Two TI-99/4A Systems, two problems

TI-99/4A Hardware problems, questions, etc.

Two TI-99/4A Systems, two problems

Postby malakai » February 3rd, 2011, 2:43 pm

One of my systems works but shows garbled video, various ascii characters, etc. The other just goes straight to a black screen. It was making a noise but now it doesn't even do that. I just ordered a cf7+ and planned to use it on one of the ti systems, but it's looking like I may have to go buy another one.

Any way to possibly make one TI-99/4a out of the two systems?
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Joined: February 3rd, 2011, 2:39 pm

Re: Two TI-99/4A Systems, two problems

Postby Ben Yates » February 10th, 2011, 7:08 am

You might try pulling the GROMs out of the 'black screen' computer and putting in your other one. I had an issue where in TI BASIC after some time a GROM would overheat and my character definitions started to go 'wacky'. TI BASIC/XB reload the character definitions at the start of each command line you enter, and I would see the characters change each time I'd enter a command line or a program line. But not while sitting there - if it happened when I didn't press enter, I'd suspect the VDP chip wasn't refreshing the DRAMS correctly, or a bad DRAM chip.
Ben Yates
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Joined: January 25th, 2011, 4:11 am

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