8 Sep
1998
8 Sep
'98
4:43 a.m.
On 7 Sep 98 at 19:14, Tony Duell wrote:
I just checked my old VIC20 Programmers manual from C= and
VIC20 manual both showing the pinouts. They call the pin 4 video low
and pin 5 video hi. The pin 1 +5v has a note 10mA max. Is it possible the
difference between the video pins was the hi-lo tuning on older TVs
(CH 2-7 .8-13 ?). That would explain why there were 2 plugs
on the RF modulator box output. A C64 plug with the 4 (or 2) line split-out
would give him the composite and audio signals needed.
The Programmers manual is a great little book, C= also included the
schematics with it. I see that Q1 output is tied to both pin 4 and directly
to pin 5 but with the pin 4 fed thru R8 a 47ohm r and with another line thru a
75 ohm R8 to ground. The schematic also marks the 1pin as 6v . Why the
discrepancy between the +5v pin 1 p-o diagrams in both of my C+ books and the
schematic and your tech manuals' +6v ?
ciao larry
lwalker(a)interlog.com
It's been
a while and my VICs are buried under a pile of other stuff but I
think the problem is that the box is a RF modulator that has to go directly
into your TV to split the signal into audio and video. I don't remember there
Wait a second....
According to the Tech manual, the output from the VIC20 is composite
video and line level audio. There was an external RF modulator that
plugged into that socket and connected via a switchbox to the aerial
socket on a TV, but if you TV has composite video inputs, etc, then
there's no need to use a modulator.
It sounds like that's what the original poster was doing. The fact that
they got perfect video implies that _something_ was right - mix up RF and
composite video signals and you won't get anything.
-tony