Another Westinghouse LCM-22w2 (Shuts off)

[sircanegiem]

Model: Westinghouse LCM-22w2
Power board: Delta DAC-19M009

Hello everyone, I just bought one of these on ebay that shuts off after about 5-10 seconds of being powered on, and stays turned off until I unplug it from the wall for a few mins and plug it back in again, then the problem repeats. I have checked the board's capacitors and it appears they have already been replaced with Panasonic caps.

I haven't done anything to an LCD power board before besides replacing the caps (never tested components) so does anyone have some ideas of what to test for problems? I have a digital multimeter with ACV/DCV/DCA/Ohms/arrow-pointing-to-a-line functions.

I also have another one of these exact same monitors that I'm using on my own computer, if comparing the two could help me troubleshoot it, but I'd prefer to not have to tear it apart if possible!

Note: I noticed a quiet ticking sound from the area circled in green, seen in the first picture.

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

I plugged it in again and took another listen, and it sounds like the ticking sound might actually be coming from the area just to the right, possibly from a transistor, but it's really difficult to tell.

If I were to try and replace the four transistors on this board, how would I find out which ones to replace them with?

[PlainBill]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Check the solder joints around the SMPS transformer. Also, it would be a good idea to replace the cap that the original person missed (at 7:00 in the circle). I'd suspect a bad solder joint on one of the diodes around the SMPS transformer.

PlainBill

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Looking around the transformer I don't see any fractures in the solder; some of the joints look more dull than others but looks normal besides that.

I was testing the transistors and shorted one out though (it sparked - whoops!) on the left side of the green circle. On the lower two legs, the voltage was flying all over the place (-150v to 400v on my digital multi) and I can't remember the other two because one of the leads slipped and now it doesn't read anything... looks like I'll need to find a replacement :P

How does one figure out the specs of a transistor? The markings on the one I shorted are:
P10NK60KFP
GK18P V6
CHN 626

Edit: I also checked the voltage at the big capacitor and was getting about 165V. Fuse is getting 20.5 volts.

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Okay, so I jumped ahead and found three of the four exact transistors on Digikey, but the fourth one isn't there.
The datasheet for it is here.
Can PlainBill or anyone with some knowledge of this please link me to a compatible part? (digikey preferably)

I also replaced the cap the last person missed; had a few left over from repairing my own LCM-22w2.

[jetadm123]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Looking around the transformer I don't see any fractures in the solder; some of the joints look more dull than others but looks normal besides that.

I was testing the transistors and shorted one out though (it sparked - whoops!) on the left side of the green circle. On the lower two legs, the voltage was flying all over the place (-150v to 400v on my digital multi) and I can't remember the other two because one of the leads slipped and now it doesn't read anything... looks like I'll need to find a replacement :P

How does one figure out the specs of a transistor? The markings on the one I shorted are:
P10NK60KFP
GK18P V6
CHN 626

Edit: I also checked the voltage at the big capacitor and was getting about 165V. Fuse is getting 20.5 volts.

The PWM mosfet you shorted out is probably the one below:

http://search.digikey.com/scripts/Dk...=497-5892-5-ND

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

The PWM mosfet you shorted out is probably the one below:

http://search.digikey.com/scripts/Dk...=497-5892-5-ND

Whoops, misspelled the code on it, it is indeed the STP10NK60ZFP you linked! (shorting it wouldn't have damaged anything else would it? :S)

[seanc]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Are those actual pictures of your power supply in its current state?

None of those caps are Panasonic...

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Are those actual pictures of your power supply in its current state?

None of those caps are Panasonic...

Sorry, should have cleared that up. Two of them are panasonic, one nichicon, one samyoung NXC, and the rest huang (never heard of 'em, but physically they look OK). The biggest cap is the original Capxon capacitor. I emailed the seller now and he replied saying the caps were replaced just six months ago or so.

[seanc]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Right, so the pictures aren't of your power supply then?
If that is a picture of your power supply, any of those that say Panasonic are fake.
Panasonic capacitors always have a T style vent.

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Wow good call, didn't even think about the vents. That is the actual picture of the power supply and those are definitely fake pannys with X vents. I'll go ahead and take apart my own LCM-22w2 and recap it (again) with the exact same ones I put in mine and try my luck again after the new transistors arrive. Should be here on Saturday or so; will post then.

[seanc]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Well if you can post what type you used in your existing monitor, it would be check that they're a good match.

This power board looks very similar, if not the same as the one I have in my Viewsonic 22" LCD. It's working fine with Panasonic FM, although I will shortly be replacing those with FK to see if it alleviates a whine that it makes in standby.

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

In my own monitor I replaced the caps with Nichicon PW and HE, and I think a Chemi-Con KZE or two. And from my research there were some varieties of this board used in Viewsonic and Acer monitors too.

[sircanegiem]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Hey everyone, just wanted to give an update. Replaced the transistors, but the power board was still shot. I ended up just buying another power board instead from someone selling an LCM-22w2 on Ebay ($30) and that fixed the problem -- but only for about 20 minutes!

"Uhh... what?"

When I first turned the screen on, the top CCFL was very pink, and then gradually cleared up after about a minute or two. After it cleared up I thought all was well, until the monitor suddenly shut off 20 minutes later; no backlight at all, and only the green power light to show it was even still getting power.

Turns out *another* common problem with these is that upper CCFL. When it wears out, the inverters cut the power going to both it and the bottom CCFL as a safety feature and the backlight is no more. The only fix is to get another pair of tubes, but if I did that the monitor wouldn't be worth the cost anymore.

I'm selling both the working inverter board and the faulty one as a pair on ebay so I'm not out more than $20-30 for the project. Thanks for everyone who helped and I hope this summary of my findings helps someone else. If buying a used LCM-22w2, make sure to ask the seller if any previous repairs have been done to the monitor, and if there's a pink tint to the screen on a cold startup, to avoid the same issues I had!

[jetadm123]

Re: Another Westinghouse LCM-22w2 (Shuts off)

I'm selling both the working inverter board and the faulty one as a pair on ebay so I'm not out more than $20-30 for the project. Thanks for everyone who helped and I hope this summary of my findings helps someone else. If buying a used LCM-22w2, make sure to ask the seller if any previous repairs have been done to the monitor, and if there's a pink tint to the screen on a cold startup, to avoid the same issues I had!

This is really good advice. Also, watch out for sellers that look to be in the repair business. Hint: sometimes in the background of their photos, you see a bunch of test equiptment on a workstation or tool bench. Or, look at the other photos of the other items they're selling; if it's all busted monitors, watch out and ask questions. Also, the seller's Ebay id, ie; MyRepairShop123, would be a good clue. You can figure that monitor's been opened and "played with" and is probably beyond the scope of just replacing caps. It's probably something major like replacing CCFL tubes, a burned out transformer, bad controller or mosfet (which may be impossible to find or very expensive), which makes your "great buy" beyond economical repair. This is the old ploy of trying to stick someone else with junk they couldn't repair. If they could repair it cheap, then they would have done so. I'm sure other members here have their share of horror stories concerning a monitor purchased off of Ebay.

[Rtech]

Re: Another Westinghouse LCM-22w2 (Shuts off)

Jetadm123...The thing I detest,is when they say ...UNTESTED...its common sense to try a Monitor, to see if it works,for one reason only...A WORKING Monitor re-sells for a lot more cash than a broken one....so would you test OR not test....its a no-brainer for me.