Voltage level on LCD power supply board.

[selldoor]

Re: Voltage level on LCD power supply board.

First thing is to test the glass fuse - please post resistance in ohms. Next Test would be on the Bridge rectifier but cant really tell where it is - is it on the short heat sink?. If you cant identify it go on to the next test which is for the DC voltage across the legs of the big cap. Very careful as high voltage and do not touch the heatsinks. Meter on 600 voltsDC observe polarity.Report voltage when its just plugged in and again when you press the power button.

Can you report on the white rectangular component mentioned earlier
any writing on it.

[dcavman]

Re: Voltage level on LCD power supply board.

Also the 5vdc stand by and 12vdc supplies are there when nothing but ac is hooked into it

[dcavman]

Re: Voltage level on LCD power supply board.

Already went through the basics fuse and diodes those white things are 3watt resistors they test out fine also

[selldoor]

Re: Voltage level on LCD power supply board.

Well thanks for that! - might be better if you tell us what you have done and what doesnt work instead of us guessing?

[dcavman]

Re: Voltage level on LCD power supply board.

Well my main consern is how to test that this pcb is working properly. Dont want to put time and money into somthing thats fine is there a way to test the main pcb in the unit and more pictures arpund two

[budm]

Re: Voltage level on LCD power supply board.

So from the info we have so far is that the TV is dead, but you do have 5V standby and the 12V, so then do you get any indicator lignt on the TV at all? That 5V is used to run the TV processor. The 12v is for the sound, the 24V is for the backlghts.
My question is that do you get sound and indicator lights but no backlights?
That Blue cap is for the 24V power supply section.
By the way, that large 450vdc cap should have 170Vdc on it when the TV is OFF, and about 400vdc whne the TV is turn on, it is part of the PFC circuits, please tell us if that is what you have.

[dcavman]

Re: Voltage level on LCD power supply board.

I get no response from the tv once plugged in i hear the innitial relay kick over but it stops there

[dcavman]

Re: Voltage level on LCD power supply board.

With just the ac that 450vdc cap hit 300+ not sure whar that tells us

[dcavman]

Re: Voltage level on LCD power supply board.

i hope these pictures may help a bit more like i said a previous owner may have taken it upon them selves to attempt fixing it not sure yet

[killian6pk]

Re: Voltage level on LCD power supply board.

i hope these pictures may help a bit more like i said a previous owner may have taken it upon them selves to attempt fixing it not sure yet

On the picture of the back those two larger round objects look like fuses. Are they plastic and do they have a amp and volt printed on them? Also on the bottom of the picture what is that wire thing soldered to the board? What are the connections the wire is connected to are they solder joints for something on the front of the board?

[dcavman]

Re: Voltage level on LCD power supply board.

The black things are spacers to keep the bottom from touching the tv metal shell i also repaired a trace with buss wire that is what i am guessing you are talking about yes they are for parts on the fron of the board

[killian6pk]

Re: Voltage level on LCD power supply board.

Ok, thought I could see numbers etc on round spacers. It would be a very funny place to put that type of fuse.

[dcavman]

Re: Voltage level on LCD power supply board.

The 12v and 5v supplies are immediate but the 24 takes a minute to come up and levels off around 25v

[budm]

Re: Voltage level on LCD power supply board.

Well that means the Main board does send out the PS_ON signal to turn on the PFC (large cap voltage goes up to 300+) and the 24V does turn on, so the main board does some what functioning.
The question will be is that do you see the backlights flash on at all? You may just have the backlght inverter problem, you should look at the screen in the darkened room to see any glow on the screen. So far you are getting all the voltages (5v, 12v, and 24V) like you should.

[dcavman]

Re: Voltage level on LCD power supply board.

I am getting power to the standby light but power button does nothing

[dcavman]

Re: Voltage level on LCD power supply board.

Press power it goesblue then back red

[selldoor]

Re: Voltage level on LCD power supply board.

With just the ac that 450vdc cap hit 300+ not sure whar that tells us

was your meter on ac or dc


EDIT and is 300+ 301V or 390V -it makes a difference

[budm]

Re: Voltage level on LCD power supply board.

Edited

[selldoor]

Re: Voltage level on LCD power supply board.

Much better pics - thanks.
On the top of the board two of the caps have small marks is that leakage? C918 and the green one nearest the end near where it says w817.
Also on left side middle there is a 7/8 legged component perhaps N901 - is the white dot just a paint dot or is it damage.

[budm]

Re: Voltage level on LCD power supply board.

What happen if you disconnecte the power cables to the backlight inverter boards, will the Indicator light stay green?