A31p high pitched noise when lowering screen brightness

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kosse · #1 Post by **kosse** » Fri Apr 18, 2008 2:38 pm

Hello everyone,

I got my new used A31p but there seems to be a problem: the laptop starts to make really loud noise when I lower screen brightness from keyboard controls even one step below full brightness. At full brightness it is, nonetheless, totally silent. The noise also starts if I try to use the laptop with battery power since the brightness is lower by default.

The laptop itself is pretty close to mint without practically any signs of use so it does not look like someone would have manhandled it in the past. The screen is also in my opinion quite bright and good for a laptop of this age. Where could the problem be? Inverter?

This is pretty annoying problem so any input would be appreciated.

Thanks in advance
kosse

edit:

Conclusion: The problem was fixed by changing a new inverter.

ajkula66 · #2 Post by **ajkula66** » Fri Apr 18, 2008 3:23 pm

My guess would be an inverter...

You can go into BIOS and change the brightness settings which will eliminate the need to adjust the brightness manually.

kosse · #3 Post by **kosse** » Fri Apr 18, 2008 3:31 pm

thanks for the tip. I tried BIOS settings but the problem still bugs me so much that looks like I'll be going inverter hunting soon. I guess I'll try the marketplace..

kosse · #4 Post by **kosse** » Sun Apr 20, 2008 11:45 am

Allright, I've been on a lookout for a new inverter for a while now but so far I've had no luck except running to a few broken A31's. Does anyone have first-hand knowledge can I use a A31 inverter in a A31p or are they LCD/GPU specific?

ajkula66 · #5 Post by **ajkula66** » Sun Apr 20, 2008 2:35 pm

They are LCD specific, meaning you need one that goes with UXGA panel.

Part number can be found in HMM, I believe.

sjthinkpader · #6 Post by **sjthinkpader** » Sun Apr 20, 2008 3:06 pm

The IPS panels use one type and non-IPS use the other type of inverter. I have mostly IPS panels in my A31/A31p now and used both inverters on IPS panels. The non-IPS inverters may yield lower brightness.

kosse · #7 Post by **kosse** » Mon Apr 21, 2008 6:10 am

Thanks for the input guys. I just found and bought a genuine new A31p UXGA inverter card. I will report back about the results when I get it and have time to install it to the laptop.

kosse · #8 Post by **kosse** » Thu Apr 24, 2008 7:13 am

sjthinkpader wrote:The IPS panels use one type and non-IPS use the other type of inverter. I have mostly IPS panels in my A31/A31p now and used both inverters on IPS panels. The non-IPS inverters may yield lower brightness.

So non-IPS inverter should most likely work OK in A31p? Because I just received one THAT WAS SUPPOSED TO BE for A31p but FRU (91P7737) says that is's for A30/31. I'm not sure if I should complain or if I'll just try this in my A31p.

kosse · #9 Post by **kosse** » Sat May 10, 2008 5:42 am

Allright, I had time to swap the inverters today. To my surprise my A31p had inverter part number 91P7737 inside it so I had received the right part after all!

Result of the operation: The noise has disappeared and the screen brightness is as good as it used to be.

Again thanks everyone for your help!

beeblebrox · #10 Post by **beeblebrox** » Thu May 15, 2008 2:26 pm

kosse wrote:Allright, I had time to swap the inverters today. To my surprise my A31p had inverter part number 91P7737 inside it so I had received the right part after all!

Result of the operation: The noise has disappeared and the screen brightness is as good as it used to be.

Again thanks everyone for your help!

You also just could have put a drop of glue on the piezo crystal to remove the noise. Your inverter is fine, it is simply the piezo-electric surface comb chip that generates that sound. After a few years it might get a bit loose and get into harmonic frequencies that makes it hearible to humans. Nothing to worry about, a drop of glue is just fine.

jadzia · #11 Post by **jadzia** » Wed Jun 18, 2008 1:49 am

@kosse or beeblebrox

I have also this sound - can you please describe me where exactly to put this glue stick on? ;o) - and how to get to the place?
Thnx,
jadzia

A31p high pitched noise when lowering screen brightness

A31p high pitched noise when lowering screen brightness

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