>>>>> "NW" == Nicolas Welte <welte@chemie.uni-konstanz.de> writes:
NW> I wonder if it has something to do with the different output
NW> levels of the two video pins on different versions of the VIC-20.
NW> I think I found the old VIC-20 version to have dark white when I
NW> use the normal video cable from a 64 that takes video from pin 4.
NW> I ended up to adjust the video level with those internals pots to
NW> show a bright white, maybe bright grey, so I have good contrast in
NW> the picture. I'd really like to know what it really should look
NW> like ...
Hey, this is exactly the problem that I have -- and it's what's
keeping me from taping VVV and VIMM... If I use the 5-pin C64 video
cable I get a pretty sharp image, but colours are dark and washed out.
The white background is more like colour 15 or 12 on the VIC-II. If I
use the RF box I get a slightly brighter but much grainier image.
Raymond Carlsen said on comp.sys.cbm:
Ray> I've seen failing VIC chips in the C64 do that. The VIC chip in
Ray> the USA version of the VIC20 is UAB7, a 6560 (the PAL version may
Ray> use a different number). Before replacing the chip, I would check
Ray> or change Q1, an NPN transistor used as a buffer to the video
Ray> output. Any small signal NPN should work in that application.
And Nicolas Welte suggested:
NW> You could try to adjust the video signal level with the internal
NW> pots in the VIC20. They're near the VIC chip, there's one of them
NW> for the small VIC20CR board and two for the large original VIC20
NW> board. Don't touch the adjustable capacitor in the clock circuit
NW> that is very close to the other adjustments. Especially with a
NW> metal screwdriver it's not easy to adjust it.
Haven't had the time to try either, but it might be worth a shot. I
was about to buy a second VIC-20 to have something to compare with,
but the seller screwed up. Royally. Still a bit pissed off :/
--
___ . . . . . + . . o
_|___|_ + . + . + . . Per Olofsson, konstnär
o-o . . . o + MagerValp@cling.gu.se
- + + . http://www.cling.gu.se/~cl3polof/
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