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Old 09-14-2018, 07:44 AM   #1
Rainy
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Default Standard Vizio Power Supply DPS-167DP

Hello. I just want some thoughts on a power supply I'm repairing.
I searched the forum and didn't find much on this power supply.



The IC failed. It looked like it exploded kind of. I got 5 off eBay and replaced it (with that terrible rosin solder..)

The IC gets like 9 volts on every pin except for the two separate drain pins that fluctuate between like 10 and 12 volts every half second or so.

The secondary side has no standby voltage (5vSB) and the diode is short and I haven't replaced it yet. Any thoughts on what else I should test? I didn't notice any shorts on any mosfets.

For reference for anyone with future repairs: https://www.datasheets360.com/pdf/732173695424627367
The IC is: LD7913JGM6
The TV is: M492i-B2
Manufacturer: Vizio

(also search does not work on this site? odd)

Last edited by Rainy; 09-14-2018 at 07:52 AM..
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Old 09-14-2018, 10:17 AM   #2
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Default Re: Standard Vizio Power Supply DPS-167DP

Lets start with what did you use for GND ref for your meter when you get those Voltage readings?
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Old 09-14-2018, 10:46 AM   #3
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Default Re: Standard Vizio Power Supply DPS-167DP

Quote:
Originally Posted by budm View Post
Lets start with what did you use for GND ref for your meter when you get those Voltage readings?
I used the top-right screw ground. Bottom-right in the photo.
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Old 09-14-2018, 10:48 AM   #4
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Default Re: Standard Vizio Power Supply DPS-167DP

OK, you use wrong GND ref. that is why your readings are all wrong, you are working on the hot side of the circuit so you have to use the negative leg of the main filter cap for the circuit GND ref for the hot side.
Did you also check the resistors R907A, 907B connected to the S pin of the IC and the hot side circuit GND to make sure they are still OK?
You also need to check the fusible resistor R915 to make sure it is also OK.

Last edited by budm; 09-14-2018 at 10:59 AM..
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Old 09-14-2018, 10:55 AM   #5
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Default Re: Standard Vizio Power Supply DPS-167DP

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Originally Posted by budm View Post
OK, you use wrong GND ref. that is why your readings are all wrong, you are working on the hot side of the circuit so you have to use the negative leg of the main filter cap for the circuit GND ref for the hot side.
Did you also check the resistor connected to the S pin of the IC and the hot side circuit GND to make sure it is still OK?
That just blew my mind.

Sorry, I really don't know what the main filter cap looks like.


I'm not sure what pin is the S pin. And, I'm not sure what resistor
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Old 09-14-2018, 11:03 AM   #6
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Default Re: Standard Vizio Power Supply DPS-167DP

See my updated post #4.
Main filter cap is C800A.
Look at the spec sheet of the IC, it shows which pin is the S pin.
You are working in the hot deadly side of the circuit so you need to at least plug the TV into the GFCI (Ground Fault Circuit Interrupter) and do not touch anything on the board with yours hands or body.
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Old 09-14-2018, 11:28 AM   #7
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Default Re: Standard Vizio Power Supply DPS-167DP

Quote:
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See my updated post #4.
Main filter cap is C800A.
Look at the spec sheet of the IC, it shows which pin is the S pin.
You are working in the hot deadly side of the circuit so you need to at least plug the TV into the GFCI (Ground Fault Circuit Interrupter) and do not touch anything on the board with yours hands or body.
Funny, because that breaker doesn't trip in our place at all.
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Old 09-14-2018, 01:06 PM   #8
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Default Re: Standard Vizio Power Supply DPS-167DP

I am not talking the circuit breaker, I am talking about using GFCI outltet such as one used in the bathroom.
You know what GFCI outlet is, right? It is for your own safety unless you do not care.
https://home.howstuffworks.com/question117.htm

Last edited by budm; 09-14-2018 at 01:07 PM..
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Old 09-16-2018, 02:04 PM   #9
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Default Re: Standard Vizio Power Supply DPS-167DP

Quote:
Originally Posted by budm View Post
I am not talking the circuit breaker, I am talking about using GFCI outltet such as one used in the bathroom.
You know what GFCI outlet is, right? It is for your own safety unless you do not care.
https://home.howstuffworks.com/question117.htm
I went and measured that same chip again. I get ~50v now on all of the pins except the drain to the mains filter cap (I guess those are on the front visible side)

I also get ~50v measuring to the 5VSB from the mains filter caps.

This is a new voltmeter, it read 5v last time I checked.

Can anyone else chime in with some advice?

I know that diode is bad, but it has no power to it at all.

Last edited by Rainy; 09-16-2018 at 02:05 PM..
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Old 09-16-2018, 02:47 PM   #10
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Default Re: Standard Vizio Power Supply DPS-167DP

there is a reason for that white checkerboard marking on the board, it tells you what components are on the HOT side and which are on the COLD side. ALL voltages on the HOT side are measured with reference to the HOT GROUND (Main Filter or bridge rectifier (-)).
All voltages on the COLD side are measured to Chassis ground (like 5 volt standby)

What do you mean by THAT DIODE???? they have board locations.

Last edited by R_J; 09-16-2018 at 02:49 PM..
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Old 09-16-2018, 04:07 PM   #11
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Default Re: Standard Vizio Power Supply DPS-167DP

Update: I just soldered on a new diode from a VCR that was "40" instead of "30" and works great.

Thanks for pointing me in the right direction. I realized the TV was tripping after I measured power from the mains cap on both sides in voltage mode and hitting the power button. The Meter would go out of range about 10 times, then TV would be in standby mode.
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Old 09-16-2018, 04:09 PM   #12
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Default Re: Standard Vizio Power Supply DPS-167DP

Quote:
Originally Posted by R_J View Post
there is a reason for that white checkerboard marking on the board, it tells you what components are on the HOT side and which are on the COLD side. ALL voltages on the HOT side are measured with reference to the HOT GROUND (Main Filter or bridge rectifier (-)).
All voltages on the COLD side are measured to Chassis ground (like 5 volt standby)

What do you mean by THAT DIODE???? they have board locations.
The one marked in red on the photo. Sorry man, it was kind of hard to see. it's working anyway

I recorded the repair on camera of the diode addition:
https://youtu.be/5MKF0J0qMVM

Last edited by Rainy; 09-16-2018 at 04:17 PM.. Reason: https://youtu.be/5MKF0J0qMVM
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