Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

[retiredcaps]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Hi everyone! I too have a Westinghouse L2410NM 24" and the back light has begun turning on and off intermittently.

Do you have a multimeter?

When the lights turn off/on intermittently, can you measure the secondary voltages to see if they are fluctuating? The voltages to the inverter will either be 14.5V or 24V DC.

[retiredcaps]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

The brown capacitors appear to be Chemi-Con (the empty rectangle logo). I don't know the brand of the capacitors on the inverter board.

Yes those are United Chemi-con caps. They are a reputable brand capacitor.

The ones on the inverter look like Capxon? If they are Capxon, they are not so reputable.

But before replacing anything, let's do the voltage measurements and some other tests.

[JoseJX]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Here are the higher resolution photos, sorry, I thought the directions said to make them lower resolution.

I don't think I can remove the heat sinks easily. They're riveted and soldered on. I'd prefer to hold off on bending them away unless it's required.

I do have a multimeter, but the LCD hasn't turned off since I took the back of the screen off. The period that it does turn off is really short as well, less than a second or two, so I think it might be tough to get a measurement.

Thank you!

[retiredcaps]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

I do have a multimeter, but the LCD hasn't turned off since I took the back of the screen off.

Maybe you can carefully use a hot air gun/blow dryer to warm up small areas at a time?

[JoseJX]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Hmm, maybe it's not heat related, I'm a bit confused now? I tried heating the power supply with a hair dryer, my infrared thermometer reads 70-75C, but it's still not turning off. Sorry, I'll try again later tonight if you have another idea. Perhaps it was just a loose connection? I'm still concerned with the power supply whine though.

[retiredcaps]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Perhaps it was just a loose connection? I'm still concerned with the power supply whine though.

I did suggest to look at your solder connections. The whine could be a bad cap or from the transformer. Others have more expertise in identifying this.

[jetadm123]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Here are the higher resolution photos, sorry, I thought the directions said to make them lower resolution.

I don't think I can remove the heat sinks easily. They're riveted and soldered on. I'd prefer to hold off on bending them away unless it's required.

I do have a multimeter, but the LCD hasn't turned off since I took the back of the screen off. The period that it does turn off is really short as well, less than a second or two, so I think it might be tough to get a measurement.

Thank you!

This definately falls in the category of the worst power supply design! Those heatsink covers make it extremely difficult to troubleshoot the supply, since we can't point out components for you to test. We also have to see the top portion of the board to relate it to what's on the bottom portion of the board. If you could take a snapshot of the the heatsink assembly, maybe someone can suggest a less painful way to remove it.

[Minathevi]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

I'm having the exact same issue with my Westinghouse. It also has the same model power supply as JoseJX. I've included a picture of the board with one of the heatsinks removed. I don't have access to my soldering station at the moment and I'm not about to break the other one off.

[retiredcaps]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

I'm having the exact same issue with my Westinghouse.

Please clarify. Once the thread runs 3 pages long with 5 or 6 posters, it gets confusing.

[Minathevi]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Please clarify. Once the thread runs 3 pages long with 5 or 6 posters, it gets confusing.

My apologies. The backlight turns on and off intermittently like JoseJX described in his post. I can hear a faint buzzing, but none of the caps appear bulging and there's no change to the sound that I can hear when the backlight turns off and back on.

[jetadm123]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

My apologies. The backlight turns on and off intermittently like JoseJX described in his post. I can hear a faint buzzing, but none of the caps appear bulging and there's no change to the sound that I can hear when the backlight turns off and back on.

Can you please give us a top/bottom photo of the entire power board?

[Minathevi]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Can you please give us a top/bottom photo of the entire power board?

Delivered

[alexanna]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

This monitor looks to have six ccfl tubes and six transformers.
Could this be a monitor we could plug one ccfl at a time,to see if anything jumps out at us?
[Totally failed bulb,Bad transformer or circuitry ect. ect.]
Al.

[jetadm123]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Delivered

I've marked in red what look to be 3 fuses, marked FZX? Can you check those for continuity? If they check out ok, have you tried measuring the voltages at the two wiring harnesses? It doesn't look like any of the wiring is labled with what each wire is for.

I also marked in yellow a 8-pin PWM chip. Can you read off the part number?

Flickering does sound like a bad cap problem and a cap doesn't have to bulge to be bad. Also a bad CCFL lamp/wiring can cause that problem.

[JoseJX]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

On my monitor, the fuses are all intact. That chip is marked with "4419 BA6515" and a logo that could be "Alpha and Omega Semiconductor", but it's hard to make out on my chip. A&O does have a part with a 4419 marking, it's a P-FET and it's in an 8 pin package like this part. I haven't been able to find out more.

What do you want us to measure exactly on the wiring harness?

As an aside, I haven't had any flicker since I pulled the monitor apart. I did also pull and re-plug the CFL wiring and made sure that all of the wiring harnesses were solidly connected.

[alexanna]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

As an aside, I haven't had any flicker since I pulled the monitor apart. I did also pull and re-plug the CFL wiring and made sure that all of the wiring harnesses were solidly connected.

Something to try,
With the monitor apart try to position the LCD as it would normally be positioned. I have found problems with ccfl wiring may take much longer to present with the panel laying flat.In its normal position heat will rise and cause a problem to occur much quicker.
Al.

[jetadm123]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

On my monitor, the fuses are all intact. That chip is marked with "4419 BA6515" and a logo that could be "Alpha and Omega Semiconductor", but it's hard to make out on my chip. A&O does have a part with a 4419 marking, it's a P-FET and it's in an 8 pin package like this part. I haven't been able to find out more.

What do you want us to measure exactly on the wiring harness?

As an aside, I haven't had any flicker since I pulled the monitor apart. I did also pull and re-plug the CFL wiring and made sure that all of the wiring harnesses were solidly connected.

Another member, Minathevi, also entered this thread with the same model model monitor. Therefore, this can add some confusion because members are not sure who's talking to who and may wind up perfoming unnecessay tests.

AP4419 spec found here:

http://www.alldatasheet.com/view.jsp?Searchword=AP4419

Definitely sounds like a heat related problem, since taking off the cover allows more air flow past the board and reduces heat build up.

The fuse and harness measurement tests were really meant more for Minathevi, since it looks like you're getting an image without flicker, which means the voltages are probably ok.

Possible problem could be bad caps because those heatsink covers really contain the heat and basically "cook" the caps along with the other components.

Another problem could be a bad solder joint. As the the board heats up, it will flex a little and that could cause the joint to open up. Try looking for bad joints, especially around the transformers and touch them up with your soldering iron and fresh solder.

Also, I've seen flickering caused by bad caps on the the logic board. Because of the smaller footprint on the logic board, the manufacturer will "shove" large cap values into a physically small can, which over time dries out. Try heating up the logic board with your blow dryer to see if you can recreate the flickering problem.

[jetadm123]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

Another member, Minathevi, also entered this thread with the same model model monitor. Therefore, this can add some confusion because members are not sure who's talking to who and may wind up perfoming unnecessay tests.

AP4419 spec found here:

http://www.alldatasheet.com/view.jsp?Searchword=AP4419

Definitely sounds like a heat related problem, since taking off the cover allows more air flow past the board and reduces heat build up.

The fuse and harness measurement tests were really meant more for Minathevi, since it looks like you're getting an image without flicker, which means the voltages are probably ok.

Possible problem could be bad caps because those heatsink covers really contain the heat and basically "cook" the caps along with the other components.

Another problem could be a bad solder joint. As the the board heats up, it will flex a little and that could cause the joint to open up. Try looking for bad joints, especially around the transformers and touch them up with your soldering iron and fresh solder.

Also, I've seen flickering caused by bad caps on the the logic board. Because of the smaller footprint on the logic board, the manufacturer will "shove" large cap values into a physically small can, which over time dries out. Try heating up the logic board with your blow dryer to see if you can recreate the flickering problem.

I reread your initial description of the symptoms and please disregard my last suggestion concerning the logic card.

[Minathevi]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

On my board the fuses are also intact. The PWM you mentioned is P/N 4419 BA6116 and it also appears to be an Alpha Omega Semiconductor chip. The solder joints on the Power Supply board look good. I just cleaned up the residual flux. As far as the wiring harness is concerned, I wouldn't have the slightest clue where to begin. When I get a chance I'll just take readings on all of them in sequence.

[jetadm123]

Re: Westinghouse L2410NM 24" LCD power goes on and off, blue light flickers

On my board the fuses are also intact. The PWM you mentioned is P/N 4419 BA6116 and it also appears to be an Alpha Omega Semiconductor chip. The solder joints on the Power Supply board look good. I just cleaned up the residual flux. As far as the wiring harness is concerned, I wouldn't have the slightest clue where to begin. When I get a chance I'll just take readings on all of them in sequence.

Unfortunately, this is one of those power supplies they don't want you to work on as evident by the riveted heatsink covers and that the wiring harness has no silkscreened listing of what each wire does.

More importantly, in post #55, JoseJX reports that since removing the cover, he has not experienced any flicker. Are you encountering the same results?