Westinghouse 37" LVM37w3 troubleshooting.

[PlainBill]

Re: Westinghouse 37" LVM37w3 troubleshooting.

Capxon KF and GL
Teapo A3, other one I can't identify due to being next to a heatsink.
Taicon M
2x Rubycon YXG
There's another one with no name but it's 35V 470uF has KZH, color is brown.

I'll buy zener and the caps, it might be week or two if I use USPS.

IIRC, you are in the USA. If you order online, specify USPS First Class Mail. Shipping will cost unser $30 for a typical order and if you order this weekend you should have the parts Wednesday.

PlainBill

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

So I was feeling lazy on the weekend, didn't order.

I'm ordering it today, but I came to question the rubycon yxg 25v 100uF, should I replace them? Teapo, Taicon and Capxon are a given, but I heard great things about rubycon so should I replace them?

edit: Also Does teapo boost their specifications? I seem to having hard time finding matching ripple current. Teapo SC series both 50v, one is 4.7uF and other is 10uF.
4.7uF = 115 ripple, I assume milliamps, but the close thing to it is 95mA Panasonic FC.
10uF = 140 ripple, Close thing is Panasonic FC @ 125.

If I go up in voltage, I don't get any closer to hitting teapo specs, so I assume that they are padding the specs to make them look good?

[PlainBill]

Re: Westinghouse 37" LVM37w3 troubleshooting.

So I was feeling lazy on the weekend, didn't order.

I'm ordering it today, but I came to question the rubycon yxg 25v 100uF, should I replace them? Teapo, Taicon and Capxon are a given, but I heard great things about rubycon so should I replace them?

edit: Also Does teapo boost their specifications? I seem to having hard time finding matching ripple current. Teapo SC series both 50v, one is 4.7uF and other is 10uF.
4.7uF = 115 ripple, I assume milliamps, but the close thing to it is 95mA Panasonic FC.
10uF = 140 ripple, Close thing is Panasonic FC @ 125.

If I go up in voltage, I don't get any closer to hitting teapo specs, so I assume that they are padding the specs to make them look good?

Don't worry about the ripple current specs on the small caps; they aren't filtering high current outputs like the larger caps. The 4.7 and 10 uF caps are critical because they often dry out and are critical for start up of the SMPS controller.

As far as the Rubycon cap, Rubycon has a very good reputation. It's your call. Personally, I'd replace it because I hate worrying that I missed something that will come back to bite me.

PlainBill

[retiredcaps]

Re: Westinghouse 37" LVM37w3 troubleshooting.

As far as the Rubycon cap, Rubycon has a very good reputation. It's your call. Personally, I'd replace it because I hate worrying that I missed something that will come back to bite me.

Rubycon does have a good reputation, but a Panasonic FR costs only 33 cents. So it seems like a good call to replace it.

http://search.digikey.com/scripts/Dk...name=P14413-ND

FC costs 34 cents

http://search.digikey.com/scripts/Dk...name=P10269-ND

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

I'll buy FR for the rubycon, just in case and hold off on replacing them. FC for the small caps.

should I replace D11 and D12 diodes?

D11 is on the first leg of the transistor circuit after ZD1 and D12 is on the second leg of the transistor circuit. Since I'm already replacing zeners, would it be good idea to replace the D11 and D12 too? Or wait and see?

Just want to make sure, because I don't want to pay for second shipment if I don't need too.

d12 is BYV2, but glue is blocking the rest, it's hard to remove, below the 2 is a zero.

[PlainBill]

Re: Westinghouse 37" LVM37w3 troubleshooting.

I'll buy FR for the rubycon, just in case and hold off on replacing them. FC for the small caps.

should I replace D11 and D12 diodes?

D11 is on the first leg of the transistor circuit after ZD1 and D12 is on the second leg of the transistor circuit. Since I'm already replacing zeners, would it be good idea to replace the D11 and D12 too? Or wait and see?

Just want to make sure, because I don't want to pay for second shipment if I don't need too.

d12 is BYV2, but glue is blocking the rest, it's hard to remove, below the 2 is a zero.

Use the diode test function on your DMM. Test the diode by touching the leads to the ends of the diode - red to the banded end. Now reverse them - black to the banded end. If you get a reading of less than 1 (typically .5) when the black lead is on the banded end and a reading of OL when the red lead is on the banded end, the diode is probably good. If it reads 0 in both directions you will have to remove the diode and retest. If they test good, there is no need to replace them.

PlainBill

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

D12 tested ok, D11 on the hand is getting interference from being in circuit. I could remove it but it's glass diode that is glued. I could destroy it during the extraction process.

In one of previous picture band color is Black followed by Pink. If I look at it, I can't tell if it's brown or pink. So how can I identify this?

[PlainBill]

Re: Westinghouse 37" LVM37w3 troubleshooting.

D12 tested ok, D11 on the hand is getting interference from being in circuit. I could remove it but it's glass diode that is glued. I could destroy it during the extraction process.

In one of previous picture band color is Black followed by Pink. If I look at it, I can't tell if it's brown or pink. So how can I identify this?

What resistance do you read across D11? if it's 120 ohms, the diode is probably good. It's probably a high speed switching diode like a 1N4148. I'll do some research.

Awww, crap!!! I just spent 20 minutes searching various schematics for a possible ID of that diode. Most of them didn't show a resistor-diode pair like that. Those that did either didn't ID it, didn't have a parts list, or said 'not used'. Then I FINALLY did find one. It's a 1N4148

Digikey 1N4148WXTPMSCT-ND should work for you.

PlainBill

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

.120 both ways, not sure if it suppose to be like that since it is in parallel with the resistor above.

I'm gonna finish placing the order, I'll add the diode so I have it on hand.

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

Parts came today, I guess I'll start putting it back together. Do zeners have a polarity requirement or can they just be install no matter what orientation?

[Dgtech]

Re: Westinghouse 37" LVM37w3 troubleshooting.

Yes, there is a polarity to zenor diodes.

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

I think I'm gonna start soldering this thing back together today, how can I tell which side of the zener is ground? is there like a notch or band or something to tell me?

edit: never mine there is ridge on one side it was hard to see through the packaging. SO I guess ground goes on left where large red band on zener in the previous pic goes even though the trace on right goes to ground. Am I correct?

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

correction again... I tested the old zener and found that big red band is indeed ground and the new one has a very thin ridged band and testing it with the diode setting on my dmm I was able to figure it out, that was ground.

BRB going to solder...

[Dgtech]

Re: Westinghouse 37" LVM37w3 troubleshooting.

Before powering up, make sure you check the datasheet for correct polarity. Datasheets help reduce the guess-work.

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

I didn't find anything about polarity in the data sheet.



I was wondering if a 40 watt appliance light bulb would work when I'm testing it?

Also sometime during the winter I had the set cover up pretty good with the plastic housing on, and I think one of my cats or both of my cats got under there, I now I have tons of flea dirt everywhere, on inverter board, metal and everything. Is this going to cause a problem? How can I clean it?

[Dgtech]

Re: Westinghouse 37" LVM37w3 troubleshooting.

You're definitely not mistaken. There is no info on polarity in there so I'm kinda baffled myself. Someone else will weigh in soon and help out with this.

[PlainBill]

Re: Westinghouse 37" LVM37w3 troubleshooting.

I didn't find anything about polarity in the data sheet.



I was wondering if a 40 watt appliance light bulb would work when I'm testing it?

Also sometime during the winter I had the set cover up pretty good with the plastic housing on, and I think one of my cats or both of my cats got under there, I now I have tons of flea dirt everywhere, on inverter board, metal and everything. Is this going to cause a problem? How can I clean it?

Usually we say a diode conducts in only one direction. That is misleading; if you hook it up backwards and increase the voltage high enough it will begin to conduct - with spectacular results if you don't limit the current.

A Zener diode is a diode that has been manufactured and selected to have precise conduction characteristics in the reverse direction. Where a normal diode might be able to withstand 100 or even thousands of volts in the reverse direction, a Zener is usually designed to withstand only a few volts.

A conventional diode has a band at the cathode end - it conducts when the anode is about) .7 volts positive with respect to the cathode. A zener diode uses the same convention. If you connect the banded end to ground and apply +20 volts through a 1K (or large) resistor, it will conduct at the rated zener voltage - 15 volts in this case if I recall correctly.

OR you can use a DMM with a diode test function. With a conventional diode the diode test will show a reading when the black probe is on the banded end. With a zener diode it should show a reading when the red probe is on the banded end.

Using a 40 watt bulb for the initial tests is a very good idea.

As far as cleaning up the cats mess, I'd suggest using a paint brush to loosen the dirt and compressed air to blow it toward the cats.

PlainBill

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

uh oh... black probe was on the banded end and I got reading when the red probe was put on the other end. But on the glass one the black probe was on the thick red band end and red probe was on the green end. Anyways I set it up the same way which ever the black probe was on the new zeners it was the only way to tell.

[Mad_Professor]

Re: Westinghouse 37" LVM37w3 troubleshooting.

Well I tested it, nothing crazy happened, the bulb came on then went off.

Now what?