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copperboy

Does anybody here have Coleco Gemini?

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Does anybody here have Coleco Gemini?

 

I am doing some maintenance work on mine.

The original TV to Game switch thing seems to produce a very noisy picture. 80% of the dots are randomly white so I can’t see anything.

I tried with a NES switcher but it is still way too noisy.

I tried with a SEGA Genesis switcher but it is still way too noisy.

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Those type of switcher will always produce snow and grain with older systems of the Coleco Gemini era (ColecoVision, 2600 etc) as the signal does not fully support the auto switching built into those types. IF your original manual switch type is producing grain you should just try with a RF to coaxial adaptor, they bypass the need for the Game switch and connect the cord directly to TV input. Does the Coleco Gemini have a channel select switch on back? Make sure it is set to the same channel you are attemting to tune it to as well. 

 

Example RF TV Coaxial F Plug Female Adapter

https://www.amazon.com/RFAdapter-Connector-Convertor-Commodore-Colecovision/dp/B07VWQF6WS/ref=pd_lpo_1?pd_rd_i=B07VWQF6WS&psc=1

71aZYIkNEpL._AC_SX425_.jpg.fa807fd30ca6b55b046f1c6167e5229e.jpg

 

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6 hours ago, OldSchoolRetroGamer said:

Those type of switcher will always produce snow and grain with older systems of the Coleco Gemini era (ColecoVision, 2600 etc) as the signal does not fully support the auto switching built into those types. IF your original manual switch type is producing grain you should just try with a RF to coaxial adaptor, they bypass the need for the Game switch and connect the cord directly to TV input. Does the Coleco Gemini have a channel select switch on back? Make sure it is set to the same channel you are attemting to tune it to as well. 

 

Example RF TV Coaxial F Plug Female Adapter

https://www.amazon.com/RFAdapter-Connector-Convertor-Commodore-Colecovision/dp/B07VWQF6WS/ref=pd_lpo_1?pd_rd_i=B07VWQF6WS&psc=1

71aZYIkNEpL._AC_SX425_.jpg.fa807fd30ca6b55b046f1c6167e5229e.jpg

 

That is how I connect my Gemini also

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12 minutes ago, copperboy said:

Is that just a connection (just a conductor) or is there a resistor or a circuit inside?

Straight pass through 

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What cable are you using?  It should be RF shielded.  A regular AV cable will give you a noisy picture.

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16 hours ago, mr_me said:

What cable are you using?  It should be RF shielded.  A regular AV cable will give you a noisy picture.

I tried the original Coleco switch + AV cable since somehow I misplaced the original RF cable. I don't know what the internal of the AV cable is like.

I think the AV cable is 3 mm to 4 mm in thickness.

 

For the NES and Sega Genesis switcher thing, the RF cable is integrated. I think they are 3 mm diameter.

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Get yourself an RF Cable (preferably an old one as I have had varying degrees of success with new ones) and the RF-Coaxial Adapter.

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I would have to see if there is a better cable and that adapter at my thrift store or electronics store.

 

I did a temporary connection with a cable TV coax cable. The image looks pretty clean. Woohoo!

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11 hours ago, copperboy said:

I would have to see if there is a better cable and that adapter at my thrift store or electronics store.

 

I did a temporary connection with a cable TV coax cable. The image looks pretty clean. Woohoo!

I agree that using a thick coax cable with the RCA  adapter will provide a cleaner picture than using a RCA cable with the coax adapter

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My Gemini looked best with a cable-TV coax cable (very thick, hard to bend) and the RCA-to-F-type adapter linked above. If you do open it up, look for broken solder joints on the controller connectors - both of mine were bad, as was a crack developing on the joints for the DC jack.

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On 9/15/2021 at 2:36 PM, leaded solder said:

My Gemini looked best with a cable-TV coax cable (very thick, hard to bend) and the RCA-to-F-type adapter linked above. If you do open it up, look for broken solder joints on the controller connectors - both of mine were bad, as was a crack developing on the joints for the DC jack.

Yes, the controller port of controller 1 had a problem long ago when I had the Gemini for a few years (1985?). I think since we insert and remove the controller often, it flexes and develops a crack in the metal. This was fixed.

Port 2 is fine since I never used it.

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On 9/19/2021 at 12:17 PM, copperboy said:

Yes, the controller port of controller 1 had a problem long ago when I had the Gemini for a few years (1985?). I think since we insert and remove the controller often, it flexes and develops a crack in the metal. This was fixed.

Port 2 is fine since I never used it.

I needed to re flow both of my joystick ports also

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