Using a VIC with a real Commodore monitor?

[Schema]

Since I'm doing more with my VIC than my 64 these days, I went to swap the VIC in place of the 64 at my desk, where I have a CM-141 monitor (1802 clone that matches the Plus/4)

The video looked awful! The white background was a very dark grey, but still with the cyan border and blue lettering. In fact, it went black if I turned the brightness down a tiny bit.

I get the same results with a good old 1702 monitor. Both of these monitors work fine with a C64, and the VIC output looks great on my TV (direct video input) with the same cable.

I *did* switch the monitors to the front (single video) inputs.

The VIC reference guide shows two different signals out - "Video High" and "Video Low". My cable has all 4 outputs on it - vidhi/vidlow/audio/+5V. I tried both videos, no difference.

What's the correct way of hooking this up, or is it even possible?

I can get passable video by cranking up the brightness and contrast, but I'm sure that's not the way it's supposed to be done.

[carlsson]

I also have to crank up contrast and to lesser extent brightness to get a good picture. Maybe it is due to how the monitor handles the composite video input. When I used to have a 1802 (the Tall variety with three inputs, as per Bo Zimmermann's description), I got a very nice VIC-20 picture. The 1084, as long as it worked well, gave a good, but not as good picture.

[vic user]

I have used a 1701 with one of my vic's for ages, and i get a fantastic signal. i have never had any problems whatsoever.

i have the brightness and contrast settings right in the middle of the range.

i do find that when i use the 40 column card with the monitor, i have to lower the brightness quite a bit, to get rid of the background haze of white, so all i will have is the white text on a solid black background.

hope you get a signal you are content with.

chris

[Leeeeee]

Both of these monitors work fine with a C64, and the VIC output looks great on my TV (direct video input) with the same cable.

...

I can get passable video by cranking up the brightness and contrast, but I'm sure that's not the way it's supposed to be done.

Actually it probably is. As your Vic works with the TV it's unlikely that there's too much wrong with the Vic output. The C64 video output is probably over driving the monitors, I'm sure I recall having to attenuate a C64 video output to get it down to a reasonable level for feeding a genlock a while back.

As long as you're not having to endstop the controls on the monitors I wouldn't worry, even then I wouldn't worry much. 8^)=

Lee.

[6502dude]

I have a few Vic-20s and there seems to be a bit of variability of brightness levels between them.

I usually just adjust brightness and contrast controls on the monitor for the Vic-20 that I currently have connected.

[Centallica]

Does anybody have problems with cartridges and a monitor (I've got a 1902 Commodore Monitor) that the picture goes to the extreme right on some games or part of the top is cut off on the pictures.

Strange when the start up screen is centred before putting the cart in. Some games that aren't as drastic can be adjusted by the adjustment knobs on the monitor but some you can't

Anybody have the same problem and any suggestions to correct this?

Mucho grandes,
Brian

[vic user]

i don't have that problem, but i have hardly any cartridges so maybe that's why i have not had that problem

chris

[Schema]

As long as you're not having to endstop the controls on the monitors I wouldn't worry, even then I wouldn't worry much. 8^)=

I am cranking them right to the extremes. It's not a big deal I guess, but it's a pain when trying to switch the monitor between the VIC and 64.

[Mikam73]

By the way.. Why there is Video high and Video low? I think high should be used?

[carlsson]

Does anybody have problems with cartridges and a monitor (I've got a 1902 Commodore Monitor) that the picture goes to the extreme right on some games or part of the top is cut off on the pictures.

Uh, isn't it a PAL cartridge you are using in that case? The values used to position screen are in completely different ranges on PAL and NTSC machines, so a game hard coded for PAL will appear far to the lower right on your computer, while for us in Europe, games will appear far to the upper left. Some games would allow the user to reposition the screen, but far from all.

I still don't see the technical reason why Commodore chose this anomaly. Maybe due to PAL will have fewer cycles per row, they had to make the border wider (smaller relative screen), and more room for screen movement. I assume the 6560 chip was developed and measured first, so they knew what was the median values and then had to re-measure things again for the PAL 6561 version. It would have been nicer if both chips would position the screen in the same ranges, but every 2nd value on the NTSC version would not make a difference.

[Schema]

What I forgot to mention when I first posted this (as I didn't think it was important) is that I was running my VIC through my VCR. This allowed me to use the VCR as a video switch to switch between TV/VIC/DVD player.

Yesterday I bought one of these 6-way video switches, so the VIC connects directly to the TV (through the switch). The VIC video looked dull and gray, just like on the Commodore monitors.

The output from my 64DTV and DVD player was similarly less bright than before (thought not as obvious as with the VIC).

So it looks like the VCR was boosting/cleaning up the signal to the TV. I need to try it on one of my monitors to say for sure.

I ended up putting my VCR between the video switch and the TV to give the selected signal a final 'boost'. Not as tidy a setup as I had hoped for, but it's easier than before.

[6502dude]

The new switch box may be degrading your video vs a direct connect.

Often low end switchers have poor isolation between inputs.

Poor shielding leads to RF interfence, crosstalk between inputs, and signal ingress from external sources.

The poorest quaility video switches are simple electro-mechanical switches. Often these units leave unselected inputs unterminated (causing video noise issues)

[Schema]

I just tried it again.

VIC directly to TV -> Greyish picture.
VIC through switchbox to TV -> Even darker picture.
VIC through VCR Video Input to TV -> Excellent picture.
VIC through switchbox to VCR Video Input to TV -> Excellent picture.

I got exactly the same results with my 1702 monitor.

You're right, this video switch is pretty cheap. But having the VCR there really cleans up the VIC picture.

[Leeeeee]

All video recorders have Automatic Gain Control on the active video signal. I use an old Sony that has four inputs just for this and the remote control switching.

What I forgot to mention when I first posted this (as I didn't think it was important) is that I was running my VIC through my VCR.

Something to remember for everyone I think, everything that is being used could be important.

Lee.

[Schema]

I asked about this again in comp.sys.cbm and got the following reply:

On 2005-12-27, Leif Bloomquist <spam@127.0.0.116> wrote:
> Both of my VIC20s put out what seems to be a rather 'weak' video signal:
> The screen background, normally white, is a dull grey.

You can adjust the video level from a potentiometer inside the
"video cage". There may be several potentiometers there, so pick
one, mark the original position, then adjust to see what it does.

-Pasi

Does anyone know more about this, and which potentiometer it might be?