Thinkpads Forum

HI, does anybody know why my 770z's speakers are crackling and popping like a headphone jack that isn't plugged in all the way? I'm typing on it now, and when i unplug/plug in my charger, it still makes the classic "BeeBoop" noise, fine, nice and clear, but other than that it's making these weird crackling sounds for no apparent reason. I had this problem a while ago but only on startup, and this seems completely unprecedented. ANy help would be greatly Appreciated!


If it's any help, I'm running Windows 2000 server, No service packs according to system properties. The stats are in my sig.

Plug a pair of headphones into the output jack and see if the noise occurs there as well. If so, then you're probably looking at some leaky capacitors in the motherboard's audio circuit. If the noise is not in the headphones, then maybe the switching contact in the output jack is dirty. Or there could be some other intermittent contact being made somewhere inside the system. Doubtful that this is any software issue.

The cause of this noise can be that the third battery has started leaking.
As I recall it from when I had a leaking battery in a 770, one of the components that was damaged was the volume pot.

I am not sure how it is in a 770, but usually in ThinkPads, the audio circuitry has a DC/DC converter of its own.
This to prevent any noise from the supply voltage to reach the audio amplifier. So that is another error posibility.

To analyze the problem further, you might connect an audio cable from the 770's line-out to the line-in jack on another computer
and then record the noise. Afterwards the recorded audio file can be opened in a wave-editor and analyzed, to answer questions like:
Does the noise occur on both channels?
Is it something that occurs breiefly at regular intervals?

I will recommend that you start by inspecting that third battery. To get to it, all you have to do is to remove the keyboard.

I don't know how simmilar this is, but I have had 2 laptops of simmilar vintage with that problem. On one the problem started suddenly and it seemed to be to the hard drive - you could hear the hard drive wining and the high pitched sound coming out the speakers. On the other one it was like that when I got it. If you have a quieter hard drive, try it to see if it solves most of the problem.

Good luck

Jack

Wow, thanks for all the responses! I didn't think I'd get that many that quick!

SMA, what do you mean by the third battery? The CMOS? Or it there some other battery that i know nothing about
I'm going to try my headphones as soon as i can get it to boot up (My CMOS battery is dead, so i have to set the clock at every startup)!

I'll try all of your ideas, and get back to the thread ASAP!

Thanks again!

A little unusual these days, but in a ThinkPad 770 there are 3 batteries.
The main battery, the cmos battery and then the backup battery.
So, unless the third battery has already been removed, then the answer is yes, there is a battery in there that you do not know of.

We have been discussing it in this topic http://forum.thinkpads.com/viewtopic.php?f=6&t=53903

Oh, Cool!
Thanks, SMA, I'll check that out!