Older Dell laptop mic in jack goes dead after 10 min

[allsavy]

In using my cheap laptop to run guitar amp sim software out to a sml.guitar amp.
1/4 guitar patch cord is reduced to the required 1/8" input of the soundcard. Well after 10 min of operation the sound fades to nothing quickly. I have to then unplug and re-insert the 1/8" jack to get sound happening and again it fades within minutes.

Dying componect on the sound io ?

Terminals pullind loose ? (I am using light weight connection wires)

Anyway I have a spare old similar laptop to salvage a sound unit (I say unit because it is internal sml circuit bd) Just hesitating before diving in and replacing it. It is from the previous laptop model similar but different win drivers.

[Alex R]

Maybe it's some kind of power save mode.

[Steve Conner]

Laptop mic jacks usually have 3 volt phantom power on them. Maybe you're shorting it out and that does something funny. Try a DC block capacitor.

[J M Fahey]

Agree and add: plug an empty stereo miniplug there, measure if you have some voltage in tip or ring (now don't remember which does) and insulate that terminal.
Use the other two.
I also suggest you pad the signal you send there by at least 10:1, that's to say 22K from guitar ->1K across mic in.
That input expects a very feeble mic signal.
Probably it has some kind of AGC padding it down all time, needlessly.
Better you pad it yourself, in a predictable way.
Also try increasing the series 22K to 47K or 100K, if possible, to improve the guitar loading.
Or make some kind of FET or OpAmp buffer, that mic input is not exactly the best for guitar.
Good luck.
PS: did you say you would pull the soundboard components from a notebook motherboard and install it into another?
That sounds like neurosurgery to me. Congratulations on your guts.

[Gibsonman63]

Little two channel mixers are very cheap these days. For $29, you can get a basic mixer that will let you control the level going to the computer, plus the connection from the mixer to the laptop is not as likely to be disturbed while you are playing. If you want to get really fancy, you can buy a USB mixer with an input set up for and instrument level signal.