Re: A session with my VIC-20

From: William Levak (wlevak_at_cyberspace.org)
Date: 1999-08-21 05:17:31

On Fri, 20 Aug 1999, Carlsson, Anders wrote:

> Hi, all.
> 
> Yesterday evening, I decided to pull out my VIC-20 from the pedestal,
> to check a few things I had forgotten with it. This is a session log:
> 
> 1. My 1084S monitor (which I use with the Amiga) has trouble with
>    vertical sync (I think it is called - the picture is scrolling
>    from top to bottom) on CVBS signal when the border colour is light.
>    I.e. the startup cyan/white combination will scroll and colour
>    is gone, but if I do "POKE36879,24" to get black/white, the screen
>    is stable and colours re-appear.
> 
>    I opened the monitor to see if there is some knob I could adjust,
>    but found none. I had this monitor on service previously, as it
>    didn't work at all. Before I had that breakdown, CVBS signal was
>    OK.

My service information shows a video level adjustment on the video output
from the VIC chip.  You may be overdriving the monitor.
 
> 2. My 3/16/24/32K expansion card seems to finally have died. I tried
>    to clean the weared connectors, but without success. What can one
>    do to bring it back to life again, if it only is the connector
>    pins that are damaged? Otherwise, I'd have to build my own card
>    as there is a description on the net.

There are several versions of these cards. You will have to do a little
experimenting.  You should not have to build a new card, only replace some
chips.  If your card has driver chips or logic decoders, check these
first.  A logic probe is usually necessary.  Check the bank select lines
and the most significant bits of the address lines.  That should tell you
which chips are working.


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