Vizio E472VL No 5v Standby

[chuckup]

Hello All,

Have a Vizio E472VL that when I first received appeared dead. Gained access to the boards and verified fuses on the power board. Both T4A and T5A are good. Continuity good and voltage on both sides

Checked voltages on the cold side output connector to the main board. The readings are with the connector to the main board removed.

Pin 1 Dim - 0V
Pin 2 Status - 0V
Pin 3 On/Off - 0V
Pin 4 Standby - 0V
Pin 5 +12 - 0V
Pin 6 +12 - 0V
Pin 7 +12 - 0V
Pin 8 9 10 & 11 Gnd
Pin 12 +5 - Not Steady 5.1 to 5.2V
Pin 13 +5 - Not Steady 5.1 to 5.2V
Pin 14 +5 - Not Steady 5.1 to 5.2V

I checked the voltage across the Bridge Rectifier. I have 174 between the + and -

Next I checked voltages at the SMPS U101. This is a Q0465RS. The readings were as follows

Pin 1 Drain - 174V
Pin 2 Gnd - 0V
Pin 3 VCC - Fluctuating between 9 and 11V
Pin 4 Feedback - Fluctuating between 0 and .2V
Pin 5 Sync - Fluctuating between 0 ans .4V
Pin 6 Startup - Fluctuating between 87 and 160V

I checked the C105 tied to the VCC pin out of circuit. Its good. Have not removed any smd devices yet just been checking them in circuit. Checked all low ohm resistors and high voltage caps around this SMPS. Tested Opto-couplers.

I verified the two rectifier diodes D201 and D202 and Q201 on the cold side output out of circuit with DMM

I verified the four mosfets Q706 - Q709 out of circuit with DMM.

Not well versed on component level troubleshooting and am seeking a little bit of guidance on what to check next. Thinking this might be something easy I am overlooking.

Thanks,

[budm]

Re: Vizio E472VL No 5v Standby

"The readings are with the connector to the main board removed."
We need the Voltage readings with all the connections back in place when TV is in standby and when the power switch is activated.

[chuckup]

Re: Vizio E472VL Dead Set / No Standby Voltage

Hello budm,

The television is working fine now. I will fill you in on what happened. I know now its important to give the complete history when posting!

When I first received the TV it appeared dead. No orange Vizio logo on the front of the TV. Opened the rear and checked the fuses first. Then measured the voltages at the connector going to the mainboard with all boards still connected.

Pin 1 Dim - 0V
Pin 2 Status - 0V
Pin 3 On/Off - 0V
Pin 4 Standby - 0V
Pin 5 +12 - 0V
Pin 6 +12 - 0V
Pin 7 +12 - 0V
Pin 8 GND - 0V
Pin 9 GND - 0V
Pin 10 GND - 0V
Pin 11 GND - 0V
Pin 12 +5 - 1.2V
Pin 13 +5 - 1.2V
Pin 14 +5 - 1.2V

All boards disconnected

Pin 1 Dim - 0V
Pin 2 Status - 0V
Pin 3 On/Off - 0V
Pin 4 Standby - 0V
Pin 5 +12 - 0V
Pin 6 +12 - 0V
Pin 7 +12 - 0V
Pin 8 GND - 0V
Pin 9 GND - 0V
Pin 10 GND - 0V
Pin 11 GND - 0V
Pin 12 +5 - .4V
Pin 13 +5 - .4V
Pin 14 +5 - .4V

At this point I knew I had a power supply issue and removed the board to play with while at work. Powered up on bench and still same voltages as above.

Started checking voltages up to the SMPS (Q0465RS). At this device I was seeing

Pin 1 Drain - 174V
Pin 2 GND - 0V
Pin 3 VCC - .6V
Pin 4 FB - 0V
Pin 5 Sync - 0V
Pin 6 Startup 87V

All were steady but not correct. Started pulling devices around the SMPS area to test out of circuit. All pulled tested good. Tested all fets and diodes out of circuit. Tested all secondary side filter caps. Re-soldered the leads on the switch mode transformer.

After all of the above de-soldering and soldering the above components I tested operation to verify where I was at. The symptom changed to my original post which now I know was a normal working power supply without any load applied to the output.

Installed when I got home from work and has been working fine for two days now so obviously a cold solder joint. Only problem is I do not know which solder joint was bad. I will do a better job next time testing operation between component removal and replacement.

Here are my voltages for working TV

Standby

Pin 1 Dim - 3.3V
Pin 2 Status - .5V
Pin 3 On/Off - 55mv
Pin 4 Standby - 3.2V
Pin 5 +12 - 12.3V
Pin 6 +12 - 12.3V
Pin 7 +12 - 12.3V
Pin 8 GND - 0V
Pin 9 GND - 0V
Pin 10 GND - 0V
Pin 11 GND - 0V
Pin 12 +5 - 5.2V
Pin 13 +5 - 5.2V
Pin 14 +5 - 5.2V

TV on

Pin 1 Dim - 3.3V
Pin 2 Status - 20mv
Pin 3 On/Off - 2.9
Pin 4 Standby - 3.2V
Pin 5 +12 - 12.3V
Pin 6 +12 - 12.3V
Pin 7 +12 - 12.3V
Pin 8 GND - 0V
Pin 9 GND - 0V
Pin 10 GND - 0V
Pin 11 GND - 0V
Pin 12 +5 - 5.2V
Pin 13 +5 - 5.2V
Pin 14 +5 - 5.2V

Edited title since Standby Voltage was not 5V

[kgavionics]

Re: Vizio E472VL No 5v Standby

i'm glad that it was an easy fix for you.