Vizio E390VL 5 volt standby only

[piddler]

Gave up on my last project and decided to take on this Vizio. This TV shows no signs of life other than having my 5 volt STBY. The Vizio logo doesn't even illuminate when plugged in. No backlight. No display even when shining a flashlight to the LCD. No 12 volt is present to or from power supply and main board. To try and eliminate power supply as the cause, I used Budm's suggestion and used a couple of 3.3k resistors to jump 5 volt to Remote/On Off and backlight on. Power supply turned on I assume because I now have 12 volts to or from main board. Backlights came on as well. So im thinking main board is the problem. Some things I've tested:

1. Fuse FP1 on main board test good and reads 5 volts without jumper
2. Fuse FP2 test good but has 0 voltage on both sides without jumper.
3. 400 volt cap on power supply:

170 volts just plugged in (not forcing power supply on)
307 volts with PS forced on. Shouldn't it be at least 380 or so?

If I disconnect everything from the power supply except AC in of course and force the PS on, the main filter cap goes crazy. Ranging up and down from as low as 220v and highest only reaching 307v. With all boards connected, It stays at a steady 307v. Thanks in advance for anyone willing to help me out on this.
Attached Thumbnails

[budm]

Re: Vizio E390VL 5 volt standby only

Check the capacitance of the main filter cap?
You do have Pfc Voltage problem if it is that low BUT if the main board is good then you should get the Pson to turn on the power supply even if the Pfc Voltage is low.

[piddler]

Re: Vizio E390VL 5 volt standby only

I don't have an ESR meter Budm. I have a decent DMM. I think the most I can do is check resistance of that cap. If I put it in the 400 ohm range, it never moves from OL. That's in circuit though. Thanks for your quick response. Im willing to try any suggestions you have. Im far from a professional, but I just enjoy working on electronics and learning as I go.

[martyparish]

Re: Vizio E390VL 5 volt standby only

Budm was suggesting to test the capacitance not the esr. Many meters have a capacitance setting but not all.

[piddler]

Re: Vizio E390VL 5 volt standby only

My meter doesn't test capacitance Martyparish. Sorry. I'm confused on why my voltage fluctuates when I disconnected everything from the PSB. I tested all the pins at CN201 yesterday and they're also erratic with the main board disconnected. From -0.34 to +0.52. Even on the ground pins. Hope I don't sound dumb. I was thinking I should still get the steady 5v STBY. Only way I do is if the main board is connected.

[piddler]

Re: Vizio E390VL 5 volt standby only

Here's the legend.

[budm]

Re: Vizio E390VL 5 volt standby only

'I tested all the pins at CN201 yesterday and they're also erratic with the main board disconnected. From -0.34 to +0.52. Even on the ground pins.'

What do you mean by 'Even on the ground pins.'?

[piddler]

Re: Vizio E390VL 5 volt standby only

I mean the ground pins are showing the - to + voltage fluctuation also, same as all the other pins. Sorry Budm. I could have worded that a little better. I know the ground should be 0. PSB just goes crazy when the main board isn't connected.

[budm]

Re: Vizio E390VL 5 volt standby only

If you put both meter probes on the GND pin and the meter shows fluctuation then the meter is not working right, if I understand what you are saying.

[piddler]

Re: Vizio E390VL 5 volt standby only

I had ground probe to chassis. No matter what pin I probe, it's reads the fluctuating voltage. If I connect main board to PSB, my meter reads a steady 5.2v on pins 1-3. 0 volts on the other 11 pins. I will double check my meter battery this afternoon though Budm. I always try to find your name in the threads I read through because of the knowledge and time you spend trying to help like myself. Thanks.

[budm]

Re: Vizio E390VL 5 volt standby only

OK, I will wait for you to verify that the meter and the batteries are OK, mean while I will look at the board layout.

http://www.shopjimmy.com/catalogsear...q=Vizio+E390VL

Vizio 0500-0405-1371 (FSP158-2PS01A) Power Supply Unit.
http://www.shopjimmy.com/vizio-0500-...upply-unit.htm

Pictures provided by shopjimmy.

[piddler]

Re: Vizio E390VL 5 volt standby only

Thanks Budm. Sure would be nice if Vizio had a service manual online huh?

[budm]

Re: Vizio E390VL 5 volt standby only

I saw some of the so called 'VIZIO service manuals' but they do not have any diagram what so ever.
For example:

[piddler]

Re: Vizio E390VL 5 volt standby only

Ok Budm. DMM seems to be fine. Put a new 9 volt in just to be sure. Measured my ac outlet 126 vac. 9 volt battery measured 8.7v. Measured voltage at CN201 again. Same crazy fluctuating voltage. Makes no sense to me.

[piddler]

Re: Vizio E390VL 5 volt standby only

I started testing diodes today and would like to get some input on one I'm suspicious of. I tested in diode mode with the diode removed from the power supply board. I've attached a photo of where it was on the board. Location is D660 and it measures .297. Diode markings read SR506 below that is CI4. Is this a good working diode? Or part of my problem?