One of our monitors has failed

December 5, 2009 1:52 AM

One of our monitors has failed.

This is a follow-up to this question. I didn't get it repaired at the time and simply replaced it. I stored the monitor in a cold, dry room.

Yesterday I wondered if it would work again, so I brought it back into the living room and connected it up with all its original cables. And it worked for the whole night. But come this morning and it's broken again; the light on the power brick goes out as soon as it's connected to the monitor.

Given this, is the answer offered in the previous question still the most likely cause of failure? I wondered (in my non-techie way) if it might be to do with heat, since the screen itself has no vents and gets quite warm in operation; and of course, since spending months in a cold environment seemed temporarily to fix it.

posted by ArmyOfKittens to Computers & Internet (9 answers total)

Of course you should repeat this experiment to be sure, so take it out and let it chill again, or put it in a plastic bag and in the fridge overnight, and if it starts up for a bit, then you're good.

It is a common thing for electronics to fail due to heat. Basically, you have lots of little components soldered to a board with little metal blobs. These metal blobs rigidly secure the components... but the components are made of stuff that flexes just a little bit with heat. Eventually, this flexing breaks the solder, and ruins the circuit. The military used to encapsulate their electronics in epoxy for this reason-- telcos used pitch. XBOX owners have figured out that they can sometimes re-melt broken solder using just a towel; Apple owners did it with tea-candles.

In your case, though, it seems a less unlikely that it's a small component coming free from the board. I say this because the power supply is turning off, that's a bit worrying, as mentioned in the previous thread. That usually indicates that some power-related metal piece is touching some other power-related metal piece in an inappropriate way -- it sounds like a connection rather than a disconnection.

But the heat-theory still holds. Probably there is a piece of metal (most LCD interiors are shrouded in thin metal) which is touching somewhere it shouldn't, probably right around the power connector itself. When it's cold, this metal piece is say half a millimeter in one direction... and after the monitor heats up it's half a millimeter in the other, causing the short.

Before you take it into repair, you should really consider simply taking the monitor apart yourself, and then putting it back together. It's actually a relatively easy thing to do, it's informative, and chances are very good that you will "accidentally" fix the problem by repositioning the (mysterious) offending metal piece in the process.

I know it might sound a bit intimidating, but all you need is a screwdriver and a pliers, and LCDs, when unplugged, are some of the safest electronics to work on because the power supply is external.
posted by fake at 3:28 AM on December 5, 2009 [1 favorite]

Hang on-- the previous answer seems to have assumed that you tried several different power bricks, but it sounds like you only tried several different power cables (which are very simple and unlikely to fail anyway). If this is the case, I would replace the power brick (I have had to do that with one LCD monitor I've owned).
posted by alexei at 3:34 AM on December 5, 2009 [1 favorite]

Also, check some other power bricks you've got around the house-- you might find one with the same voltage, same-or-greater current, and same connector, in which case you can use it at least to test.
posted by alexei at 3:36 AM on December 5, 2009

Not all LCD monitors have external bricks. I have three that are internal: the cable from monitor to wall is just a fifty-cent 3-prong AC cable.
posted by rokusan at 6:34 AM on December 5, 2009

Yeah, I would definitely see if you can find another brick. It definitely sounds more like a brick problem, that's what the little light is for, right? Unless there is an electrical short inside of the monitor itself
posted by delmoi at 7:16 AM on December 5, 2009

I had a problem with a power adapter where there was a break in the cable very near the transformer. It would sometimes work for a bit, and then die if there was anything moved nearby. In my case, the fraying cable resulted in a short in the 'brick part', so the light would just go off.
posted by a womble is an active kind of sloth at 7:37 AM on December 5, 2009

Response by poster: Thanks, those are great ideas.

I've failed to scrounge up another power brick, but I'll have a more determined rummage through the Box of Old Technology and see what I can turn up.
posted by ArmyOfKittens at 11:19 AM on December 5, 2009

Leave it unplugged for a while before you open the case. They can store voltage a long time and bite you.
posted by unrepentanthippie at 7:43 PM on December 6, 2009

Response by poster: Yeah, the power brick scrounge has had no success, so I've moved it back into the bedroom for a while to calm down before I go at it with the screwdriver :)
posted by ArmyOfKittens at 4:59 AM on December 7, 2009