VIZIO VX32L power supply running VX37L television

[ZnsaneRyder]

VX37L is the tv I am repairing
VX32L is the PARTS TV

I was having trouble with 5V standby keeping voltage on the VX37L with the mainboard connected, so I suspected mainboard was pulling down the 5V rail. Tried Mainboard from VX32L, same symptom, so not the mainboard. Without the Mainboard plugged in, I get full 5V standby voltage.

I connected the VX32L power supply (PSU) inside the VX37L TV, and it runs fine. I get image on screen, and backlights, and everything. I am heat-testing the power supply to see if it is capable of running the larger set.

BOTH PSU state 3A input, but ONLY the VX37L PSU states the amperage of the individual outputs, not the PSU from the VX32L.

Only other issue, is screw holes don't line up, but I can adapt that.

I still trying to repair the PSU for the VX37L and cannot find the fault as of yet.......

Is it safe to use the 32 inch PSU for the 37?

[ZnsaneRyder]

Re: VIZIO VX32L power supply running VX37L television

So far the heatsinks are about 100-110F but the MBR30H100CT for the 24V rail (backlight) is running 146F so it seems to be warm, but not running too hot.

The output heatsink on the 37 inch PSU is smaller, go figure, so it seems the 32 inch PSU will run this TV?

Any input? I'm about to put this set back together and make adaptor mounts for the PSU to bolt in.

[SLK001]

Re: VIZIO VX32L power supply running VX37L television

Believe me, if the manufacturer thought that he could run the 37" TV off the 32" power supply, he would have done it.

Best to get the properly sized power supply.

[dick_barton]

Re: VIZIO VX32L power supply running VX37L television

From the checks already carried out it appears as thought he original psu is at fault.

I would check the caps on the psu for high ESR or change in capacitance value.
They can all look good but that is no guarentee that they are.

[ZnsaneRyder]

Re: VIZIO VX32L power supply running VX37L television

Thanks, all the caps check good, I will keep checking.

I feel silly for starting the thread, without better comparing the two units first. For some reason, the 32 inch power supply uses a higher rated mosfet, diode, larger transformer, slightly more heatsinking, and more caps? WTF? This makes it obvious that the 32 inch is actually the better supply. Both are rated same input draw from the wall as well.

WTF, why would Visio use a better PSU in the 32 inch? Maybe they were cutting costs in later, lesser selling models?

Regardless, I will use the 32 inch supply. I added an extra 1000uf 35V cap, and put a healthy amount of thermal compound on the plates that bolt to the heatsinks, and that made it run somewhat cooler. I will do some temp checks when it warms up again.

[ZnsaneRyder]

Re: VIZIO VX32L power supply running VX37L television

(On the broken 37inch supply) I am only getting 170V on the Main Cap after the PFC. The PS does not turn on, so the PFC doesn't rise. Even though I am using the 32 inch supply, I am still trying to repair the 37 inch psu. Something in the 24/12v section may be bad, but I haven't found it yet.

[ZnsaneRyder]

Re: VIZIO VX32L power supply running VX37L television

Regardless, I will use the 32 inch supply. I added an extra 1000uf 35V cap, and put a healthy amount of thermal compound on the plates that bolt to the heatsinks, and that made it run somewhat cooler. I will do some temp checks when it warms up again.

Hottest part, the 30H100, now runs only 134F, quite a difference after adding the thermal compound to the heat sink plates!