Lynx I - Distorted Sound Output - Audio Circuit or Mikey problem?

[spspspsp]

I have a Lynx I that recently developed sound problems. I play this Lynx relatively frequently, and the it happened all of a sudden.

 

Specifically, the sound is distorted and seems to be missing the high frequencies. 

 

I have attached a recording of this Lynx playing the opening from California Games, along with a clip of what it should should like.

 

Bad_ Sample.m4a

Good_Sample.m4a

 

This sound comes through the speaker and through the headphone.

 

My first thought was to recap the audio circuit--which I did today--and it didn't help. I replaced all electrolytics, including those under the shielding since that is where most audio circuitry is.

 

 

The audio circuit is above. Does this appear to a problem that could arise in this circuit, rather than a problem with Mikey?

[spspspsp]

I think I found the issue. I was probing the circuit, and found that there was distortion at the positive terminal of C8. This eliminated main part of the audio circuit.

 

I went back to L23 and L24. Looked fine, until I gently lifted them up. Then I saw it. Traces of blue-green corrosion. It must be affecting the signal path from Mikey. It looks fixable--but I'm surprised to find corrosion on that part of the MB. There aren't any electrolytic capacitors in this area, and it should have been protected by the RF shield from fluid, plus there isn't an easy path to or from the batteries.

 

It must have been there slowly spreading for ages, but only recently became bad enough to affect anything.

 

Corrosion is the worst--because once it's there it self-propagates.

[spspspsp]

Yep, that fixed it. I removed the corrosion with vinegar, cleaned it up, then found and fixed a broken trace between pin 10 of Mikey and L24.

 

Unfortunately, I can't be sure I removed 100% of the corrosion, but I'll make a note and try and keep it with this system.