westinghouse vr3215

[lookimback]

Re: westinghouse vr3215

Well, I didn't have a way to test the lamps so I used different lamps to test the inverter. Different lamps didn't fully light either. Definitely the board that's bad.

[lookimback]

Re: westinghouse vr3215

I think I'm on to something. I have 6.87v on pin 11 (VDDA) and pin 15 (ENA). Data sheet says 7v between pin 11 and ground. So the chip gets power and is enabled. Pin 4 is voltage sensor (VS). If voltage above 3v is sensed, chip shuts down. Voltage on pin 4 is 2.7v. I removed the cap that is in series with VS pin and chip still shut down. I think the problem is with pin 1. Pin 1 (CS) is the lamp fail safe. "If voltage on CS pin is less than 350mv, the IC will initiate the striking timer. An internal constant 3.0ua current source starts to charge the capacitor connected to STIME pin. Voltage higher than 3.0v at STIME pin indicates an ignition timeout. Under such circumstances, PWM Gate outputs are disabled and thus power switches are turned off." Thats quoted from page 8 of the data sheet. Now, I have 6.75v on the STIME pin and 0v on the CS pin. That would indicate that the lamp fail safe circuitry is causing the shut down. So now I need to determine if all the CCFLs are good, then, if they are good, the problem will be in the CS circuit. I guess now, what I need to know, is how to safely test the lamps?

[lookimback]

Re: westinghouse vr3215

I think these are the data sheets. 2 days looking and no luck then I search OB3328 PDF and find it on first page of search results.

[lookimback]

Re: westinghouse vr3215

Just a long shot but I tried emailing the company that makes the PWM IC. Hopefully they can send me a data sheet.

[lookimback]

Re: westinghouse vr3215

Caps in series with the PWM ic are as follows:
Some I can't get capacitance in-circuit.

Pin 1 ESR over 40
Pin 2 open circuit or low capacitance
Pin 3 2.03uf 12ohms
Pin 4 open circuit or low capacitance (reverse probes and it says ESR over 40 ohms.
Pin 5 no caps
Pin 6 2 caps 0.86uf, 1.10 ohms, cap 2 open circuit or low capacitance
Pin 7 open circuit or low capacitance
Pin 8 no caps
Pin 9 open circuit or low capacitance
Pin 10 no caps
Pin 11 no caps
Pin 12 open circuit or low capacitance
Pin 13 no caps
Pin 14 open circuit or low capacitance
Pin 15 0.78uf ESR 1.16 ohms (other side of cap connects to pin 6)
Pin 16 no caps

[lookimback]

Re: westinghouse vr3215

There's other caps around the PWM IC that I get "open circuit or low capacitance" message from

[budm]

Re: westinghouse vr3215

The ESR is higher than I thought.

[lookimback]

Re: westinghouse vr3215

I spent about 2 hours last night looking for it. There's no other way to figure out which pin it is? C209 2.35uf, ESR 12 ohms. C210 2.37uf, 12 ohms.

[budm]

Re: westinghouse vr3215

I wish I can find the spec of that PWM IC, there is a 3-second timing pin controller that shutdown the circuit if there is the problem, if we defeat it then it will stay on for us to probe the voltages.

[lookimback]

Re: westinghouse vr3215

I ordered a board from eBay this morning. $32. I'm still hoping to figure out what's wrong with this one and, if I fix it, sell it back on eBay. In any event, I'm learning a lot from this. I'll take out one of the caps and test both again.

[budm]

Re: westinghouse vr3215

Just take one out, it is non-polarized cap. Do you consider buying the replacement board? One thing for sure is that if you monitor the 24v, it does stay around 24v or so and not dropping down to less than 20V?

[lookimback]

Re: westinghouse vr3215

I measured them in the board. Should I take them out? Also, do they have polarity? Several other SMD caps do say "open circuit or low capacitance" when I test them.

[budm]

Re: westinghouse vr3215

I am looking for very low capacitance if the caps are bad something like less than 1uF. Did you measure them out off the board because the value is way too high for the cap that size?

[lookimback]

Re: westinghouse vr3215

OK, I read the instructions that came with the ESR meter. It wasn't telling me the caps were bad. It was saying in circuit/leaky because it couldn't read the capacitance. So, the DC blocking caps both read 370uf 0.06 ohms. They are parallel so this doesn't really tell me if one is bad.

[lookimback]

Re: westinghouse vr3215

C209 and C210? I tested them and the meter didn't say they were bad. I'll test them again and post the ESR when I get home tonight.

[budm]

Re: westinghouse vr3215

There are two SMD DC blocking caps in series with the primary side of the inverter transformer (see the SCH I posted), if they are bad, it will also cause the transformers not be driven correctly.

[lookimback]

Re: westinghouse vr3215

I have a Peak Atlas ESR70. I couldn't get it to work on the little blue ceramic caps either.

[tom66]

Re: westinghouse vr3215

Ceramic cap marked 104 will not accurately test on most ESR meters.

[lookimback]

Re: westinghouse vr3215

I got my ESR meter and tested the cap I replaced. Its got an ESR of 0.10 ohms. The meter is telling me its leaky. Maybe that cap won't work after all. I have some Panasonic FCs coming. The cap I took out had an ESR of 0.06 ohms.

Edit: The small tan cap that is parallel with the big resistor has an ESR of 0.37 ohms. The meter says its leaky. It is marked 104. What size would that be for a replacement?

[lookimback]

Re: westinghouse vr3215

Well, I didn't want to have to buy a new inverter board but I have a buyer waiting on me so I didn't have much choice. Got lucky and found one on eBay for $32 with free shipping. I think with a working board for a reference we might be able to figure out the other one. In any event, I've learned more from this TV than all the others combined.