Acer AL2017

[Undead]

This was the first monitor I tried to repair after I had purchased a replacement.
It originally would emit a high-pitched whine and then would turn off. After turning it back on and having the same thing happen several times, it would eventually stay on but would still have the whine.

I replaced the caps and there were no more problems with it staying on, however, the whine is still there. I think the noise is coming from the second transformer. I checked all the new caps last night now that I finally have an ESR meter and they all seem to be good.


(on an unrelated topic, I have always marked with colored pens to make sure the lamp plugs always go back into the same slot they came out of. Is this necessary or does it not make a difference which one they plug into? Assuming the wire reaches of course.)

[lcdman]

Re: Acer AL2017

Hello Undead,

Did you replace the cap by the opto-isolaters? It doesn't look like its been replaced. If so that might be the issue.

Take Care,
lcdman

[Undead]

Re: Acer AL2017

You are correct, it wasn't replaced as it didn't come in the kit that I originally purchased. I did replace it just now after your suggestion though and it didn't make any difference.

(now I always replace all of them except the big 400-450v ones)

[Undead]

Re: Acer AL2017

Wow almost 3 months with no other suggestions? I seem to be having a string of bad luck where nobody is familiar with any of the problems I'm seeing lol

adding 3 better quality pics just in case someone has an epiphany and needs a better look

[Undead]

Re: Acer AL2017

I think I am seeing something not quite right with U202 (just the appearance in the lower left corner of it that I can see in the new pic). How can I test it?

The markings on those chips are:

P605
BD6F2Y

I have also re-soldered all of the connections on the whining transformer. No change.

[budm]

Re: Acer AL2017

So did you swap the inverter transformer to see if it still buzz from the same location or it moved with the transformer.

[Undead]

Re: Acer AL2017

No I haven't tried that. Will give it a try right now.

Just swapped them and it sounds like the buzz is coming from the same spot, the lower transformer. I also noticed a buzzing in the upper left of the monitor where the wires lead to the lamps. Could the transformer issue be causing the lamps to buzz? I did switch the power board with another one for testing and there was no buzzing.

[ben7]

Re: Acer AL2017

No I haven't tried that. Will give it a try right now.

Just swapped them and it sounds like the buzz is coming from the same spot, the lower transformer. I also noticed a buzzing in the upper left of the monitor where the wires lead to the lamps. Could the transformer issue be causing the lamps to buzz? I did switch the power board with another one for testing and there was no buzzing.

Try replacing the big CapXon capacitor. If that has gone dry inside, then there would be excess ripple from the mains frequency. That could be causing the buzzing.

[Undead]

Re: Acer AL2017

The big CapXon only has an ESR of .49 so would that mean it has not dried out? It seems to be in the same range as the large caps in other boards I have out right now. Or can the ESR be normal but the cap still have excess ripple?

[ben7]

Re: Acer AL2017

The big CapXon only has an ESR of .49 so would that mean it has not dried out? It seems to be in the same range as the large caps in other boards I have out right now. Or can the ESR be normal but the cap still have excess ripple?

It could have low capacitance.

[Undead]

Re: Acer AL2017

Finally found one to swap it out for but it didn't make any difference.

[budm]

Re: Acer AL2017

Does the buzz change with the level of the brightness?

[ben7]

Re: Acer AL2017

Interesting. Well, one of the resonator caps could be bad. Does it smell? It could be a problem with the invertor control chip too.

Edit: Seems it doesn't have resonator caps. oh well.
Could it be that one of the high voltage blue capacitors is arcing inside? that is very likely.

[Undead]

Re: Acer AL2017

Ok I just tried the brightness, it seems to get slightly louder as the brightness gets higher, then as I keep going higher the sound kind of "warbles" and when it reaches 100% brightness the buzzing stops. When I start to lower the brightness the buzzing starts again.

I have not noticed any smell at all.

[Undead]

Re: Acer AL2017

Played a bit more, at 94% brightness it buzzes, 95% and higher it stops. Drop back down to 94% and the buzz starts again.

[budm]

Re: Acer AL2017

That is just like the HP monitors I repair, ending up replacing the lamps, it was strange since the lamps has no sign of worn out, no blackened ends. If I were you, just use it at full brightness until the lamps go out. Must be something with the PWM design that is not stable at short pulse width.

[Undead]

Re: Acer AL2017

Could it be that one of the high voltage blue capacitors is arcing inside? that is very likely.

Is there a way to test those?

That is just like the HP monitors I repair, ending up replacing the lamps, it was strange since the lamps has no sign of worn out, no blackened ends. If I were you, just use it at full brightness until the lamps go out. Must be something with the PWM design that is not stable at short pulse width.

Yes it is strange, it never made the noise before the caps went bad and my wife's doesn't whine at all. (I replaced all of her caps while I had it apart to swap the boards to test mine)