Re: VIC 20 without audio tone

From: Francesco Messineo <francesco.messineo_at_gmail.com>
Date: Sun, 6 Jan 2019 17:10:36 +0100
Message-ID: <CAESs-_whcJ5cxU9HmXiTOW3P0bJwR70gGe61e34xfJxC8=BzJw@mail.gmail.com>
On Sun, Jan 6, 2019 at 5:03 PM fabry891 <fabrizio.vita80@gmail.com> wrote:
>
> Hi,
> thanks MiaM for your replay.
> I've checked the 6561-101 and there isn't any oxidation, as well as other
> parts of mainboard, nothing oxidation.
> The power supply that I use is the same for the C64, I checked the ouput and
> there is a surprise, 5.22 Volt DC between ground and pin 5, but 1.1 max 2.5V
> AC between pin6 vs gnd and 8.7V AC V between pin7 vs gnd, it's very strange.
> The frequence is correct 50 hz.
> This issue on pin 6 can be the cause of my audio?

9VAC can be measured only between the two AC pins, that supply is just
a floating (i.e. not connected to ground) transformer secondary.

> I replace the fuse and I saw a strange white material, like oxidaton into
> the fuse holder.
> If I want to replace the 6561-101, I simply buy a new one and insert into
> the socket, or it need to be programmed?

6561 are very expensive and by the way, are you only trying via a RF
modulator to a TV? RF modulators easily go out of tune and can produce
a way off sound carrier or transmit out of frequency between two
channels too. Your TV might be trying to autotune (and might also fail
at correctly auto-tune) or might even not try to tune to the correct
channel.
You can't conclude anything without trying how the audio sound
directly at the A/V connector.

PS: 6561 don't need to be programmed.

Frank
Received on 2019-01-06 18:00:30

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