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

PostPosted: Aug Mon 08, 2011 10:45 pm
by jquas
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.)

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

PostPosted: Aug Tue 09, 2011 7:34 pm
by jquas
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.