Powering-up Apple 1 Replica for First Time

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RussellSpeight1967's picture
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Powering-up Apple 1 Replica for First Time
Hi Everyone,  I've recieved lots of help over the last 3 months from people on this forum while I collected the components and built my first Apple 1.  I've followed Mike Willegal's "Apple 1 Mimeo Computer Assembly and Bring Up Guide", and am now at the point if testing the Video Circuit.  I 'm based in Australia so shipping here can be expensive and slow.  After power up, I see characters scholling up, the the screen is blank becides the 20 x 24 dot matrix (I've read Mike's Hardware notes how to eliminate these, page 4/6).   I beleive I have made a Rookie mistake and purchased 74LS161AN ICs for D-7-D9, D11 and D15. I see now that D8 needs to be 74161, not 74161AN. I have ordered 10 SN74161 from Sydney. I have checked the board, as much as my sanity allows.  When I short D6 Pin 1 to CLA, I get a screen full of ASCII charcters. Afterwhich the screen can be cleared, back to the 20 x 24 dot matrix. If anyone can help, that would be great.

 

 

RussellSpeight1967's picture
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Here is an example of the
Here is an example of the screen, after shorting pin 1 and pin 2 on D6 a few times.
Macintosh_nik's picture
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Hi RussellSpeight1967!

Glad you're with us! Can I see a good photo of your replica so I can see the markings on your components? And the back side too if it has any mods on it. Do you have the correct power supply values? That's probably a good place to start....

RussellSpeight1967's picture
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Photo's of Apple 1
Hi, I'll send photos over in a few minutes, its a public holiday here is Australia, so time to play.  By touching pin 1 on D6, and sometimes get close to the image on page 17 of Mike's document, and the "@" symbols are flashing.  Please remember my soldering skills are not what they used to be when I was younger :-)
RussellSpeight1967's picture
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Posted Photo's onto a Google

Posted Photo's onto a Google Drive, which I directly messaged Macintosh_nik :-)Thanks,Russ.

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