Cosmic Ark sky color

[fluxit]

Having recently reaquired my childhood '2600' model, the Coleco Gemini, I gave the purchased filthy beast a refurb. 

 

Every surface, inside and out needed a scrub.  Some made do with a soft cloth, others needed a moist cloth or even bit of IPA here and there.

 

The aluminum handled switches were all fouled.  I blew them out with air, dripped a few drops of IPA into each switch with the switches in both positions.  Then I exercised each switch 12 times and blew out the remaining IPA.  This was followed with a couple of drops of deoxit cleaner(red) per switch.  I made new cover slides, and the switches are 100% working.

 

The cart slot contacts were clean, but a bit loose, so I tightened them up a bit with a bent pin.

 

The board was largely pristine, other than a somewhat ugly power jack repair or replacement, and a fine but ugly port 1 repair.  I redid those two.

 

At this point, the Gemini was working great, except for the colors, which were *way* off.  In Super Breakout, for example: yellows were very greenish, most other colors were either shades of violet, or gray, lots of gray.

 

The color pot had been turned all the way to the right(IIRC.)  I swear it wasn't me.😁  I didn't even need to clean that part of the board.

 

I reset the pot to center, and slowly adjusted(anti-clockwise?) until yellows were no longer greenish.  Having done this, most games displayed relatively properly, except for Pitfall!, which I guess is supposed to have a tannish ground and brown underground(instead both are green,) and Cosmic Ark, which has a light greenish planetary sky, instead of blue.  I could not achieve tan ground in Pitfall! with the Gemini's color pot, only by adjusting my crt's tint to '-14' did the colors all look correct. 

 

Adjusting the tint did not negatively affect the games that already were close to correct.  However, in spite of the fact that my tint adjustment reduced the green in proper greens and yellows, it had no apparent affect on Cosmic Ark's light green sky.

 

I can get proper Cosmic Ark sky color by adjusting my tint to '+12.'  Of course this blows Pitfall! *way* into the greens, and reduces some other yellows to shades of green as well.

 

Any ideas?  Again, with my current Gemini color pot setting, and my crt's tint on '-14,' other than Cosmic Ark's strange minty green sky, all other games I've tried so far(8) have bright appropriate colors and smooth color gradients(where applicable.)