vizio 42" lcd power board issue

[nukid]

Hi, I have been searching the web for answers to my problem. I was given a vizio vx42L lcd tv that previous owner said made a little pop or click and then it would not come on.

I checked it and found the fuse blown so I replaced that and as soon as I plugged the power cord in it it flashed/smoked, and popped. I looked the power board over and found the fuse still good but a blown resister near the main transformer. I have a pic as good as I could take, to show the smoky board and the resistor culprit. Oh, the resistor and the burn mark is near center to left of the blue thing.

Question, could the resistor be bad alone, or might there be a worse case situation? is it cheaper to just replace the power board? I have a dynex 42" lcd with no screen, does anything interchange with this set? And how cheap can I replace stuff...I am on very limited budget, part time work.
Any help, suggestions, ideas?
Jim

[budm]

Re: vizio 42" lcd power board issue

The resistor is in the circuit to limit the current flow through the circuit. In your case, it burnt up because the device (MOSFET, Diode, transistor, etc.) it is connected to is shorted out. You can try troubleshooting it down to component level or replace the whole module.
I do not know your experience in troubleshooting, and more likely you will not have the diagram for this power supply, so if you want to fix it, we will need good clear pictures of both sides of the board.
Replacement board is about $65.
http://www.shopjimmy.com/catalogsear...a+power+supply

[nukid]

Re: vizio 42" lcd power board issue

I will take the pictures...I cannot get any power to the board, not that I know about. I have only a multimeter, and limited experience of soldering. My dad was the technician. maybe I can find a replacement board, but I still will try to keep this cheap as I can and work with you. thanks.

[nukid]

Re: vizio 42" lcd power board issue

now for the big question...I have a 42" lcd dynex tv...same year but the screen was broken. Is it possible the 42" screen from this vizio will work as a replacement panel for the Dynex? I thought I had heard there were only a couple of lcd panel manufacturers. I am hoping, if anyone knows.

[Mr Bill]

Re: vizio 42" lcd power board issue

now for the big question...I have a 42" lcd dynex tv...same year but the screen was broken. Is it possible the 42" screen from this vizio will work as a replacement panel for the Dynex? I thought I had heard there were only a couple of lcd panel manufacturers. I am hoping, if anyone knows.

Look at the stickers on the back of each panel and see if they are the same.

[nukid]

Re: vizio 42" lcd power board issue

this is what i get when I open the vizio tv...I think it is a lg model LC420WX7..is that the lcd panel number? I will go get the other dynex tv and check it out too.

[Mr Bill]

Re: vizio 42" lcd power board issue

Yep, it's a LC420WX7(SL)(A1)

If the panels don't match you could sell dynex boards on ebay and then get a power supply for your vizio.

[nukid]

Re: vizio 42" lcd power board issue

Well, they don't match....grrr...but was gonna throw it away..so I will advertise on ebay. Thanks for suggestion.

[nukid]

Re: vizio 42" lcd power board issue

Another ?, where can I get a schematic so I can find what specs on resistor that blew and maybe the components in line with it that may have gone bad. And how does one check a transisitor? is it like two diodes hooked opposite to each other? been many years since my dad let me build from schematics and explained some basics of electronics back in the tube era.

[Mr Bill]

Re: vizio 42" lcd power board issue

Finding a schematc for your power supply is going to be tough. Most service manuals don't cover the power supply or it's deleted. But you might get lucky doing a google search. I usually check transistors for shorts with my meter in the ohm setting.

[nukid]

Re: vizio 42" lcd power board issue

do you check each side lead with the center lead?

[infringer]

Re: vizio 42" lcd power board issue

Check a transistor --> http://www.youtube.com/watch?v=REW2lF0sb74

How to determine resistor values --> http://www.youtube.com/watch?v=SjlnW5g9np4

[Mr Bill]

Re: vizio 42" lcd power board issue

if it's a 3 pin i would check pins 1-2, 1-3, 2-3. Post a picture and the numbers on it if your still unsure.

[nukid]

Re: vizio 42" lcd power board issue

I will check this tomorrow and also go back and check the ballast on my Samsung 3d dlp which won't light and has all three lights on front flash. That will be some fun. I have 2 tvs that should be awesome for free and I can't afford to fix either one...now aint that a trip. thanks for the info so far.

[nukid]

Re: vizio 42" lcd power board issue

Well, I ordered a power supply off ebay, hope by friday to put it in. Will let you know if it works. Also, anyone know how to isolate issue with a Samsung dlp if the issue is ballast board or otherwise? I checked voltage to the ballast and it is in range. but the little thing that lights when the ballast fires doesn't do anything and I don't hear the ballast firing up. Put a new bulb in and I don't know how to check the old bulb, IF it is bad. I don't have the money right now to order a ballast just to make sure.

[nukid]

Re: vizio 42" lcd power board issue

well, I put in a board I bought from ebay and plugged it in...no sparks at least. but no power either. It does nothing. I guess I gotta check voltages somewhere now, huh? Moving this weekend so it may wait till I have moved. but...where do I check? thanks for all the insight so far.
Jim

[budm]

Re: vizio 42" lcd power board issue

You need to see if it is at least putting out standby 5VDC.

[nukid]

Re: vizio 42" lcd power board issue

where do I check the 5 volts at? I do know that there are no lights anywhere. I tried to check the 24 and 12 volt pins but got zero. supposed to be a good board, but who knows from ebay.

[IamCanadian]

Re: vizio 42" lcd power board issue

if no lights you are prob not getting 5v stb,
Using the chassis as a ground just check each pin for dc volts. 5v stb should always be on.

It may even say on the PS?

[nukid]

Re: vizio 42" lcd power board issue

well, I just checked and found I do have 5 volts at the pins on one of the ps plugs going out to the main board. Only 4 pins have 5.1 volts, but no other pins have any power at all.??? now what?