Westinghouse DWM50F3G1

[Sikora]

Hello all. I am new to the site and am trying to get some help. I am working on the above TV. I am getting the blue power light to come on when turning it on, but not getting the led's to come on. So far I have tried different PS and Main. Also have another set of lights. I am trying to figure out what the LED output voltage should be coming off of the PS. I'm getting 24.6V on the positive output but the strip has 12 LED's so I would think I should be getting 36V, or am I wrong. I was assuming they were all 3V led's or are some using 2V? Anyway when I check voltage after each led on the strip it drops 2V each. Any help would be greatly appreciated. Thanks.

[budm]

Re: Westinghouse DWM50F3G1

We need good clear pictures of the power supply/LED driver board top and bottom side and especially around the LED connector..
The LED strips may be connected in series to form one long string or they may be driven by individual driver for each strip, so we need to find out how they are driven first.

[dick_barton]

Re: Westinghouse DWM50F3G1

Looking at the back of the power supply board I think the 5 sets of leds are all connected in series. Definately not individually connected to supplies. So if 3V leds = 180V. You can confirm that all the leds are in series by checking the underside of your board.

Edit
Courtesy of Shopjimmy

[vinceroger69]

Re: Westinghouse DWM50F3G1

Looking at the back of the power supply board I think the 5 sets of leds are all connected in series. Definately not individually connected to supplies. So if 3V leds = 180V. You can confirm that all the leds are in series by checking the underside of your board.

Edit
Courtesy of Shopjimmy

What proxy site are you using to use shopjimmy ive tried most proxy sites none seem to work.

[Sikora]

Re: Westinghouse DWM50F3G1

Here are better pics of PS

[dick_barton]

Re: Westinghouse DWM50F3G1

What proxy site are you using to use shopjimmy ive tried most proxy sites none seem to work.

I use the following proxy server for access. You can enable / disable it at will.

http://www.anonymox.net/en

[dick_barton]

Re: Westinghouse DWM50F3G1

Here are better pics of PS

So how many strips are in series and how many series in total.

[vinceroger69]

Re: Westinghouse DWM50F3G1

I use the following proxy server for access. You can enable / disable it at will.

http://www.anonymox.net/en

Thanks that works fine.

[dick_barton]

Re: Westinghouse DWM50F3G1

Glad to help

[Sikora]

Re: Westinghouse DWM50F3G1

There is a total of 5 strips with 12 LED's on each. I check the voltage at the beginning of the strip and get 24.6 then after each led 22.6, 20.5, 18.4, 16.3, 14.0, 12.0, 10.0, 8.1, 6.0, 4.1, 2.0, 0.00

[budm]

Re: Westinghouse DWM50F3G1

L+ is the Anode of the first strip which is fed by the Boost converter circuit, you need to leave the red probe on that L+ pin, black probe on the chassis then turn the TV on to see how high the Voltage jumps up to and then settle down at lower Voltage.

[dick_barton]

Re: Westinghouse DWM50F3G1

The led connectors appear to be connected to each other on the underside of the board.
Can you use your meter set to ohms and check if Led1 connector has one of its pins connected to one of the pins on Led2. Led 2 has one of its pins connected to one of the pins on Led3 connector......etc

[budm]

Re: Westinghouse DWM50F3G1

Westinghouse MIP550D-5TH Power Supply.
Is this your exact board? It does not have the L+ pin as shown on the bottom side of the board per pix by DB.

[dick_barton]

Re: Westinghouse DWM50F3G1

So have I been looking at the wrong power supply board. If Budm is correct then please ignore my previous comments which will be steering you down the wrong path.

[budm]

Re: Westinghouse DWM50F3G1

LED strings are connected in parallel per SJ pictures.

[budm]

Re: Westinghouse DWM50F3G1

LED driver circuit, from the look of it, the power supply is not putting out enough Voltage to drive 12-LED string based on the dcv reported by OP.
The op should be able to have one LED string connected one at a time to see if it will even light up one string, LED strings are connected in parallel. Also need to check the Voltage without any LED string attached.
The low Voltage can be due to problem in the primary drive side or in the secondary side. More in-depth troubleshooting will be required to get down to the component level.

[Sikora]

Re: Westinghouse DWM50F3G1

Will not light up connecting only one set. Also when checking voltage with all disconnected I am getting the same 24.6V after it comes on and is a volt or two lower for a short time (I assume that would be the log screen trying to come on).

[budm]

Re: Westinghouse DWM50F3G1

24V will be too low.
What is the DCV rating of the caps EC20, EC21?
The hard part now will be figuring out what is causing low output Voltage.
the primary drive side is doen by Q15, IC3, startup/running caps EC2, EC3.
D4 on the heatsink is the rectifier on the secondary side which you should check.
You may try heating the board in those area with hairdryer.
We also need to make sure we have boosted Voltage on the main cap EC5, so you should check the DCV between the two legs of the cap to see what you have.

[budm]

Re: Westinghouse DWM50F3G1

One thing just dawn on me, did you check to see if you do have DCV at CON4 BLK/ON pin?

[budm]

Re: Westinghouse DWM50F3G1

BTW: per post #1" So far I have tried different PS and Main"
Are they know good boards?
Also, the LED strips, are they the one for this LCD panel?