Westinghouse VR-3710 stuck in standby

[dick_barton]

Re: Westinghouse VR-3710 stuck in standby

The electrolytic capacitor(s) that the diode connects to may need changing but I would replace the diode first and check the 24V supply is solid.

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

Cool. Order placed.

The existing diode has two of what I assume are rf chokes. Should I reinstall those on the new diode?

[dskall]

Re: Westinghouse VR-3710 stuck in standby

Maybe you need to post picture of this diode. If you tested out of circuit there should be no capacitive effect in reading, nor rf chokes.

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

You can see them in the original photos I posted. They're anchored with green adhesive. One on each lead next to the diode body.

[dskall]

Re: Westinghouse VR-3710 stuck in standby

OK yes you need to put them on new diode.

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

I can find nothing about those rings in my research. If anyone has a link to an explanation, please post it.

[vinceroger69]

Re: Westinghouse VR-3710 stuck in standby

thats a ferrite bead on the leg of the diode there are some refrence to them in google searches im sure budm if he sees this thread will know and explaine for us its purpose.

[budm]

Re: Westinghouse VR-3710 stuck in standby

The Ferrite bead is put on the leg of the device to form a very small inductor.

[budm]

Re: Westinghouse VR-3710 stuck in standby

[vinceroger69]

Re: Westinghouse VR-3710 stuck in standby

Thanks budm ive saw them before mosfets etc but not on a diode before some good reading in your links thanks.

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

Thanks! From that document:

A major noise source has been traced to the oscillation from the MOSFET at switching on-off transient. Typically, parasitic oscillation frequencies are in the range of several tens to hundreds of megahertz. The parasitic oscillation can cause gate-source breakdown, bad EMI, large switching losses, losing gate control, and can even lead to MOSFET failures. A ferrite bead is often used on MOSFET gate leads to provide stable operation by suppressing parasitic oscillation, while minimizing switching losses. In fact, adding a ferrite bead is more effective than using gate resistance alone because the impedance of the ferrite bead varies by frequency.

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

Ok, replacing the diode brought back the 24v pins. The power light goes from red to green when I hit the power button, but no picture. I used a light but couldn't see anything.

The C31 cap reads 167 on standby and 383 power on.

What's my next move? Thank you.

[dskall]

Re: Westinghouse VR-3710 stuck in standby

Do you have backlights?

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

Nope.

[dskall]

Re: Westinghouse VR-3710 stuck in standby

So you need to find out if you get a backlight on voltage. It may be the one on con2f that says sw.

[dick_barton]

Re: Westinghouse VR-3710 stuck in standby

Do you have a photo of the mainboard connection to inverter

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

Still investigating.

[isherwood]

Re: Westinghouse VR-3710 stuck in standby

No voltage at any of the CON2F pins.

[dskall]

Re: Westinghouse VR-3710 stuck in standby

You have two connectors that go into the panel for backlights. You can check voltage on each as you power on the set and see if you get momentary voltage and report max voltage if any.

[dick_barton]

Re: Westinghouse VR-3710 stuck in standby

No voltage at any of the CON2F pins.

I think one of those pins, namely SW would be "Inverter On" and the voltage is missing.