LG M228WA-BZ mistery no sound

[Half-Saint]

I got an LG M228WA-BZ monitor last month. The power supply was shot (black burn marks and some components missing - burned off) and all of the caps were bulging. The video PCB had one bad cap (470uF 25V). By stroke of luck I got a similar 19" LG monitor with a power supply that worked and appeared to be identical. I just had to change the bad cap on the video PCB and the LCD worked. There are two more caps of the same type which appear to be good so I decided to ignore them just for the time being because I don't have any more 470uF 25V caps in stock.

However, the first day, no matter what I did, sound wouldn't work - speakers or headphones. The power LED was also off the whole day. Today, suddenly everything works including the power LED.

Any idea what's happening here? Ghost in the machine?

Cheers,
Bojan

EDIT: I forgot to mention, the power supply was recapped by someone who replaced all 4 caps with 1000uF 35V. Two were originally 680uF 25V and two were 1000uF 25V. I replaced two of the new caps with 820uF 25V and left the other two in place.

[selldoor]

Re: LG M228WA-BZ mistery no sound

not sure if you have a problem or not.
However regarding the 4 35v1000uf caps you dont say which 2 you replaced
with 25v820uf caps.
If it was the two that were originally 25v 680uf that is ok but if you rplaced the two that were 25v1000uf then that would be a bad idea.

If you need more help with this machine please post good clear pictures of your boards using manage attachments

[Half-Saint]

Re: LG M228WA-BZ mistery no sound

OK, just a quick update. I've been running it two days now without a problem (8 hours each day). Today, I start the PC, monitor works, sound works but the power LED is only very slightly flashing randomly. I probably won't have time to disassemble it today but next week for sure.

Cheers

[Half-Saint]

Re: LG M228WA-BZ mistery no sound

Question: the video PCB uses some Sam Young KMG caps and I have trouble understanding the datasheet. To be precise, can't find any data on impedance, only ripple current. I'm trying to figure out, if I can use Rubycon ZLJ caps in place of KMG caps. Ripple current in ZLJ is almost twice as high but that seems to be acceptable. What about impedance?

https://cdn.badcaps-static.com/pdfs/...3ee2b26bd9.pdf
https://cdn.badcaps-static.com/pdfs/...86908a9c19.pdf

Cheers

[selldoor]

Re: LG M228WA-BZ mistery no sound

On monitors I dont usually think too much about ripple and ESR If they will physically fit
I just buy panasonic FC FM and FR. Chances are they are better spec than whatever was in.

[LGElectronics]

Re: LG M228WA-BZ mistery no sound

I got an LG M228WA-BZ monitor last month. The power supply was shot (black burn marks and some components missing - burned off) and all of the caps were bulging. The video PCB had one bad cap (470uF 25V). By stroke of luck I got a similar 19" LG monitor with a power supply that worked and appeared to be identical. I just had to change the bad cap on the video PCB and the LCD worked. There are two more caps of the same type which appear to be good so I decided to ignore them just for the time being because I don't have any more 470uF 25V caps in stock.

However, the first day, no matter what I did, sound wouldn't work - speakers or headphones. The power LED was also off the whole day. Today, suddenly everything works including the power LED.

Any idea what's happening here? Ghost in the machine?

Cheers,
Bojan

EDIT: I forgot to mention, the power supply was recapped by someone who replaced all 4 caps with 1000uF 35V. Two were originally 680uF 25V and two were 1000uF 25V. I replaced two of the new caps with 820uF 25V and left the other two in place.

Hi, we would be happy to help. Please contact us through private message for assistance. ^BW

[budm]

Re: LG M228WA-BZ mistery no sound

You can't go wrong with PANASONIC FM/FC/FR series.

[Half-Saint]

Re: LG M228WA-BZ mistery no sound

Still waiting for a reply from LGElectronics.

[selldoor]

Re: LG M228WA-BZ mistery no sound

Still waiting for a reply from LGElectronics.

Well that will be interesting - not. So far all he (They)??? LG SERVICE CENTRE??? USA???) have done it tell members to contact their local service centre where no doubt they will charge a hefty fee just to look at it.

Hmmm US HQ is in new Jersey - what a coincidence -Think I will have a word with TC
depending on what the response to you is.

[Half-Saint]

Re: LG M228WA-BZ mistery no sound

As long as it's working, I'm happy. I can live with a non-functional power LED Maybe I'll replace the other two 470uF 25V caps just to be safe and that's it.

[Half-Saint]

Re: LG M228WA-BZ mistery no sound

No response from the user LGElectronics. Why am I not surprised?

[Half-Saint]

Re: LG M228WA-BZ mistery no sound

More than a year later, the monitor is still working. I recently replaced the remaining two 470uF 25V on the main logic board but it doesn't change the symptoms of the power LED not lighting up. Any ideas? It's an annoyance and although I can live with it, I'd rather solve the problem.

[Half-Saint]

Re: LG M228WA-BZ mistery no sound

UPDATE:
I got a 2nd monitor of the same type, again from the dumpester. This time the caps are okay but the LCD panel has a problem. I swapped the guts from my first monitor and it was the same so I know it's not the circuitry. Both monitors have the blue LED not lighting up when on issue.

[Agent24]

Re: LG M228WA-BZ mistery no sound

Have you checked the LED itself?
Does it have power? Is it blown or shorted? If it's on the end of a cable, is the cable OK?