Riddled TV Repair Forum

_Bill · Guest

Anyone have any tips or SM for this Vizio VX37L. It comes on with backlight for a couple of seconds then shuts off. I disconnected the master and slave inverters and have 24v for 30-40 seconds then turns off. I have the 5v standby and 12v for the 30-40 seconds also. The 5v stays. Any help would be appreciated.

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Ming · Guest

Hi, first identify the power supply unit is working OK. Put the power supply out of TV cabinet. find out which pin is stand by 5V terminal, and which pin is for the on/off control. That is very easy, look at all pins that has big caps connect to it is output pins the stand by pin is always output 5V after just connect to wall outlet source supply. The one pin that is going to the terminal pin via a 5K or 10K resistor that is on/off pin. there should only one of this pin jump it to 5V pin then re-connect it to wall outlet. every output pin should working fine and output OK. Check it's Voltage make sure they are output the right voltage, and check all the Big Caps is it all are full capacity. no any one dry out or portion dry out. LCD TV must the power supply working good or it will not working fine.

_peggs · Guest

is the Power Supply being 'told' to turn off ???........Check Turn_On/Remote/On_Off pin on PS.....
Peggs

_bill · Guest

The On/Off pin on power supply reacts just like the 24v,12v lines. I get
backlight after 3 seconds at turn on. Then 3 seconds later the backlight
goes out. But the 24v,12, and 4.75 at On/Off pin of P.S remain another 10
seconds and then they go off. The 5v standby stays a constant 5v. Any help diagnosis would be great. Thanks!! Ming Yu and Peggs for the heads up.

_peggs · Guest

when the On-Off goes off.......the 12v and 24v are gonna go.......so the Supply is being TOLD to shutdown.
I don't think it's a supply problem.......Sounds more like an Inverter problem,although Inverter feedback may go THRU the T-con pcb.
Does the 24v Stay UP(30 seconds) when loaded(Inverter incircuit) ???
Neon Bulb or O'scope to see if each Inverter Transformer has output......if one doesn't,you're probably gonna get the exact symptom you've got.
Inverter feedback is probably need for the set to stay On.

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_bill · Guest

Yes the 24v is there when loaded. The neon bulb only indicates HV when the backlight is lit.The 24v remains after the backlight goes out. And the HV goes away. This unit has the master and slave inverters. I can't find much of anything for this Vizio. Any thoughts fellow techs??

_dennis · Guest

Resolder the little transformers on the inverter boards

_Peggs · Guest

All Inverter's Transformers have Drive(neon glow,or O'scope waveform) and All Lamps light ???(albeit momentarily)......
if even one is a no-go,the set will do just as it's doing.
or if one Transformer Drive is at a lower level,it will do just as it's doing.
Check resistance of all Iverter Transformers,Primary and Secondary......look for one 'different' than the others.

One of the VX32L's I had with broken screens,used Lamps that had a CHEAP-looking tip on each end for connection.I could EASILY IMAGINE a bad connection developing,and the set sensing it,and shutting down.......
A Different Brightness(or none) of that Lamp would probably occur......turn the lights own in your shop and look closely at the Lamp(s) brightness.
There were 16 Lamps in these VX32Ls........
(one of these VX32L's showed-up with a broken Lamp,done when they were bringing it to me.When I picked it up,out of the back of the SUV,I heard the pieces of Glass inside.)

curt wolfe · Joined: 24 Feb 2009 Posts: 51

Check/replace c112 & c113, very common.