Sony Vizo SV370XVT power supply not working.

[H-Man]

I have a Sony Vizo that does not turn on. The power supply, a DPS-201EP has a blown fuse (4 amp) and poking around with a multimeter shows that there is a short somewhere in the powersupply, or my multimeter needs a new battery (cheap harbor freight meter.) Not sure what to look for, but there is some discoloration on the PCB around some diodes that look to be intended to handle a lot of current. Part number Sony gives the power supply looks to be 0500-0507-0690.
Whot I do know: Multimeter reads near zero ohms on a transformer.
No visible bad caps.
Blown fuse.
Rectifier bridge good.
No burnt mosfets.

[drpj23]

Re: Sony Vizo SV370XVT power supply not working.

This is a Vizio, correct?
Anyways, the transformer will have parts that will measure shorted and that is normal but the transformer is rarely a failed part. I would check those 2 diodes for a short.

[awyatt2]

Re: Sony Vizo SV370XVT power supply not working.

check the mains cap for short after discharging it completly. you may have a fet shorted, or a diode shorted.if the fuse is blown you have a short somewhere closeby.

[H-Man]

Re: Sony Vizo SV370XVT power supply not working.

This is a Vizio, correct?
Anyways, the transformer will have parts that will measure shorted and that is normal but the transformer is rarely a failed part. I would check those 2 diodes for a short.

Yep, it is a vizio.

check the mains cap for short after discharging it completly. you may have a fet shorted, or a diode shorted.if the fuse is blown you have a short somewhere closeby.

I'll see if I can figure out the layout of the circuit, it helps me to figure out the problem if I have a schematic.

[H-Man]

Re: Sony Vizo SV370XVT power supply not working.

Update: One of the diodes was shorted. Not sure if it was a cause of failure or collateral damage, but I'm replacing both diodes. The diodes are MUR460, looks to be a 600v 4amp diode.
Clipped it out of the circuit to test it just to make sure, and yep, shorted.
Seeing if I can find a replacement locally so that I can get the TV off of my workbench.

[H-Man]

Re: Sony Vizo SV370XVT power supply not working.

Replaced diodes, fuse still blows.
I'm starting to suspect the mosfets.

[ben7]

Re: Sony Vizo SV370XVT power supply not working.

Replaced diodes, fuse still blows.
I'm starting to suspect the mosfets.

See if the diode is blown again.

Could you please get us some good pictures of the board, and point out where this diode that you found bad was located?

-Ben

[H-Man]

Re: Sony Vizo SV370XVT power supply not working.

I found the short: 2 mosfets labeled k10a60d.

[Hoblah]

Re: Sony Vizo SV370XVT power supply not working.

I am having this exact same issue as you. The fuse was blown and those two diodes on the board are shorted. Did replacing those MOSFETs & Diodes fix the problem? I am suspecting the exact same two MOSFETs as you say are shorted.

[budm]

Re: Sony Vizo SV370XVT power supply not working.

You have to watch out when the MOSFET blown up, the Drain and Gate could have shorted out and blown open later on which at the same time it will also take out the IC the drive the Gate, the output of the IC could have shorted or internal resistance and the VCC. So when you install the new MOSFET, will be fully on instead of switching at high frequency. It is a good practice to replace the MOSFET and the IC and fully check out the Gate drive resistors/diode network connected to the Gate.
Right now we cannot tell much since we do not have the pictures of the board to look at.

[Hoblah]

Re: Sony Vizo SV370XVT power supply not working.

H-man, is there any update on this issue? I am having a very similar issue and I don't really want to change a couple of MOSFETs and then have them blow again... Would you just consider ordering a new power supply board?

budm, basically you are suggesting replacing the 2 MOSFETs, 2 diodes, and the IC, correct? I will also check the resistors that connected to the Gate. Is there anyway of checking the IC to see if it has a short? Or do you just have to replace it and assume the short occurred? I am having the exact same issue as H-man, and I don't mean to hi-jack the thread, but can I load pictures of the power supply board on my TV on this thread? Or should I start a new one?

[budm]

Re: Sony Vizo SV370XVT power supply not working.

Hoblah, you can at least take the resistance reading of all the IC pins with ref to the ground pins and report the reading, also check between the Gate drive out put pins and the VCC pin, this is not 100% test that will tell you for sue if the IC is damaged or not. I myself will not take a chance of blowing up the new MOSFETs.
Good clear pictures of both side of the board will help. Check shopjimmy.com to see how much the new poaer supply is also.