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ADAM - Video issues


344Clinton

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Greetings.



It has been quite a while since I have been on the mailing list and it seems very quiet there, so I'll repost here.



I have pulled my adam out of storage (yes, my lovely wife was away for the weekend!) and set it up.


Everything is still running but for a big few issue and a printer issue (separate post).



Occasionally, when I power the unit on, I will get sometimes get a partially garbled screen. Everthing works fine, but the screen has weird characters on it. If I reset, it's usually fine,but it may take a bit. The coleco side seems fine.



However, after work today, I turned on the adam and it was consistently pretty garbled. Now,the message "TURN GAME OFF" is ALWAYS garbled the same way. By comparing the hex values of what is displayed with what they should be, I believe bit2 of the vram is bad. These are the tms4116 ic`s. I read that bit 2 would actually be bit5 on the vram. Can anyone verify/debunk this? I have cleaned the power switches out last year, so I am pretty sure that is ok.



I have read that some people use newer 4164 or 4516 ic`s. Has any one used these in an adam?



Craig


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It's been done on the Colecovision and the board with the CPU, VDP and display RAM is basically the same circuit with a different layout.
There was a recent thread about the Colecovision mod and I looked at the schematics for the ADAM.
The mod should be the same, you just have to locate the parts on the different layout and where to jumper to.
*edit*
http://atariage.com/forums/topic/216710-can-a-colecovision-5v-memory-mod-be-done-on-a-revd-1983-motherboard/

Edited by JamesD
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  • 2 weeks later...

Well. I got my ram from console5.com who very prompt in shipping!

 

The original chips were quite difficult to remove as the pins were bent over in the pcb. I removed L2 and L3(-5v and +12v). And jumpered pin 9 to pin 8 on one of the IC's for the 5v.

 

Worked great!

 

I might order a second set of ram for a $10 memory expansion!

 

Craig

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