westinghouse DWM551Y1 no power

[taft1957]

This set is completely dead, just solid red standby light. I replaced power supply, main board, and what do they call that small board with the eeprom on it? still no fix. Anyone have problems like this? anyone have a schematic for this tv, or just a fix, or a suggestion.

Thanks
Taft

[taft1957]

Re: westinghouse DWM551Y1 no power

does anyone have a service manual for this tv?

[martyparish]

Re: westinghouse DWM551Y1 no power

Can you upload pictures?

Did you test the voltages on the power supply(old and new)?

First thing I would check, is the STBY voltage correct. Then you can test the PSON lead to see if it changes when you hit power button.

[taft1957]

Re: westinghouse DWM551Y1 no power

I may have been thrown a curveball by receiving a defective new power supply. Even after replacing the main, and eeprom board? i just jumped the power on to 5 volts standby, and the 12 volt to backlight on Voltages were fluctuating up and down from 12 volts to 5 volts very erratic. I lifted TR1338 VLD-LEDTV1251-L7 that is the number on the part. not a location number. After I lifted it voltages all stabilized. I think I found my problem. anyone know where I can buy this part?

Thanks
Taft

[budm]

Re: westinghouse DWM551Y1 no power

'TR1338 VLD-LEDTV1251-L7 ' we have no idea what that is. Where are the pictures? It sure does not sound like P/N of components to me.
Some kind of transformer? Inductor? so when you lift it the drive circuit that drive this part may be bad so when you disconnected it the circuit no linger draw the current, so it may not be this part that is bad but the components that drive this part may be bad.
We cannot do much until we get to see good clear pictures of what we are dealing with first.

[budm]

Re: westinghouse DWM551Y1 no power

Is this your board?
http://www.shopjimmy.com/seiki-890-p...upply-unit.htm

Seiki/Element 890-PF0-5501 Power Supply.

TR1338 VLD-LEDTV1251-L7, L7 looks to be designator for the part.

Model number on the barcode sticker is 'VLD-LEDTV1251????'
P/N for the board on the barcode sticker?

[taft1957]

Re: westinghouse DWM551Y1 no power

Yes that is my board?

[taft1957]

Re: westinghouse DWM551Y1 no power

I was hoping to buy the part and not the whole board.

[budm]

Re: westinghouse DWM551Y1 no power

So which part that you lifted off the board?

[taft1957]

Re: westinghouse DWM551Y1 no power

here are some pictures

[dick_barton]

Re: westinghouse DWM551Y1 no power

Hello Taft1957,
Your first post says you replaced the power supply so can't you take the transformer from the defunct psu?

[budm]

Re: westinghouse DWM551Y1 no power

That is not transformer, that is the inductor for the Boost converter for the LED sriver circuit, so when you remove it it is no longer connected to the power MOSFET that is used for driving the inductor. It will also show low DCR value which is normal.

[budm]

Re: westinghouse DWM551Y1 no power

Any Straight shot pictures of the bottom side of the board without the insulator sheet in place?

[taft1957]

Re: westinghouse DWM551Y1 no power

Stupid me, I will test that as an inductor. It might not be my problem.

[taft1957]

Re: westinghouse DWM551Y1 no power

Glad I didn't throw it away. That means I am back to square one on this set. If that part isn't bad. Then the new power supply was probably OK. As I said in one of my first post. I replaced the power supply, main board, and FRC board, mistaking it for a eprom board. Since none of those boards made the repair, and I thought I had found a bad transformer on the original board. I sent all those boards back. How much voltage am I looking for to light the led's? When you jump 5 volts to power supply on, and 12 volt to backlight on, if there is nothing wrong with the power supply or the main board, or the led's then the backlight should light, right?

[taft1957]

Re: westinghouse DWM551Y1 no power

The inductor was fine. I found a bad fet and replaced it. I jumped the 5 volts to power on, and the 12 volts to backlight on. All voltages came back steady 5 volts and a steady 12 volts. However, at the led + and led - the voltage seems high and is fluctuating from 172 to 175 on both sides. what regulates that voltage?

[dick_barton]

Re: westinghouse DWM551Y1 no power

However, at the led + and led - the voltage seems high and is fluctuating from 172 to 175 on both sides. what regulates that voltage?

Is the backlight working now?

[taft1957]

Re: westinghouse DWM551Y1 no power

where can I buy a portable led driver to test a led backlight?

[CapLeaker]

Re: westinghouse DWM551Y1 no power

I power mine on a CV CC variable bench / lab PSU.

[budm]

Re: westinghouse DWM551Y1 no power

We need to see the straight shot pictures of the bottom side of the board to see if it has one or more than one LED driver circuits.