So I picked up a free non-working Acer H243H monitor from Craigslist a few weeks ago. It seems to turn on and has a display on the screen, but turns right back off a few seconds later. I took it apart looking for 'bulging' capacitors (Google tells me this is fairly common) on the power board but don't really see any. However, there seems to be some weird 'dust' or something covering some components in a small area of the board. I don't know what it is or what else to look for as I'm a novice. I thought maybe someone here can tell me what this 'dust stuff' is and if it's the culprit, or maybe there's something else I'm just not seeing.
Edit: Looks like the forum shrank my images quite a bit and don't have a way to see the original size, so I edited this post and attached the original files also.
Hi,
Just because there are no bulging electrolytic capacitors, does not mean they are okay.
The dust is just that, dust, attracted to the high voltage components due to electrostatic attraction and then moisture in the air, to form a bit of corrosion.
You should be able to brush it off, or use isopropyl alcohol to dissolve it.
Careful as that large central cap layig on its side will be a 400V cap, and can hold a charge for quite a while.
If you are serious about this moitor, you would be advised to get a component tester, that measures capacitor ESR.
Or just buy all the caps you need to replace all those on the board.
Usually a board starting than shutting down, indicates an overload somewhere, cap replacement is a good start.
Is the whole monitor turning off or is it just the backlight? If it's just the backlight then that's usually a sign a CFL is failing. It strikes up for a start but over current causes the backlight electronics to shut it down a couple of seconds later. As your monitor has two CFL's try disconnecting one at a time and see if the display remains visible.
If your not confident about this sort of thing then best not to attempt repair as CFL electronics are usually very high frequency & voltage.
Thanks guys for the replies. I didn't think anyone replied, otherwise I would've replied a lot sooner - I thought I was 'subscribed' to this thread with email notifications, but guess I was wrong.
So I'm assuming that 'ESR' caps are all the cylindrical ones? Maybe I'll see if I can find direct replacements online (they've gotta be cheap, right?). If I can, I'll order them and replace them.
I believe the whole monitor is turning off - the green power light turns to amber when the display goes off.
Haha, yes. I see what you're getting at - I definitely had it plugged into a working computer when I was testing. Besides, I do remember getting a picture at first.
I think the power light goes out completely. I think I was confusing this issue with another completely different computer issue. My brain ain't what it used to be...
Hmmm, could be a complex problem. Checking the power supplies are all nominal is worth doing,
as fixing a power supply isn't too complex. Any other fault may be hard/intractable.
Nominal for a power supply rail means the right voltage and without undue ripple/noise. A multimeter
on DC, then AC volts is enough to diagnose this.
Requisite care is needed with mains powered equipment once the cover is off, of course.
Hi,
When you loose picture, does the indicator light go out as well.
If not, the problem may be the backlight supply.
If you reassemble it and start it up with signal, when it goes off, use a torch/flashlight shining close to the screen, and see if you can see the image still on the screen.
Yikes! Yeah I'm not really comfortable working with AC.
I'll have to put the monitor back together and see what happens again since I don't remember exactly. And I'll try the thing with the flashlight.
Thanks for the link to the service manual. Wish I would've thought to look for that when I was taking it apart! The rest of it looks greek to me - I'm not electronics savvy.