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freewheel

TIA replacement - any caveats?

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So in all of the dozens of 2600 units I've repaired and sold off over the years, I've never actually encountered this. Well, I finally got hold of a Vader that refused to output any video/audio at all. At first I thought the RF circuitry might be amiss, and I might be modding this one just to make it useful (this wouldn't be the first time, and there was a LOT of rust in this puppy). After getting no audio from the board itself with E.T. - easiest thing to check for that I can think of - on a hunch I decided to see if it was an entirely faulty TIA. Fortunately it was an early rev board so it was socketed, and coincidentally I've had a light sixer mainboard sitting in a junk drawer for a decade or more (can't remember what was wrong with it). A quick swap later, and success! Pretty cool to be able to do chip swaps like this, with everything else being surface mount and/or de-soldering 80 pins these days.

 

I'm curious if there are any known problems doing this. There seem to be quite a lot of TIA variants and they're not all exactly the same:

 

http://www.digitpress.com/faq/vcs_tia/vcs_tia.htm

 

Just wondering if anyone with more experience with TIA swaps has any words of advice, or if this is just as dead-simple as it felt like.

Edited by freeweed

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They've covered most of the bases by the look of it... doesn't mention though if the clone used in Coleco Gemini is pin compatible (no reason why it'd need to be aside from if they wanted to become an alternate spares source).

 

Also note PAL/NTSC are somewhat different, PAL loses the extra audio out and gains the colour clocking input among other things.

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Someone that modded a Coleco Gemini found out that its TIA chip pin out is different.

Atari Gemini

2 5

5 6

6 8

7 4

8 7

9 9

12 27

13 28

 

All the Atari TIAs should be swappable. Only thing I have found is an early gray TIA had glitches with modern cart hardware. It still works but Playfield pixels would blink.

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Oh wow, thanks! Oddly enough I was poking around 2600 Connection earlier that same day, just never found this FAQ. It was probably staring me in the face all along.

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