Vizio VF552XVT Power Problem.

[wadehavens]

Hi there.

I'm having a problem with my TV turning off. It's shutting down when the LED driver board starts up. I've taken the power supply out in the hopes of finding some swollen caps, but all of them look fine.

So I put the power supply back in and found that if I only plug in one of the LED driver board power plugs, the TV turns on and works. If I plug them both in the power supply turns off. So basically the problem seems to be on the 24V rail. All the voltages are present without the LED driver board plugged in. 5v,12v,18v, and 24v.

My question is, what does the "slave" plug on the LED driver board do if the TV still works without it? , and do you think that replacing the caps on the 24v rail will do the trick?

Thanks!!

-Wade

[R_J]

Re: Vizio VF552XVT Power Problem.

Can you hold the tv in front of your monitor so we can see the boards or provide some pictures.
How many driver boards are used? Are there 2 driver boards One Master and one Slave?
There are2 other threads on this model that might help, use the search and use your model number to locate them

[CapLeaker]

Re: Vizio VF552XVT Power Problem.

could be a bad led in the other string too...

[wadehavens]

Re: Vizio VF552XVT Power Problem.

Can you hold the tv in front of your monitor so we can see the boards or provide some pictures.
How many driver boards are used? Are there 2 driver boards One Master and one Slave?
There are2 other threads on this model that might help, use the search and use your model number to locate them

There is only one driver board.

Here a couple of pics.. Sorry if they suck my phone is a piece of garbage.

[budm]

Re: Vizio VF552XVT Power Problem.

Can we at least see GOOD CLEAR FOCUSED pictures of the whole backside of the TV showing how all the boards are connected together? borrow better phone?
We do not have the TV or the boards in front of us to look at, so it is not easy to do long distant troubleshooting, pictures are all we have to go by.

[R_J]

Re: Vizio VF552XVT Power Problem.

So which is the plug you disconnect that causes the tv to stay on? I don't see "slave" marked on any of them. CN?

[wadehavens]

Re: Vizio VF552XVT Power Problem.

So which is the plug you disconnect that causes the tv to stay on? I don't see "slave" marked on any of them. CN?

Cn2 is the plug I can have disconnect.

[R_J]

Re: Vizio VF552XVT Power Problem.

When Cn2 is connected does it kill the 24 volts? You should be able to check the voltage at the fuse F201 on the drive board. If the voltage is low or missing.
Check Q211,Q212,Q204,Q205 and D202,D203, D207,D208, One or more components might be shorted.

[wadehavens]

Re: Vizio VF552XVT Power Problem.

Just a quick side note. The power supply will stay on with either cn1 or Cn2 connected, but not with both.

[wadehavens]

Re: Vizio VF552XVT Power Problem.

Here is a Pic of the back of the tv

[wadehavens]

Re: Vizio VF552XVT Power Problem.

When Cn2 is connected does it kill the 24 volts? You should be able to check the voltage at the fuse F201 on the drive board. If the voltage is low or missing.
Check Q211,Q212,Q204,Q205 and D202,D203, D207,D208, One or more components might be shorted.

Everything tests good. The entire power supply shuts off when both CN1 and CN2 is connected. If I unplug either one of them, the power supply works as normal. Of course, the back light does not come on when only CN2 is connected but does when only CN1 is connected.

[R_J]

Re: Vizio VF552XVT Power Problem.

If you disconnect CN3 & CN4 going to the panel led's will the power supply stay on with CN1 & CN2 connected? (you will not get any backlight)

CN2 only has +24 volts, CN1 has +24 volts plus the control signals

[wadehavens]

Re: Vizio VF552XVT Power Problem.

If you disconnect CN3 & CN4 going to the panel led's will the power supply stay on with CN1 & CN2 connected? (you will not get any backlight)

CN2 only has +24 volts, CN1 has +24 volts plus the control signals

I unplugged CN3 and CN4 and the power supply works as it should. I then reconnected CN3 and half of the backlight works. Same result with CN4 only. Then reconnected both and the supply shuts off.

[R_J]

Re: Vizio VF552XVT Power Problem.

It could be that the power supply can't supply enough current
If you just connect one set of led's can you go into the menu and see what the backlight level is set at? and turn it down if you can and see if it makes a difference.
It could be one of the small caps (IE 4.7 - 22 @ 50v) that are bad in the power supply.
The won't look bad.

[wadehavens]

Re: Vizio VF552XVT Power Problem.

It could be that the power supply can't supply enough current
If you just connect one set of led's can you go into the menu and see what the backlight level is set at? and turn it down if you can and see if it makes a difference.
It could be one of the small caps (IE 4.7 - 22 @ 50v) that are bad in the power supply.
The won't look bad.

I replaced the smaller caps. One was a 2.2 @ 50v and the other a 100 @ 50v. Neither made a difference. It still shuts down if both sides of the backlight is connected. The backlight brightness doesn't change a thing. It's for sure a problem with the 24v side, at least is seems that way, but other than replacing the big caps I'm not sure what else to do. Possibly the transistors on the 24v rail maybe?

If I leave it off for a day or so, it will turn on for about 40 minutes.

[budm]

Re: Vizio VF552XVT Power Problem.

So only 24V power supply shutdown but the all other power supplies still on?
I also want you to try this: get the backlights to come on then go to the on screen adjustment and then turn down the backlights level (not Brightness) as low as possible on all inputs, then turn off the TV and connect all the cables back in the LED driver board and see if the backlights will come on and stay on.

[wadehavens]

Re: Vizio VF552XVT Power Problem.

So only 24V power supply shutdown but the all other power supplies still on?

No...the 5v stays on but the rest of the power supply shuts down. But it seems to be triggered by the 24v rail since disconnecting half of the backlight will allow the supply to start up. So I suppose it could be anywhere in the power supply other than the 5v rail.

[budm]

Re: Vizio VF552XVT Power Problem.

The 24V has its own power transformer T1 for making the 24V.
The 12V and 18V are generated by another transformer T2.
The standby power supply is generated by transformer T901.
So something is not right that the 12V/18V section gets shutdown too.
You may want to monitor the PS-ON pin to see if it drops out when shutdown happens.
The power supply also PFC Voltage booster circuit that you should also check the DCV right between the two legs of the main filter cap to see what happens to that boosted Voltage.
This is your power supply, right?
http://www.shopjimmy.com/vizio-0500-...pply-unit.htm#
Vizio 0500-0507-0670 (DPS-450RP A) Power Supply for VF552XVT

[wadehavens]

Re: Vizio VF552XVT Power Problem.

The 24V has its own power transformer T1 for making the 24V.
The 12V and 18V are generated by another transformer T2.
The standby power supply is generated by transformer T901.
So something is not right that the 12V/18V section gets shutdown too.
You may want to monitor the PS-ON pin to see if it drops out when shutdown happens.
The power supply also PFC Voltage booster circuit that you should also check the DCV right between the two legs of the main filter cap to see what happens to that boosted Voltage.
This is your power supply, right?
http://www.shopjimmy.com/vizio-0500-...pply-unit.htm#
Vizio 0500-0507-0670 (DPS-450RP A) Power Supply for VF552XVT

Yes, thats the power supply.

[wadehavens]

Re: Vizio VF552XVT Power Problem.

The 24V has its own power transformer T1 for making the 24V.
The 12V and 18V are generated by another transformer T2.
The standby power supply is generated by transformer T901.
So something is not right that the 12V/18V section gets shutdown too.
You may want to monitor the PS-ON pin to see if it drops out when shutdown happens.
The power supply also PFC Voltage booster circuit that you should also check the DCV right between the two legs of the main filter cap to see what happens to that boosted Voltage.
This is your power supply, right?
http://www.shopjimmy.com/vizio-0500-...pply-unit.htm#
Vizio 0500-0507-0670 (DPS-450RP A) Power Supply for VF552XVT

The PS-ON voltage stays on when the power supply shuts off. About 3.3 volts.

I'm not sure where to test the voltage on the main filter cap since the cap is under the large heatsink. I've been testing the power supply mounted to the TV.