Westinghouse DW39F1Y1 no backlight...testing board

[pasta prime]

My TV powers on but there is no back-light. I can see the screen if I turn it at the right angle so I know its on but the back-light isn't coming on. I want to verify if its the board or the leds that are bad

I have included a picture of the board and have tested the LED plugs on the board. The two right plugs have 84 vdc on the red pin and the two left plugs have nothing. With the tv on or off same reading. Is this correct?

What else can I test and how?

[budm]

Re: Westinghouse DW39F1Y1 no backlight...testing board

85V is about right since the boosted converter filter cap C107 is rated at 100VDC.
You should remove the 4 LED FEMALE connector from the board and check the resistance of each pin of the female connector against the chassis to see if any one of them show resistance reading, lots of Westinghouse LED backlit TV has problem with wire insulation got cut and shorted to the chassis. Common problem also due to bad LEDs.
You can search the forum for that information.
Please also upload good clear pictures of the whole bottom side of the board.

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Thank you for the reply here is the back side of the board. There are no visible burnt lines or anything. All the caps look good. What connector are you talking about?

[budm]

Re: Westinghouse DW39F1Y1 no backlight...testing board

The LED connectors CON1 ~CON4.
Too bad that the LED driver board is mounted on top of the main power supply board so we cannot see the traces on the bottom side of the LED driver board to see how it works.

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

All are good so you think its the board?

[budm]

Re: Westinghouse DW39F1Y1 no backlight...testing board

You can disconnect all 4 connectors and check the Voltage on the + pins to see if two of the + still not show any voltages.
Right now I cannot tell if all 4 LEDs strings are connected in series to form on string or not, it not clear to me in the picture of the bottom side of the board.

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

The two + still show voltage with the connectors unplugged.

[budm]

Re: Westinghouse DW39F1Y1 no backlight...testing board

You may have to trace on how the 4 connectors pin are tied together to see if they are connected in one series, or two in series and then in parallel with another two that are in series.
I have a feeling that you have open LED on the LED string.

[Agent24]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Open LEDs do seem to be common on the forum here...

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Thanks a lot for the help. I'll do that and see what I can come up with.

[MagicSmoke]

Re: Westinghouse DW39F1Y1 no backlight...testing board

I can almost guarantee that there are shorted or open LED's in it. I repaired one of these last week. It is a pain in the butt to take the panel out without cracking it. Mine had 2 shorted one open.

The front bezel holds the glass to the plastic spacers on the chassis. It has to be panel up to take it apart.

Then the T-con boards are double sided taped to the chassis and have to come off with the panel. After the panel is removed the plastic panel spacers hold the diffuser and the white paper background to the chassis.

There are 2 or 3 different versions of strips used in these sets, so you will have to get the P/N off yours to replace.

BTW psu sits at 26v in stby then should jump to 85v or so before shutting off.

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Is there a take down video or anything? I don't wanna break anything.

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Got some more time to tear into this again and when testing the two middle led strips I get 65v the two outer have none.

Also, when I test the two middle strips it barely lights up the two outer leds.

So still the leds bad?

[Agent24]

Re: Westinghouse DW39F1Y1 no backlight...testing board

For some reason I can't view those photos. Only the preview works.

Weird. It works now....

[budm]

Re: Westinghouse DW39F1Y1 no backlight...testing board

So there are 4 strips? The problem is that we do not know (since I cannot see the traces on the bottom side of the board to see how the LED connectors are setup) if two strips are connected in series to form one long strip, same for the other two strips (connected in series) so it has two big long strips.
You may have to test each LED one by one.

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Yes its two strips per line. Are they just taped down with double sided tape or something?

[budm]

Re: Westinghouse DW39F1Y1 no backlight...testing board

You may want to read this thread:
https://www.badcaps.net/forum/showth...849#post537849

[pasta prime]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Thanks for that. I think I found the culprit. So one LED can make the rest not work because they are in series?

[budm]

Re: Westinghouse DW39F1Y1 no backlight...testing board

Thanks for that. I think I found the culprit. So one LED can make the rest not work because they are in series?

Yes.

[Bitgod]

Re: Westinghouse DW39F1Y1 no backlight...testing board

I have this same board and TV, what voltages am I supposed to EXPECT on all 4 CON # connectors?