Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

[mobotest]

Hello,

Monitor:
Acer S231HL LCD LED

Adapter:
Delta Electronics ADP-40PH 19V 2.1 AC/DC

Symptom:
No monitor power LED light. Monitor did not turn on.
Adapter measured 18.92V at adapter barrel connector.
Then after a month of leaving monitor unplugged, monitor started working again yesterday.
Adapter still measures 18.92V.

Questions:
1. Is 18.92V output within spec for a 19V adapter? or is it a sign of future failure?
2. Does the described behavior indicate some component in the monitor that is faulty or about to fail which will cause the problem to recur?


TIA

[zen]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

Hi

If you have another adaptor to test , i would eliminate that as the cause first , before stripping monitor .

Regards Zen

[lotas]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

Hello,

Monitor:
Acer S231HL LCD LED

Adapter:
Delta Electronics ADP-40PH 19V 2.1 AC/DC

Symptom:
No monitor power LED light. Monitor did not turn on.
Adapter measured 18.92V at adapter barrel connector.
Then after a month of leaving monitor unplugged, monitor started working again yesterday.
Adapter still measures 18.92V.

Questions:
1. Is 18.92V output within spec for a 19V adapter? or is it a sign of future failure?
2. Does the described behavior indicate some component in the monitor that is faulty or about to fail which will cause the problem to recur?


TIA

The power supply must be checked under load, without load it can give out 19v., And with load, the voltage may drop.

[mobotest]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

I do not plan to open the monitor since it is currently working. Because it did not work for a short period and there is a possibility the problem might happen again, what I'm wondering are:

Questions:
1. Is 18.92V output within spec for a 19V adapter? or is it a sign of future failure?
2. Does the described behavior indicate some component in the monitor that is faulty or about to fail which will cause the problem to recur?

[R_J]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

The voltage from the adaptor is fine, It's only .08 volts low. The main board is quite simple so it's hard to say where the fault is, it may just be a poor connection on the dc input jack. It could be that the main microprocessor data got corrupted and after sitting for a while it cured itself.

[mobotest]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

Monitor stays in one place. It isn't moved so I doubt the DC input jack connection was the issue.

If 18.92V on a 19V adapter is within spec, I suppose the adapter is not the issue.
So could failing capacitors in the monitor have caused the problem?

[momaka]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

Questions:
1. Is 18.92V output within spec for a 19V adapter? or is it a sign of future failure?

Voltage-wise, yes.
Most IT equipment power supplies typically have a tolerance of +/- 5% on their output voltages. So in the case of a 19V-rated adapter, anywhere from 18.05V to 19.95V is considered in-spec.

That said, the output voltage you measure doesn't necessarily mean the adapter is giving out "clean" power in spec. Just like the DC voltage level, the ripple/noise on the output also has an allowable tolerance. Ripple/noise is the amount of "dirty" voltage coming out of the adapter. It's typically only a few mV to a few 10's of mV... but even that can cause issues.

Unfortunately, you can't measure ripple/noise with just a multimeter. You need an oscilloscope for that and also you need to put the PSU under full load, as member lotas noted above.

Thus, we can't conclude with 100% certainty that your power adapter is OK, just based on the voltage it is outputting. Though in all likeliness, it probably is OK.

2. Does the described behavior indicate some component in the monitor that is faulty or about to fail which will cause the problem to recur?

I don't think anyone can say anything conclusive about that.

The problem is, your monitor's issue appeared only once and then went away. If there is a way to re-create it (i.e.: perhaps unplug the monitor for 1 hour and keep in a cool/cold place, then try turning it On after that), then we can try different things to see what causes the issue to disappear. And only then we may be able to tell what is more likely to be the issue.

So in short, with the information provided so far, it's not really possible to say what exactly caused the issue you had.

[mobotest]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

Appreciate all who provided input.

@momaka
Just to clarify, monitor stopped working while in use. Then it was unplugged and put aside because it stopped functioning. And started working again after replugging a month later.

I'm not clear on:
If there is a way to re-create it (i.e.: perhaps unplug the monitor for 1 hour and keep in a cool/cold place, then try turning it On after that), then we can try different things to see what causes the issue to disappear.

I suppose you're saying I'll have to just wait till the problem recurs.

[momaka]

Re: Acer S231HL LCD LED Monitor - No power then works after unplugged for a month

I'm not clear on:
If there is a way to re-create it (i.e.: perhaps unplug the monitor for 1 hour and keep in a cool/cold place, then try turning it On after that), then we can try different things to see what causes the issue to disappear.

I suppose you're saying I'll have to just wait till the problem recurs.

You can wait for the problem to happen again, sure... but you don't have to is what I'm saying. In particular, solder joints and bad caps tend to react to temperature changes. Thus, as I suggested above, you can try unplugging the monitor and placing it somewhere cool/cold for a few hours, then bring it back in and see if it will start normally as soon as you plug it in. Capacitors, especially, tend to get "lazy" in cool/cold temperature (their internal ESR increases), so if there are any marginal caps in your monitor, this "trick" might show you if that's the case or not - i.e. if the monitor fails to start after being kept in a cool/cold place for a few hours unplugged, then you can suspect bad caps somewhere. Or it could also be a bad solder joint. But in any case, changing the ambient temperature of the device is one way to trigger the problem sometimes, which can be helpful if you want to see whether there is one or whether whatever happened was just a "fluke" or one-off case (i.e. there was no problem, but maybe something random happened that you just can't explain that wasn't a fault of the monitor.)

So in short, if you want to "mess around" with the monitor to see if you can re-create the issue, you can. But if not, then you'll just have to wait until the issue happens again. Apart from those two (or opening the monitor and checking yourself - which you stated you don't want to do), there really isn't much else we can say about what happened the first time.