PWTV8K42ASA1 Visio Power Supply Testing

[torrespedroa]

Good morning everybody: How can I test subject PS outside the tv? Thanks
This PS is for Vizio VA22LFHDTV10T

[budm]

Re: PWTV8K42ASA1 Visio Power Supply Testing

This is how;
https://www.badcaps.net/forum/showthread.php?t=39740
We have no idea what you have EXACTLY.

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

Dear friends: I'm sorry for the vague of my request. Next time will do my homework before posting.
What we have here is a dead 22" inches Vizio tv model VA22LFHDTV10T. No standby, no red led....no nothing. As you may know this is a pwr sup./inverter board. It does power both, main board as well as the LEDs.
TV started by first turning on and going off after a few minutes. Kept doing this for a couple of days....finally staying dead at all. Attached are board pics. Thanks for any help. Hope being more explicit will get to better troubleshooting.
1. No buldged caps, no overheating signs, good fuse, good transformers, diodes, resistors, thyristor.

[dskall]

Re: PWTV8K42ASA1 Visio Power Supply Testing

What voltage dc do you have across main capacitor with board plugged in? Nice to have picture of connector and pin description. What voltages on pins?

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

What voltage dc do you have across main capacitor with board plugged in? Nice to have picture of connector and pin description. What voltages on pins?

Will get voltages readings later. Here is the connector pic. Thanks for your input.

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

What voltage dc do you have across main capacitor with board plugged in? Nice to have picture of connector and pin description. What voltages on pins?

Main cap voltage is 168DC

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

Main cap voltage is 168DC

Bridge rectifier working fine.

[dick_barton]

Re: PWTV8K42ASA1 Visio Power Supply Testing

Can you also post a picture of the underneath of the board.
What voltages if any do you have on CN902

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

[QUOTE=dick_barton;746518]Can you also post a picture of the underneath of the board.
What voltages if any do you have on CN902[/QUOTE

Voltages on CN902
Ground to pin1=0
To pin 2=0
To pin 3=0
To pin 4=5VDC
To pin 5=5VDC
Pins 6-8 are ground
Ground to pin 9=12VDC
To pin 10=12VDC
To pin 11= N/C
To pin 12=0
Attached solder side pic.

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

[QUOTE=torrespedroa;746525]

Can you also post a picture of the underneath of the board.
What voltages if any do you have on CN902[/QUOTE

Voltages on CN902
Ground to pin1=0
To pin 2=0
To pin 3=0
To pin 4=5VDC
To pin 5=5VDC
Pins 6-8 are ground
Ground to pin 9=12VDC
To pin 10=12VDC
To pin 11= N/C
To pin 12=0
Attached solder side pic.

This pic. is better focused...

[budm]

Re: PWTV8K42ASA1 Visio Power Supply Testing

That is an always on power supply and that power supply section is working fine otherwise you will not the 12V and the 5V.
Based on those DCV readings of the connector to the main board, it looks like the main board is not sending any command signal to turn on the backlights inverter circuit, and no backlights dimming signal either.
Did you take pictures of the whole monitor showing all the boards?
BTW in your post 9, always put the pin names of the connector so we can easily identify each pin as to what they are.

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

Thanks for all inputs. What two wires need to be jumped to activate the power to the LEDs ? I have a homemade CFL tester to conduct this test. Thanks. Is it ok to use a 1k oh ohms resistor as a jumper? Thanks

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

That is an always on power supply and that power supply section is working fine otherwise you will not the 12V and the 5V.
Based on those DCV readings of the connector to the main board, it looks like the main board is not sending any command signal to turn on the backlights inverter circuit, and no backlights dimming signal either.
Did you take pictures of the whole monitor showing all the boards?
BTW in your post 9, always put the pin names of the connector so we can easily identify each pin as to what they are.

Does the main board have to do with the power/standby leds in from of the TV? There are No lights there. Thanks

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

[QUOTE=torrespedroa;746525]

Can you also post a picture of the underneath of the board.
What voltages if any do you have on CN902[/QUOTE

Voltages on CN902
Ground to pin1=0 Pin 1 PID
To pin 2=0. Pin 2 BL- ONN-OFF
To pin 3=0. Pin 3 Bright
To pin 4=5VDC. Pin 4 5v
To pin 5=5VDC. Pin 5 5v
Pins 6-8 are ground
Ground to pin 9=12VDC Pin 9 12v
To pin 10=12VDC. Pin 10 12v
To pin 11= N/C
To pin 12=0. Pin12 STANDBY
Attached solder side pic.

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

Still looking how to manually turn on the high voltage section feeding the screen LEDs . Thanks.

[dskall]

Re: PWTV8K42ASA1 Visio Power Supply Testing

I believe you would need to jump pin2 to pin5 to turn on backlights

[torrespedroa]

Re: PWTV8K42ASA1 Visio Power Supply Testing

I believe you would need to jump pin2 to pin5 to turn on backlights

Thanks, that's correct. Already did it by trial and error, but using logic. A positive signal has to be driven to on/off pin. Voltage reading wa 330 acv. Thanks again. This means the screen is a ctl, not LEDs. Voltage for LEDs is around 90 to 95 DCV, as seen on some other tvs I had repaired.

Conclusion: There is not any signal from the main board to turn on the high voltage stage. Will look into it this week. Thanks to all that got interest in helping me out. As a matter of fact, there was a member that suggested that the problem was at the main board ( read all posts). My special appreciation to him. (That was budm) Post #11

[budm]

Re: PWTV8K42ASA1 Visio Power Supply Testing

Remove the connector to the main board first and then use 470~1K resistor between BL_ON pin and the pin 5 (5V) and see if the backlights will come on, if not it may need another resistor (same value) between pin 3 and pin 5 (5V).