Vizio E550i-b2e no standby voltage

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Well I checked the solder joints. Everything looked good. However I noticed when I first plug tv in I will get the standby voltage for about 5 seconds then it drops to 0 bit it is a gradual drop.

[nomoresonys]

Re: Vizio E550i-b2e no standby voltage

ok, see if that same gradual drop happens, with everything unplugged from the powerboard except the power cord of course, so you just turn on the power strip while your meter probes are in place.

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

It already is unplugged. I am just working on the smps.
Thanks

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

The vcc is stable for the first 5 seconds then goes crazy after that.

[nomoresonys]

Re: Vizio E550i-b2e no standby voltage

you checked ALL diodes in diode mode?

[nomoresonys]

Re: Vizio E550i-b2e no standby voltage

so what's going on with D901? looks very hot, I would just change it out to rule it out.

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Ya I checked all the diodes in diode mode and suspected ones I unhooked one end. All was good. Lol that is what I was trying to figure out. That is the only the only thing that lit up. I think I will just change it out and see what happens.

[dskall]

Re: Vizio E550i-b2e no standby voltage

Have you checked the secondary side? If you have 5v you can put power to your 5v output with board not plugged in. Check for shorts and also check feedback circuit.

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Ya I am going to try that when I get home. I will let you know my findings.

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Well my Bench power supply didn't get delivered. However when I got home I was messing with it and my standby would stay on for a couple minutes. Then if I unplugged it and waited a few minutes and plugged back in it would come back.

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Well I finally got the standby back. It was cold solder joints on that diode. However I moved on to the pfc circuit. It's not working. I have my vcc voltage and 2.9v on drive pin of ic going to gate of mosfet but I lose my voltage at a resistor any ideas.

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Here is the datasheet.

[dskall]

Re: Vizio E550i-b2e no standby voltage

You seem to be giving us bits and pieces of information. So now you also have a pfc problem. What are your main cap. voltages in standby and powered on?

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

In standby mode it's 167vdc. Powered on its 167vdc also. Originally I didn't have standby voltage, but now I have that so on to the next problem. Sorry for the confusion.

[R_J]

Re: Vizio E550i-b2e no standby voltage

Well I finally got the standby back. It was cold solder joints on that diode. However I moved on to the pfc circuit. It's not working. I have my vcc voltage and 2.9v on drive pin of ic going to gate of mosfet but I lose my voltage at a resistor any ideas.

So your pin8 Vcc voltage is 12 volts?

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

I have 15.6v on vcc

[R_J]

Re: Vizio E550i-b2e no standby voltage

You said you replaced Q800 and R804a, was Q800 shorted and R804a open?

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Yes

[Mbd3]

Re: Vizio E550i-b2e no standby voltage

Here is what voltages I have on that ic
Pin#
1. 1.074v
2. 5.837v
3. 0.423v
4. 0v
5. 0v
6. 0v
7. 2.418v
8. 15.3v

[R_J]

Re: Vizio E550i-b2e no standby voltage

Yes

Then the ic is damaged. When the mosfet shorted and the source resistor opened, 165v was applied through R805 to the CS pin of the ic, damaging it.