Soldering Capacitors on LCD Monitor


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Soldering Capacitors on LCD Monitor

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robsellars
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Nov 1, 2011, 4:05 PM

Post #1 of 4 (2890 views)
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Soldering Capacitors on LCD Monitor	Can't Post

Hi

Hopefully someone here might know how to help with this and save me buying a new monitor! For the last couple of weeks Ive been trying to fix my LCD monitor and I think Im at the point where I need to take it to someone to have a look. I have a Hyundai Monitor W240D, which Ive had for 3 years.
About 4 weeks ago the screen started to flicker, then it just appeared to go black. It’s a totally dead picture. When you switch it on, you see the screen lighting up for a second, then it just switches off again.
After a bit of reading about I suspected it was to do with faulty capacitors and so I bought some more of the same ones, and replaced. This seemed to work fine for a few days, and then it went back to the same problem again. I thought I might have re soldered on some wrong so I pulled the monitor apart again, and resoldered everything. Again, it all worked for a few days again and then back to the same thing.
Ive done this a number of times now and have the same thing each time.
Do you know what could be causing this? Is it something any of you have seen before?

Thanks

Rob

jts1957
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Nov 1, 2011, 7:26 PM

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Re: [robsellars] Soldering Capacitors on LCD Monitor [In reply to]	Can't Post

Bad bulbs?

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Location: Far, Far Away

Ram Rod
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Nov 10, 2011, 2:36 PM

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Re: [robsellars] Soldering Capacitors on LCD Monitor [In reply to]	Can't Post

Sometimes electronic repair does involve guess-work. Thing that's best is to make good and semi-educated guesses. I would guess it's the inverter or lamp. I had a Toshiba laptop where the screen went out after only three years. It was the CCFL. I just bought a stand alone monitor for my laptop at that point.
As for the monitor powering on and having video for a few seconds or so, I've seen the same thing several times with the LCD TVs I have fixed. Two out of three times it's been the inverter, and once it was a bad cap on the power supply. Once the cap goes out on the power supply though....it usually won't power up the backlight at all anymore, or it will just flicker split second as the AC sine wave reaches that point and voltage is right coming out of the cap. You removing the power supply and re-installing it is just like removing power from the unit and re-booting it as a whole. What you are doing to the board when it's out likely makes little difference. So....if you know all the components on the power supply are good, then the problem lies elsewhere. If you have jumpered or shorted a connection inadvertently with your soldering that may be a different story. I also think it's important to observe correct polarity when replacing capacitors. Electrolytic capacitors have a positive and negative side. The gray stripe on the side of can denotes the negative side. Put your caps in backwards and they won't last long.
Wishing you best on your project.

robsellars
New User

Nov 10, 2011, 9:03 PM

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Re: [Ram Rod] Soldering Capacitors on LCD Monitor [In reply to]	Can't Post

Read this just after I gave in and bought a new monitor!

I think I may still try a new inverter and see if that works. It cant be the capacitors any more, Ive replace them all and still the same problem.

Cheers for the advice

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