Commodore Monitor Color Curiosities

[intric8]

In March my C128's glorious 1902A monitor went black. My friends believe its flyback has bad solder joints, which is a fixable problem. But when it comes to monitors I get very nervous. So before trying to take it all apart and wonder if I'm "doing it right" I looked in my storage for a backup monitor to use in the meantime. After some brief research, I determined my 1084S monitor could work in both 40 and 80 column modes if I had the right cables. Which I didn't. Turns out these are not very common. (For 80 cols I needed a male/male RGB cable since now both the monitor and C128 have female ports.)

When I got back from a trip to Texas late last night, there was a small pile of things I’d ordered waiting for me on my dining table. In the pile was that very special cable, which came all the way from England. It took me several minutes to figure out how to enable 80-column mode (it’s not nearly as obvious as with the single-buttoned 1902A). But after a lot of trial and error, I finally got it to work.

The 1902A is classic, but the versatile 1084S looks so damned good with just about any machine - C64, 128 or Amiga.

Two interesting things about the 1084S that are quite different than the 1902A.

1) The color brilliance and brightness are much more subdued on the 1084S in 80-column mode. That really surprised me. (Of course it’s 40-col mode far outshines the 1902A - no contest). On a black screen in BASIC, some characters actually create bizarre, faint yet very long horizontal ghosting almost across the entire screen.

2) The colors are completely “off” with GEOS. When I saved my Gateway desktop color scheme during my original setup, the desktop was a deep navy blue. When I launched it today it was now deep red.

?!

Moving the color adjustment wheel on the front panel of the 1084S made no difference to what I saw on the screen. I wound up going into Gateway’s control panel prefs and picked a completely different color scheme.

So is the 1902A the “correct” color, or the 1084S? I'd bet my life that the 1902A is truly correct. I believe (know) the 1084S colors are wrong because when I launch Gateway/GEOS, the first weird static screen we always see on boot is red instead of gray. Not slightly red or pinkish, but true red. It’s super strange.

However, since GEOS is essentially a b/w experience I can find a preference that gets me there after the deskTop loads. In reality, I’m probably picking some very strange color combination, but under the current circumstances it looks mostly normal. And it is very crisp, which is important.

I wonder if the new 80-col cable I got has some wires crossed that makes the colors all wacky, even though the actual graphics look crisp and clean?

[Zippy Zapp]

Interesting. Hopefully you get the 1902 sorted. As to color differences that could very well be down to the calibration or tuning of the monitors.

[intric8]

Update

In the past few days, my 1084S also started to intermittently go black screen as well. However, interestingly, I could boot into 40 column mode. Only 80 columns was out.

In bit of a panic and lacking ideas, I swapped the cable's direction: I put the plug that had been in the computer into the monitor and vice versa. The monitor woke up, and suddenly the colors were accurate! That made no sense to me at all, but I continued on my current C128 project.

During the evening I needed to turn the machine on and off a few times. Sometimes 80 cols would come back, sometimes not. Then, finally, 80 cols went completely dark again. And yet 40 cols was OK!

So. I took the machine apart, removed the PSU and popped open the little tin that holds the VIC II and VDC.

Logic would dictate the VDC should be replaced as it is in charge of the RGB video. But I only had one single VIC II loose and ready to use. Thus, I replaced that chip instead and put everything back together.

To my total surprise the 1084S sprang back to life! "What the hell...?"
I ran and got my "dead" 1902A and swapped monitors.

Now, of course I'm going to let the 1902A run for an hour or two, turn it back off and on again, etc. before I declare victory. But at the present time I'm massively confused.

Why did swapping the direction of the cable make a difference with color on the 1084S? And why did swapping the VIC, instead of the VDC, make a difference with outputting 80 column mode?

I've ordered a spare VDC in the meantime...

[intric8]

I installed the "new" VDC tonight.

Now I wait...

If it lasts more than 2 hours, then the VDC is likely the source of the issue and not the monitor after all. That would be great news. I should know by tomorrow.

[intric8]

Welp, that didn't take long (unfortunately).

Ray Carlsen, here I come! Will be dropping off this lovely monitor this Friday for - hopefully - a repair that will last me several more years. My friends believe the results seem to suggest that there is a bad solder joint that would require a reflow of the joints where the flyback is soldered.

[intric8]

Ray Carlsen fixed the monitor this weekend. As some of my local friends hypothesized, some of the solder joints needed to be reflowed around the flyback. It's now 100% back in action and has returned to its proper place.

The dang thing definitely gave me new white hairs trying to figure out where the problem was coming from.

[McTrinsic]

Glad to hear it’s solved!
It makes me a little happy to see old tech being rescued