Vizio V042L Completely dead!

[XmouseX]

Re: Vizio V042L Completely dead!

So all three of these Mosfets on the secondary are shorted from Gate to Source... I never tested these, because I thought the problem was in the Primary...

[XmouseX]

Re: Vizio V042L Completely dead!

Maybe I am testing them wrong...

[budm]

Re: Vizio V042L Completely dead!

OK, your pictures are not in focus, it looks like the camera was not holding steady. So I went to shopjimmy and got pictures from there instead.
So check the resistor value of R919.
Using Ohm mode and check the resistance reading (with probes both directions) of ZD903, D904.
Report the readings of all three components, make sure to report if the readings are in Ohms, K Ohms, or M Ohms.

Power supply:
http://www.shopjimmy.com/vizio-0500-...wer-supply.htm

[XmouseX]

Re: Vizio V042L Completely dead!

R919 says 4.7 Ohms on the resistor and it measured 4.8 Ohms

ZD903 gave no reading one way and 6 Mega Ohms the other way

D904 gave no reading one way and 6 Mega Ohms the other way

Sorry about the pics. Doing my best.

[budm]

Re: Vizio V042L Completely dead!

Here is the diagram. Check the fusible resistors R805A/B to see if there are open (high resistance).

[XmouseX]

Re: Vizio V042L Completely dead!

Both fusible resistors are good. It looks like my voltage is stopping at the transformers...

[budm]

Re: Vizio V042L Completely dead!

So check and see if you do have DC voltage between the negative leg of the main filter cap and pin 2 of the 5V STBYtransfomer T901.

[XmouseX]

Re: Vizio V042L Completely dead!

Just to make sure I am doing it correctly, do I ground the black probe and put my Pos probe on leg 2 of T901?

[XmouseX]

Re: Vizio V042L Completely dead!

102.8 Vdc on leg 2 of T901

[budm]

Re: Vizio V042L Completely dead!

Black probe on the negative leg of that large filter cap, that is the the ground ref. point for the primary side of the circuit you are checking. Make sure not to touch anything with your hands! I expect 160vdc.

[XmouseX]

Re: Vizio V042L Completely dead!

156.5 Vdc then when I did it the right way

[budm]

Re: Vizio V042L Completely dead!

OK, that mean the MOSFET is not being driven by the IC900. That can be due to bad IC or just bad C903 start/running cap. Try heating C903 with hair dryer for a few minutes to see if 5v will start up. What is the P/N of the IC900?

[XmouseX]

Re: Vizio V042L Completely dead!

I know C903 is good, because I replaced it already. IC900 P/N is 2A08N19 5531 ....very hard to read.

[XmouseX]

Re: Vizio V042L Completely dead!

I have been suspecting IC900, but was unsure on how to test it. The diagram you sent me was VERY helpful!

[XmouseX]

Re: Vizio V042L Completely dead!

The only 8 pin IC that size that I have is a 4407A..lol Cant seem to find anything on the part number from the other one

[budm]

Re: Vizio V042L Completely dead!

We do resistance reading between the Ground pin of the IC against all the other pins, but we need to find the spec sheet of that IC 900 first.

[XmouseX]

Re: Vizio V042L Completely dead!

Fuji Electronics FA5531 I think is a the IC we are looking for

[budm]

Re: Vizio V042L Completely dead!

Here is the spec sheet, the app notes circuit looks almost the same as I have drawn out.
https://cdn.badcaps-static.com/pdfs/...bccc47e3fa.pdf
So put meter in Ohm mode, black probe on pin4 (Gnd), then use the other probe on all other 7 pins to see what reading you get, report each resistance reading on each pin against pin4.