Looking for Help Fixing a Coleco Gemini

[earthad1]

Hi,

I've recently come across two Coleco Gemini consoles. I got one working no problem, but the second won't display any Picture. Powers on as my TV goes to a solid grey screen.

 

Known good power supply.

Known good game

Known good AV Chord.

 

Tested all the above with a working Gemini and it works very best, so the problem is isolated to the guts of this console.

 

I checked the power input and reinforced the solder on it. I checked the voltage regulator and it seems ok.

 

I've also re-flowed the solder to the cartridge slot and all the chips. I think the RF Modulator is bad but I'm not sure how to test it with my multimeter? I removed the shielding from it to get a good look inside and re-flowed all the joint to all the components but nothing has changed. Also, is there a way to confirm if a chip is bad with a multi-meter? 

I searched on here to find any threads with a similar issue and there's not much for this console. What I've dug out was some people mentioned that its made with off the shelf cheap parts and the solder is notorious for failing. So those are the issues I tackled first but still the same grey output on the screen.  

When I wiggle the channel select it does have a effect on the screen though. 

At this point my guess is bad chip(s) or bad RF Modulator. I guess it would make a good candidate for a Composite mod, but I've never done it before and not even sure if the kits for a 2600 would work on this thing. I've searched for anywhere that would sell parts for this thing (especially the chips) but that too seems pretty hard to come by.

 

I can provide photos if anyone wants to take a stab at it.

 

Any help would be greatly appreciated. 

Thank you.

[Geoff Oltmans]

Better to ask this question in the Atari 2600 subforum since that's a 2600 clone.