Vizio VO320E 32" No display

[el3ctroded]

I have tested this panel and the power supply outputs 5V and 12V, but the inv_on line stays low.

I tested the main board and found 8 linear regulators and 1 of them (TU52) has no power. It gets power from:
At the largest white connector on the left of the image power comes in and goes through F2 then through U21 then through L57 then through TF1 to TU51 which appears to be a switching regulator which supplies TU52.

Fuses TF1 and F2 are good. Power does NOT make it to L57. Not sure why, but U21 is where power stops.

The power supply board appears to be good, just I think it's not getting the signal to turn on the inverter from the main board.

[PlainBill]

Re: Vizio VO320E 32" No display

I have tested this panel and the power supply outputs 5V and 12V, but the inv_on line stays low.

I tested the main board and found 8 linear regulators and 1 of them (TU52) has no power. It gets power from:
At the largest white connector on the left of the image power comes in and goes through F2 then through U21 then through L57 then through TF1 to TU51 which appears to be a switching regulator which supplies TU52.

Fuses TF1 and F2 are good. Power does NOT make it to L57. Not sure why, but U21 is where power stops.

The power supply board appears to be good, just I think it's not getting the signal to turn on the inverter from the main board.

In general there are three reasons power does not make it through a regulator.

1. The load is excessive.

2. The regulator is switched off (applicable only for those regulators with an On / Off control).

3. The regulator is defective.

Without the part number of U21, it's hard to say more.

PlainBill

[el3ctroded]

Re: Vizio VO320E 32" No display

I would have posted the PNs sooner but ran out of time...

U21 is 4953GM P-ch fet, likely used to switch for the power on and off
TUS1 is TPS65161 is a bias power supply
TUS2 is 17-18L

[el3ctroded]

Re: Vizio VO320E 32" No display

I measured the gates of U21, and it's at 12V so the fet is off. Wonder why. Note that there are 2 fets in U21 and they are being run in parallel.

[el3ctroded]

Re: Vizio VO320E 32" No display

Maybe I'm wrong about the PSU being fine... The smaller PSU connector (6 wires ) has low on all of them. They all appear to be control/status lines for the inverter.

[el3ctroded]

Re: Vizio VO320E 32" No display

The pwm controller for the backlight says OZ9966GN and I can't find a datasheet for it...

[el3ctroded]

Re: Vizio VO320E 32" No display

It's made by O2Micro and they don't seem to post datasheets for public viewing. I submitted a request to get it on their website, hopefully they send it.

[el3ctroded]

Re: Vizio VO320E 32" No display

I've tested the ESR of all caps on the main board, replaced 2 which had ESRs of about 2ohms on the main board. All other caps test Ok.

Tested ESR of all caps on power supply. Found 1 with ESR of about 2 ohms. Then tested capacitance of all the small electrolytics, found a 22uF that read 9uF, so just replaced all the small electrolytics.

Tested all diodes on both boards, all seem Ok. Tested all power transistors on powersupply, all seem Ok.

No change. Still no power through U21 on main board even at powerup, and no voltage on any of these pins on the power supply, even at initial powerup:
DIM, INV_ON, VBR_A, STATUS.

What do I look at? The Main board, or the power supply? I'd attempt to force the powersupply to turn on the backlight, but since I can't get the datasheet for the PWM chip, I'm not sure how to safely do so.

[el3ctroded]

Re: Vizio VO320E 32" No display

So I traced DIM, INV_ON, VBR_A, STATUS on the main board and powersupply.

Main Board:
DIM goes to TL2417 pin 21.
INV_ON goes through ~500ohm resistor to MT5380 Pin 76
VBR_A goes to a small ceramic cap and I loose it.
STATUS goes through a 10k resistor to MT5380 Pin 206

On the power supply:
They all go back to the inverter PWM chip.

[Shane711]

Re: Vizio VO320E 32" No display

I got this same problem but I can't figure it out yet. TV turns on, logo turns white but will not turn off. No backlight. All voltages on PS are good. No voltage going to Regulator TUS2. Got a very bad headache today.

U2 in 5.11 out 3.29 adj 2.04
U4 in 5.14 out 3.29 adj 2.05
U5 in 5.11 out 2.63 adj 1.38
U7 in 5.11 out 3.31 adj 2.06
U8 in 3.29 out 2.48 adj 0.00
U9 in 5.11 out 2.51 adj 1.264
U11 in 12.27 out 5.02

[dick_barton]

Re: Vizio VO320E 32" No display

What devices are U2, U4 etc ?

[vinceroger69]

Re: Vizio VO320E 32" No display

maybe a eeprom issue seems quite common on vizios if all voltages etc test ok maybe a eeprom swop next.
https://www.youtube.com/watch?v=0TJQ9-fRs0M

[Shane711]

Re: Vizio VO320E 32" No display

They are all voltage regulators. U2, U4 etc. I am thinking it is not the EEPROM, doesn't fit the normal symptoms. And because there is no voltage going to the regulator at TUS2 makes me think something else is wrong. Though if I replace the EEPROM that will either confirm or rule it out.

[Shane711]

Re: Vizio VO320E 32" No display

I got the EEPROM for this TV offline. I have not put it in the TV yet but I figured I could share the file. Now you must know you can only use this EEPROM file if you have a new Blank EEPROM IC and a way to write it to the IC. The best programmer I found so far is a SP8-A. there are better ones but the prices are over $100.

So here is the file, I had to zip so I could upload it here.
Vizio VO320E 3632-0842-0150 U18 (MX25L6406E)
MX25L6406E is the NEW IC you will need or an equivalent.
And you must have board number 3632-0842-0150 for this to work.

Enjoy

[vinceroger69]

Re: Vizio VO320E 32" No display

Thanks for sharing and i hope this fixes your set as you say it will either confirm its at fault or rule it out.