Vizio L32 tv power supply problem

yeomp · Guest

I just opened up a Vizio L32 LCD tv to fix the power supply. The fuse was blown and so I replaced it. Now, I get a 5.1v output of v1 but v2 and v3 are both dead. Also it looks like the heat-sink is hot, it is reading the same 5.1 volts from output ground.

Debugging this has been a pain, anyone else have any insight?

minnie · Joined: 18 Aug 2005 Posts: 2880 Location: Hell

These sets are designed for board level repair. What's the model?

yeomp · Guest

The model number on the power supply board is:
0469D03
Is there any way to get a replacement board? I was thinking of grabbing a broken screen off ebay and switching the boards, but if there is another way...

minnie · Joined: 18 Aug 2005 Posts: 2880 Location: Hell

Guest · Posted: Thu Feb 22, 2007 2:46 am Post subject:

Set Model:
L32HDTV10A

ResurrecTek · Joined: 21 Oct 2006 Posts: 9

Hi, did you ever get resolution to your problem? I have repaired several of these power supplies.

Check the big FET (Q1), it is a "buck switching" driver, good chance it may be shorted. The big cap (C7) may need replaced also, look for a bulged top or signs of anything leaking out it it. (the top should be perfectly flat or slightly "caved in-looking") Check the other caps for visual signes of bulging or leakage.

There are four parts to the power supply.

There is a 5v "housekeeping" power supply, down around through T1 and out, PWM is on the bottom of the board under that section.

That power supply runs the processor board and the processor monitors the power button and the remove control sensor.

When the power button is pressed, the processor board pulls high the "remote" pin on the power supply CN3 connector.

When this pin goes high, several things happen on the board.

Normally the hi-side DC bus is about 180vdc across cap C1. When the remote pin goes high, Q1 starts getting pulsed via the 8-pin SMT chip under L1 and raises the voltage on L1 from 180vdc to about 375vdc.

Also, the two other switchers kick in, through T2 and T3 and across, their PWM's are under the board.

If all of this does not happen, the board does not come up.

Good luck, contact me if I can help more.

Also, I need 2 logic boards for L32's if anyone is tuned in Smile

Regards,

Mike

Justmanuals · Joined: 21 Aug 2004 Posts: 1948

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Guest · Posted: Sat May 05, 2007 4:45 pm Post subject:

Thanks for the lead.

Mike

yeomps · Guest

RTek,
thanks for the help. I had to put this one on the shelf for a bit. My current problem is that the power supply does not seem to respond to the power button. It doesn't look like the 'remote' is going high. Also, it looks like one of the heatsinks is hot. It seems to be at 6volts. It that right?

Thanks

Alex30093 · Guest

I don't really play with capacitors but I do try to fix some electronics, mostly computers. I have the Vizio L32 with the dead power. I opened it up and removed the power board cover and I can see a spot where it has a burn mark as if the screen shorted out something with three prongs.

Can these boards be refurbished? I saw one for 85 including a core charge vancebaldwin.com. I am not in a huge hurry but it would be cool to have fixed. Alex30093_at_yahoo_com

thx
-Alex