westinghouse vr3215

[lookimback]

Re: westinghouse vr3215

510 ohms 5%. When I test it I get 518 ohms cold. I'll let it get hot and check then too.

[lookimback]

Re: westinghouse vr3215

When powered on I get 0 ohms. When hot, while cooling, I get resistance starting between 0 and 50 ohms and increasing about 3-5 ohms per second. Freeze spray has no effect other than making resistance increase faster when powered off.

[budm]

Re: westinghouse vr3215

That resistor will dissipate a little bit over 1 Watt of power. You cannot check the resistance when circuit is powered up. It is just a bleeder resistor to drain the 24V power supply when the TV is turn off and also gives a little load to the 24V power supply.

[lookimback]

Re: westinghouse vr3215

So its normal to get hot?

[budm]

Re: westinghouse vr3215

1 Watt on small body can be hot. The circuit will function without that resistor in place, you can verify that the resistor is connected in parallel with the filter cap or not by checking the connection between the legs of the cap and the resistor.

[lookimback]

Re: westinghouse vr3215

I did that, it is parallel. I figured there would be some heat since some of the energy passing through resistance is converted to heat. I just wasn't sure what was normal.
What about the SMD caps C209 and C210 not having any voltage and also not being a negative or ground? I noticed that one side of them is on the same pad as the big tab on 2 of the MOSFETs.

[budm]

Re: westinghouse vr3215

At this point I cannot tell much unless we can get the spec sheet of that PWM IC which drives those 4 MOSFETs. The inverter is just not putting out enough high voltage to drive the lamps right now.

[lookimback]

Re: westinghouse vr3215

I was trying to find the data sheet for that but no luck. I'll keep looking.

[budm]

Re: westinghouse vr3215

By the way, did you test those 4 MOSFET.
Looking at it with big tab up
pin1 = left pin (Gate)
Pin2 = biag tab (Drain)
pin 3 = Right tab (Source)
Just measure the resistance of
1 & 2 =
1 & 3 =
2 & 3 =

[lookimback]

Re: westinghouse vr3215

I had done 1 & 3 on all of them. I'll do them all when I get home from work (about 9:30 eastern time).

[lookimback]

Re: westinghouse vr3215

OK, resistances of the MOSFETs are as follows.
Amp4015p (1) closest to power connector
1 & 2 12.02m
1 & 3 9.99k
2 & 3 9.8m

Amp4010n (1) closest to power connector
1 & 2 9.98m
1 & 3 39k
2 & 3 12.06m

Amp4015p (2)
1 & 2 12.04m
1 & 3 10.01k
2 & 3 9.9m

Amp4010n (2)
1 & 2 11.95m
1 & 3 42.3k
2 & 3 10.10m

[budm]

Re: westinghouse vr3215

Well,, they do not have any very low resistance value at all. I really do not know what else for you to test at this point, running out of Idea.

[lookimback]

Re: westinghouse vr3215

My ESR meter got delivered today. I'll go pick it up tomorrow.

[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.

[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?

[tom66]

Re: westinghouse vr3215

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

[lookimback]

Re: westinghouse vr3215

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

[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

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.

[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.