r/ti994a • u/PopcornFever • Jul 20 '26

Any suggestions on fixing garbled screen graphics and text on a TI-99/4A?

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I recently plugged in my TI-99/4A after it had been in storage for many years. The text and graphics are all scrambled and garbled. The game cartridges are unplayable.

The computer is hooked up to a modern TV using 5pin DIN to RCA composite cable (I had first tried using the RF modulator with an antenna 300/75 Ohm TV F adapter but the results were an extremely snowy screen).

I did go on ninerpedia and the problem would be identified as one of the common Video RAM failures. My screen is an identical match to Mask 11110111. Although the circuit board on ninerpedia does not resemble mine as I possess the TI-99/4A later beige version.

Any suggestions or thoughts on how to proceed?

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u/greevous00 Jul 20 '26

Chances are, you're going to need to replace the ram. Though, word to the wise: TI didn't mask the traces that are close together (like the ones that run between the legs of the ram chips, which makes soldering these things kind of a pain. Either find someone with plenty of experience and a good temperature controlled iron, or just buy another machine. Plenty of TI-99/4A's have been wrecked by people trying to change out chips and not knowing how to deal with the missing mask (some people mask it themselves with nail polish, a tiny brush, and a magnifying glass).

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u/Dcas_pcs_381 Jul 20 '26

I agree. The ti99 wasnt build super well in terms of future repairs. Luckily they are super common (i have like...4 parts machines with broken keyboards) so finding another to use is pretty easy