Dead Vizio VL 420M

[Tayninh55]

Re: Dead Vizio VL 420M

No opinions on my last question?

[budm]

Re: Dead Vizio VL 420M

https://www.badcaps.net/forum/showth...893#post533893
This is what the OP has done.

[Tayninh55]

Re: Dead Vizio VL 420M

Ok,,,,just to be sure,,,,,,the only thing I can see on the transistor is a “QZ”. It doesn't show the symbol for the transistor on the board so I can tell which way the voltage is flowing. I can tell that this is a “surface mounted transistor” or “SOT” so I am assuming that the “stand alone pin” (D), is not the Base, but the Collector, and the left pin (G) would be the Base, and the right pin (S) the emitter as noted on the board. I would be measuring the voltage between the emitter and base first, and then the voltage between the emitter and collector.
Is this correct?

[budm]

Re: Dead Vizio VL 420M

You need to tell us from tracing the board as to how the ps-on pin goes to what resistors, which pin of the suspect transistors, etc. If you look at the other link, the OP at least tell me how the resistors are connected.
As you can see, one end of R11 is connected to pin 1 of the connector, the other end is connected to ???? and then to ?????

[Tayninh55]

Re: Dead Vizio VL 420M

Well Bud, it's been quite an experience,,,I really hate to admit it,,,,,but YOU WERE RIGHT! I don't have enough knowledge, or experience to do this. I tried, I have a big lighted magnifying Lamp that I used previously for "woodcarving", but even with that I can't see the resistors well enough to determine their value. I also can't follow the printed circuit board (with no completely connecting lines) well enough to be able to tell exactly where they go. I tried following them by testing for resistance, but don't feel I did a very good job. I'm attaching the pictures anyway (Which I know is not what you asked for) so you can see the "mess I made". I guess I'll just try to find a good, used MAIN BOARD if I can, and replace the board. I was figuring on replacing a component, but I know now that "it ain't going to happen". Not sure I could even replace a resistor, as small as they are. I appreciate all the help you and Cap gave me over the course of this "tiring" experience! Thanks a lot!
Don

[CapLeaker]

Re: Dead Vizio VL 420M

problems on the main board can be tricky and it is not for everybody to repair on that level. At least you got some exposure into fixing TV's. Hope you had at least some fun... Tracing if you have a schematic isn't that bad, but once you have to draw one yourself, then it gets really interesting.

[budm]

Re: Dead Vizio VL 420M

Since the only only signal you are not getting is the ps-on, but you can force it on using resistor, if I were you I would leave the resistor in place (but no wire going back to the main board) to use the TV that is connected to switched outlet strip that you can kill the power to the TV. Use it like that for now until the price of the main board come down.
Or hook up a switch to the resistor for force on and off with a switch.

[Tayninh55]

Re: Dead Vizio VL 420M

Ok, thanks to both of you! Bud, you're saying that I could put the resistor back in GOING FROM the +5VSB (pin #1) of the 12 pin connector AND TO (pin #5) ON_OFF_INVERTER on the 6 pin connector,,,,,,,,,,then cut the wire on #12 pin, the PS_ON pin? It would be safe and ok to use it that way with the switched outlet? That will sound good to them and I'm sure they wouldn't mind doing that until I can get a board! Thanks again!

[CapLeaker]

Re: Dead Vizio VL 420M

Yep. But I would do that only with the PSon pin first. You always can add the BLon.

[Tayninh55]

Re: Dead Vizio VL 420M

Remember Cap, don't give me too much information at one time! You are talking about soldering the TWO resistors back in? Yes, solder 1K resistor back between +5vbs AND PS_ON. Cut wire that runs between PS_ON on power board and main board.

I also have to solder the second 1K resistor back in between +5vsb and ON_OFF INVERTER?

Since this is a tv in their "rec room", they probably wouldn't care if we replaced the board or not, as long as it would work and be safe with the switched outlet. So, I could re-assemble it and give it back to them the way it is.

[CapLeaker]

Re: Dead Vizio VL 420M

Cut the PSON wire that goes between the main board and the power supply. Cut it in a way so you can solder it back together some day.

I would solder a piece of wire on the 5v STBY rail on the bottom of the power supply and solder that end to a switch. Then solder another piece of wire with a 1k resistor between the switch and the PSON wire (the one you just cut) on the power supply side. See if that works.

[Tayninh55]

Re: Dead Vizio VL 420M

Hey Bud and Cap,,,,,thought I'd let you know that I got her "fired up and working"! I only put "one resistor" back in, between the +5vbs and the PS_ON. I also "cut the wire" on the PS_ON between the two boards like you said to do. Doesn't need a switch, at least not so far! I plugged it in and the yellow logo came on,,,,,,hit the "power button" on the remote and the logo turns white, and the tv comes on. Hit the "power button" again and the tv goes off, with the yellow logo returning. The back lights are also going off when you turn the "power button" off on the remote control. Seems like it is working just the way it is supposed too! "No switch" on with the 1K resistor, and "without a switched outlet". Going to tell them to watch it that way until "something else" goes wrong! Thanks again!

[CapLeaker]

Re: Dead Vizio VL 420M

Thanks for the follow up!

[budm]

Re: Dead Vizio VL 420M

Hey Bud and Cap,,,,,thought I'd let you know that I got her "fired up and working"! I only put "one resistor" back in, between the +5vbs and the PS_ON. I also "cut the wire" on the PS_ON between the two boards like you said to do. Doesn't need a switch, at least not so far! I plugged it in and the yellow logo came on,,,,,,hit the "power button" on the remote and the logo turns white, and the tv comes on. Hit the "power button" again and the tv goes off, with the yellow logo returning. The back lights are also going off when you turn the "power button" off on the remote control. Seems like it is working just the way it is supposed too! "No switch" on with the 1K resistor, and "without a switched outlet". Going to tell them to watch it that way until "something else" goes wrong! Thanks again!

Not really, with that resistor in place, the whole power supply is fully on 24/7 which is not a good thing even when the power switch is deactivated instead of just having the STBY power supply running only, so the TV will still draw quite a bit of power when it is off.

[Tayninh55]

Re: Dead Vizio VL 420M

Bud, Ok,,,,,,,,,,didn't realize that. I'll tell them to use the switchable outlet! Thanks again!