Re: Problems! Disk ][ drive just whirs and whirs; IIc monitor knob stuck; IIe enhanced not...

[Larry Stedman <stedman@binghamton.edu>]

Motherboards on the 2 unenhanced are both 1982
with a number 820-0064-B   (Or is the last 8?  Maybe B given Matt's info 
about revision A.  )  There is also a number underneath that in white:   
607-0164-M on one and the other lacks the letter.

The enhanced is from 1984.  

I tried comparing them to see I could spot the board differences--they 
look identical!  Then realized from David's comment that it's not that 4 
new, *extra* chips were added-- just the electronic innards of the chips 
that were changed.  I had thought I could spot a CPU chip that would be 
marked 6502 or 65C02---would have been too easy!

Is there an easy way to tell if these unenhanced have the 65C02 and/or 
the newer character generator ROM?    IIRC, one can run certain programs 
that use MouseText to check the character stuff.

The 1988 plantinum IIe with a numeric keypad must have been a lot 
wider... but sounds cool.

As to the drives... I tried swapping them--- neither makes the startup 
rattling noise.  I'm definitely leaning towards the controller gone bad 
idea.

Michael, thanks for the advice.  I'm not an electronics guy, so don't 
have a spare 74LS259 chip lying around--- maybe there is one, though, on 
one of the other controllers that I could steal from.  But first I will 
try reseating chips per David's advice and try that chip first!

There is something remarkably satisfying about mucking around with a 
computer's innards and tweaking this and trouble-shooting that!  
Appreciate the input.

Larry Stedman
Suburban Milky Way