No input from keyboard. Did I fry my Apple I replica?

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colerise's picture
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No input from keyboard. Did I fry my Apple I replica?

Hello! I'm currently experiencing an issue where I'm getting flashing @_@_@_@ at start, can clear and reset via my Apple II keyboard (which has 5v and lights up) but not getting any input from the ASCII keys. I was using a wire to short the pins manually to clear screen before modding the keyboard. It's possible I tapped the wrong pin, or - and be gentle - may have had the DIP in backwards at one moment. I'm not entirely sure.

 

While debugging:

- I tried replacing the PIA on the motherboard with an origianl AMI, and swapped the 7404 on the daughter board w/ a new one from Mouser, to no avail. 

- The keyboard did input once before the issue, as I was able to input and run the ASCII test program. All keys worked and OH my, what a feeling that was.

- I triple checked the wiring from the Keyboard to the DIP, which was configured using this guide: https://www.applefritter.com/appleii-box/APPLE1/Bilder/Using%20Apple%20II%20Keyboard%20for%20Apple%201.pdfWhat should I check or aim to replace next? I'd be enormously grateful for any guidance at this point. I have the utmost respect for the folks on this forum, generating a wealth of historical preservation. Separately, I do have some extra period accurate parts for a Byte Shop case build (using Sepele so it's clearly fake) which anyone is welcome to. They include a littlefuse holder, an amphenol convenience port, a red 120V switch that matches Apple 1 #39 from the Science Museum of London, if anyone is missing a part. 

I've also built a Telnet service that uses OpenAI to generate any image you can dream of, and return it as ASCII for the Apple 1, using P-lab's amazing wifi board. Will post more about that soon!

 

Best, CR.

 

 

 

 

 

 

 

 

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Hi colerise!

Your replica looks great!

Do you have an Apple II to test your keyboard? Just in case, I'll attach the schematic I used to build the adapter for the Apple-1 myself

 

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Hi, As the video section does

Hi,

 

As the video section does more less all you describe of it's own it's unclear if the CPU part of your Apple I is working at all.

Do you get the prompt when reseting?

If not it seems you 6502 part is not running.

If you get the prompt you can simulate the keyboard by pulling strobe via a 1k resistor high.

To get some input you need to put some bit pattern on D0-D6.

D7 needs to be connected to 5v.

If you toggle strobe with out any connection you should get an @-sign.

With D0 and D7 to 5V it should result in an A.

https://www.applefritter.com/appleii-box/A19_apple1Datanetics.htm

 

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Hi Cole,congrats on your

Hi Cole,

congrats on your build and thank you for the nice words, cant' wait to see the OpenAI thingy... :-D

 

Uhm, you've already replaced the 7404 on the daughterboard, which is what usually fails when you reverse the direction of the flat cable, good.

 

RESET and CLEAR SCREEN should work anyway so you should be able to have the "\" prompt even if the keyboard is not working,

 

If so, check the +12V and -12V power supplies, as well as the +5V. Also check for any burnt tracks/vias on the daughterboard or any breaks on the flat cable.

 

I would then check if the keyboard is working by using an oscilloscope and checking the output lines and strobe signal which should be handled by U1 (7400, have a look at it as well).

All output lines (except the strobe of course) are latched so it's easy to check them one by one and see them changing with keypresses, even directly from the PIA socket (PINs 2 to 9, plus 40 for the strobe).

 

If all the data lines and the strobe are working, the problem could be on the motherboard... :'(

 

Good luck and please keep us posted...

Claudio - P-LAB

 

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FIXED

IT WORKS! Thanks again for all of the help! Turns out it was a bad 7400 chip. 

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Excellent!

Well done! :-)

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CongratulationsWhich one was

Congratulations

Which one was it? IC B1, C15 or D10?

colerise's picture
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Daughter board

It was one of the two on the daughter board of the keyboard, thankfully!

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Arn't there two 7404?

Arn't there two 7404?

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two 7400, and one 7404, on

two 7400, and one 7404, on the datanetics apple II plus. replacing the 7404 did nothing, so i ordered and replaced the rest. i could've done one at a time to find the chip, but was impatient to eliminate the keyboard if it was a motherboard issue. thankful for the issue, and all the amazing help, because situations like these force deeper understanding, especially as a n00b to Apple 1. prior to this, had no idea what a 7400 did, let alone the 555 timer. fascinating! 

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