another small black fuse that looks like a surface mount resistor for the PWM IC section.
The two fuses you checked, are they labeled with F1, F2?

[eagle00799]

Re: Westinghouse LTV32W4 HDC no backlight

Budm, The 2 i checked where f2 and f3 then i checked f4 and f5 which are real small they are on each side of f2 and f3, F1 i found by the cn2 and it has a 20 stamped on it. i get 24.8 on one side and 0 on the other side.

[eagle00799]

Re: Westinghouse LTV32W4 HDC no backlight

The mosfets seem to be same on the D454's and the same on the D413's and the transformers have a high reading of .960k and a low of .939k

[Mr Bill]

Re: Westinghouse LTV32W4 HDC no backlight

Budm, The 2 i checked where f2 and f3 then i checked f4 and f5 which are real small they are on each side of f2 and f3, F1 i found by the cn2 and it has a 20 stamped on it. i get 24.8 on one side and 0 on the other side.

Have you checked F1? If your getting 24v on the one side but 0 on the other would indicate it is open.

[eagle00799]

Re: Westinghouse LTV32W4 HDC no backlight

so can F1 just blow for no reason or did something make it blow?

[budm]

Re: Westinghouse LTV32W4 HDC no backlight

That is the common failure for this fuse for the PWM circuits in CMO inverter board, that is always the first fuse I check. I replace a lot of them before and never come back for repair again, it can due to inrush current. There should be current and voltage rating close to this fuse. You can put you meter in DC current mode and put the two probes on each end of the fuse, then take the reading and double up for the fuse value.

[eagle00799]

Re: Westinghouse LTV32W4 HDC no backlight

so to order a new fuse does the 20 that is stamped on it mean 20amp? and it is a 24 volt fuse? i see no current and voltage rating near by for this fuse. to get the Value do i turn the power on and put the probe to each end?

[budm]

Re: Westinghouse LTV32W4 HDC no backlight

I am afraid you may slip the probes, so, do you have any 1 Ohm 1/4 w or 1/2 Watt resistor that you can solder in place of the fuse, then you can take the voltage reading across the resistor to determine the current?

[eagle00799]

Re: Westinghouse LTV32W4 HDC no backlight

no resistors here and my local repairman wont return my call, i left him a message asking if he could solder in a new fuse. I might have to put this on hold till i get properly equipt.

[budm]

Re: Westinghouse LTV32W4 HDC no backlight

If I remember correctly, I use 1A LITTLEFUSE PICO II series through hole fuse.
Solder one end of the fuse to VBL PIN 1, 2, 3, or 4 of CN2 another end is soldered to top end of C11. No need to remove the old fuse since it is blown any way.

[lilmonk3]

Re: Westinghouse LTV32W4 HDC no backlight

If I remember correctly, I use 1A LITTLEFUSE PICO II series through hole fuse.
Solder one end of the fuse to VBL PIN 1, 2, 3, or 4 of CN2 another end is soldered to top end of C11. No need to remove the old fuse since it is blown any way.

Budm.. Would you happen to have a picture of this mod?

[budm]

Re: Westinghouse LTV32W4 HDC no backlight

I cannot find my pictures, the TV I took the pictures is not Westinghouse but it uses the same inverter board, and I have 1000's of pictures I do not remember which brand it was. Is the board the same one as shown in post13?
See picture I made, use insulation such as tape under the left leg.