Re: Audio problems on VIC-20

From: Ethan Dicks <>
Date: Wed, 5 Jul 2017 15:09:32 -0400
Message-ID: <>
On Wed, Jul 5, 2017 at 2:23 PM, Francesco Messineo
<> wrote:
> On Wed, Jul 5, 2017 at 8:03 PM, Ethan Dicks <> wrote:
>> Hi, All,
>> I set up a retro-gaming event ...  couple of VIC-20s
>> ...the sound cut in and out...
> The audio signal is buffered with a single transistor
> emitter-follower, so you would first check
> it (solder joints and the 1uF electrolytic decoupling the DC after the
> emitter-follower).

Perfect.  Thanks for the info.

>> Another symptom is the colors weren't quite as "bold" as they were on
>> the working VIC-20...
> Inside the VIC metal box there's a 10k potentiometer that sets the
> video signal level. Again, this signal is then buffered by another
> emitter-follower. A DC-blocking electrolytic is placed before the base
> input to the emitter follower, so this one might also be dried out and
> have high  ESR.
> Your best friend is an oscilloscope in both cases.

Awesome advice.  I'll keep your words in mind as I check the
schematics.  Thanks!


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Received on 2017-07-05 20:00:03

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