westinghouse vr3215

[lookimback]

Re: westinghouse vr3215

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

[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

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

[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).

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

[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 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

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

So its normal to get hot?

[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

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.

[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.

[budm]

Re: westinghouse vr3215

What is the value of that big resistor? It is hooked as a bleeding resistor (it is connected to the 24V+ and Ground) per my drawing. There will no DC across the primary side of both transformer due to the DC blocking caps, but there will be high frequency AC on the primary side.

[lookimback]

Re: westinghouse vr3215

So I did some live testing on the inverter board and think I made some valuable observations. 1, there is no power to the common side of the HV transformers. I think we already knew that though. 2, I have either positive or negative voltage on every terminal of the PWM IC, I don't know what those voltages should be but figure, since there are no terminals which are just nothing, that its probably working. 3, I have neither positive or negative voltages on either side of caps C209 and C210. 4, the big resistor on the top side of the board gets hot enough to burn you. This I found by chance when I was done and went to pick up the board. I hope some of this makes sense to someone reading this.

[lookimback]

Re: westinghouse vr3215

It didn't work. At least we eliminated that as a possibility. I did order a really good ESR meter from eBay. I'm sure that will help with future projects. I've been trying to find a data sheet for the SMD PWM IC, so I can try to figure out how to test it, no luck though.

[lookimback]

Re: westinghouse vr3215

If it works I'll order some FCs and replace them right away.

[tom66]

Re: westinghouse vr3215

They should work for testing, but I would expect only a year or so before they fail.

[lookimback]

Re: westinghouse vr3215

I do have these that I ordered by mistake. They are 35v 470uf. I wouldn't leave them in but would they be OK just to test it?

[budm]

Re: westinghouse vr3215

You can solder in another cap that you have, larger value is OK just to see if it makes any different.