is 7.5v 2.0A enough power for a Apple I + Mult-I/O board?

Get help here getting your replica 1 going

is 7.5v 2.0A enough power for a Apple I + Mult-I/O board?

Postby jquas » Aug Mon 08, 2011 10:45 pm

I assembled an apple I replica TE kit over the weekend. Everything works except I can't write to the rs232 port. I do, however, see everything I type on the keyboard and everything output to the screen duplicated to the rs232 port. I'll continue tracing and debugging that next weekend, I'm not writing about that.

I also assembled a multi-I/O card. I left the max232 chip and 10uF caps removed. I used it for a good hour, reading and writing to the EEPROM. Hum-diggity. I was having a time, everything tested A-OK, toyed with Krusader and some small programs.

Wanting to dump some programs over serial, I did some continuity tracing for the half-duplex serial issue, and reflowed a few solder points around the max232, the db9 port, and the 4 pairing propeller pins. I would expect if i "type" into the serial port, I should see its output on the screen. I have not yet, before or after. I'll continue debugging that, but...

Since then, the 6502 CPU seems unstable ONLY when the multi I/O board is installed, though it was left unmodified and working earlier. When it is removed, the apple I works fine. When installed, it would freeze or trap after some seconds, sometimes it could resume, most times needed a reset. Sometimes after 'reset', garbage outputs, and sometimes (and most times, lately), nothing happens at all, just an unmovable @.

So this begs the question, I'm using a brand new 7.5v 2.0A DC adapter. This "feels" like a computer starved for power -- is 2 amps enough at 7.vDC? Would anything else be responsible for this behavior?

Thanks,
jq

(I seem to have poor luck. I assembled a PockeTerm, it functioned fine on first boot using a 9v 600mA power adapter. I put it in the acrylic case, and it stopped functioning, bah! After hours of debugging and replacing a questionable .01uF cap and 5v regulator, and reflowing every solder point multiple times, it still only goes so far as to blink the KBD lights.)
Last edited by jquas on Aug Tue 09, 2011 7:35 pm, edited 2 times in total.
jquas
 
Posts: 3
Joined: Aug Mon 08, 2011 10:15 pm

Re: is 9v 2.0A enough power for a Apple I + Mult-I/O board?

Postby jquas » Aug Tue 09, 2011 7:34 pm

Ahh, well, here is a half-answer. I was actually using a 7.5 2.0A, and no, I don't think 7.5 2A is enough.

Once I used a 9V 5.0A, the serial accepted input!

The multi i/o board, however, still crashes the cpu. A friend is providing me a chip remover and I'll reseat the chips and try it again.
jquas
 
Posts: 3
Joined: Aug Mon 08, 2011 10:15 pm


Return to Troubleshooting

Who is online

Users browsing this forum: No registered users and 2 guests

cron