Lynx 2 Stereo Sound - Left channel varying volume

[Innervision180]

Hi all,

 

I am working on repairing a model 2 Lynx that wouldn’t power on. I replaced the voltage regulator components and brought it back to life. I also replaced the caps and the crystal oscillator while I was cleaning it up. I figured it was worth doing this to keep it running for a nice long while. Everything is running very well (even the screen, which I had no idea if it worked and thankfully had no issues). The only exception is an odd issue with stereo audio. 
 

The left stereo channel volume varies in loudness whenever that channel is triggered. I am using the stereo audio test on the Lynx 2 hardware test cart, so I am able to trigger each channel individually. The right channel is steady and loud without fail. The left channel is a random volume every time you trigger it, but stays steady at that volune while active. The left channel changing volume is noticeable when you activate and release both channels together as well. It’s noticeable during stereo games like Klax. The issue occurs on both the speaker and the headphone jack, so I don’t think it’s a defective speaker. 
 

I already replaced the 220uf cap, so that shouldn’t be an issue. I also reflowed the LM386 chip and L5 coil, but I haven’t outright replaced them as I don’t have real spares. I have a few working Lynx 2’s I could pull from to test if I really have to. 
 

Has anyone run into anything similar? Any suggestions would be really appreciated! Thank you!
 

 

[+karri]

I had a corroded pcb where the signal or the ground was floating. The cure was to solder a wire.