westinghouse vr3215

[lookimback]

Re: westinghouse vr3215

OK the part number is OB3328UQP, not 0(zero)B3328UQP.

[lookimback]

Re: westinghouse vr3215

OK, sorry I took so long. The numbers on the SMD PWM are line one B13022, line two 0B3328UQP. Resistance readings on the MOSFETs are 10.01k, 41.9k, 39.1k, 9.99k. No way to check the caps right now. I'm going to look for an ESR meter on eBay right now.

[lookimback]

Re: westinghouse vr3215

I'll post them when I get home tonight.

[budm]

Re: westinghouse vr3215

OK, it is just a simple full bridge drive circuit driving the Inverter xformers primary side in parallel, since all the lamps are not getting full drive voltage, it has to be a fault in the common circuit some where. Can you get the P/N of that SMD PWM IC?
This is the simplified diagram, you should take the resistance reading between the Source and Drain pins of the 4 MOSFETs. C209, 210 should be check for resistance leakage and value (I do not know what the value is).

[lookimback]

Re: westinghouse vr3215

OK. Its a 35v 470uf. I'll replace it with a Panasonic FC. I think I'll order about a dozen since that cap is beginning to look like a very common cap on inverter boards. Thank you for the help. I'll let you know how it turns out.

[budm]

Re: westinghouse vr3215

"I don't have a green cap but I think you are talking about the blue electrolytic that is right in the center of the top side of the board. Am I correct?" Yes (it looks green to me, but my eyes are not that good anymore).

[lookimback]

Re: westinghouse vr3215

Oh, I wish I would have known that sooner. Well, I can still use the Fluke for most other testing purposes. Can you recommend a good mid priced ESR meter please? Thank you.

[tom66]

Re: westinghouse vr3215

You can't use a capacitance meter to check most capacitors, as capacitors usually maintain their capacitance when they fail. It's their ESR that goes up.

[lookimback]

Re: westinghouse vr3215

I ordered a Fluke 115 multimeter from eBay yesterday. Right now I don't have a way to test it. I bought a $20 ESR meter from amazon but it doesn't work. The Fluke works with up to 9999 uf caps. That should be good for TV repair. I don't have a green cap but I think you are talking about the blue electrolytic that is right in the center of the top side of the board. Am I correct?

[budm]

Re: westinghouse vr3215

Not sure if you have ESR meter to test that green electrolytic cap laying side way, I would replace that cap.

[lookimback]

Re: westinghouse vr3215

OK. The help is certainly appreciated. This one really had me stumped. Thanks.

[budm]

Re: westinghouse vr3215

Thanks, I also found good pictures at SJ.
http://www.shopjimmy.com/catalogsear...nghouse+vr3215

So far it looks like the lamps are not getting the full voltage to drive the lamps completely. I will have to study the board to see how it works.

[lookimback]

Re: westinghouse vr3215

Yes, I have the 24vdc. Here's the pics. I took close ups of the back of the board so there are 5 pics. 1 front, 1 back, and then top third, middle third and bottom third of the back. This TV is the first one that was a real challenge. I've learned more from this one than all the others combined.

[budm]

Re: westinghouse vr3215

"BK voltage is 2.9v and DM is 1.2v."
BK is more likely to be Backlights ON signal from the main board.
DM is the Backlights Dimming control voltage from the main board, 5V = Max lamps brightness, 0V = dimmed.
So it looks like the Main board is sending out the correct signals to the Inverter board, but the Inverter board will need 24Vdc from the power supply board to run. So do you have 24VDC? Pictures of the inverter board needed before I will go further.

[lookimback]

Re: westinghouse vr3215

On the inverter board I have 2 wires that come from the main board. They are BK and DM. BK voltage is 2.9v and DM is 1.2v. I don't know what is normal.

OK the resistances on the high voltage side are, if I did this correctly (I tested via the solder points which lead to the ccfl connectors), 1.308k, 1.303k, 1.282k, 1.280k. As for fuses, I don't see anything I recognize as a fuse. I'm new to SMD components so if some of them are fuse I'll need you to describe them. Thanks.

[budm]

Re: westinghouse vr3215

OK, so now you do get the 24vdc to feed the inverter board? if that is the case, you will need to see if the inverter board is OK, you can check all the fuses, the resistance readings of the high voltage side of the inverter transformers, etc.

[lookimback]

Re: westinghouse vr3215

OK I put the board back in and reconnected everything. I have the correct voltages on all the terminals. I guess that brings it to either the inverter board or a bad ccfl. I took the screen out and looked at the ccfls. Here is a pic of them when I power on. They don't fully light and go out in about 1 second. I also hear a slight humming sound.

[lookimback]

Re: westinghouse vr3215

OK thanks. I'll do that and post back. Might be a couple days because I'll have to order a 5k resistor. I'm ordering some other parts from Digikey anyway.

[budm]

Re: westinghouse vr3215

Use 1K resistor between the STBY PIN and the +5stby pin.

[lookimback]

Re: westinghouse vr3215

I did the testing with the board out and disconnected. So, I'll reconnect it and test again when I get home. Are there terminals I can jump to switch the STB on? Now you got me thinking it might not be the power supply. I'll retest when I get home and post the results. Thanks!


As for test equipment , I have a Radio Shack multimeter and its worthless for anything other than checking voltage. My capacitor tester came from Amazon and also is worthless. I ordered a Fluke 115 off eBay this morning.