email: desieh_at_southcom.com.au
desieh_at_bigfoot.com
museum_curator_at_hotmail.com
Apple Lisa Web Page:
http://www.southcom.com.au/~desieh/index.htm
thanks I'll have time in the next day or so to pull the thing apart and
relay back my findings............
-----Original Message-----
From: Tony Duell <ard_at_p850ug1.demon.co.uk>
To: Discussion re-collecting of classic computers
<classiccmp_at_u.washington.edu>
Date: Saturday, May 30, 1998 9:03
Subject: Re: Original IBM PC (was Re: Prices to pay for old
>[IBM PC floppy drives]
>
>> I get nothing out of them, no motor spin up, no led, no
>> nothing...................
>
>I've got the Type 1 drive schematics here (from the O&A TechRef volume 1).
>
>Let's go through the obvious things first.
>
>You have a DIP shunt (a little plastic block with shorting bars) in
>socket 1E of both drives, right? And a termination resistor pack in
>socket 2F of the drive physically furthest from the controller.
>
>Check that the cables on J4 at the back of the logic board are connected
>properly. There are some blank pins (4?) nearest to the edge connector,
>and then P8-P12 in order along the pins.
>
>Also, check the supply voltages - +5V and +12V at the drive when the
>machine is turned on. You do have the power cables plugged in, I trust
>:-) (don't laugh - I've forgotten them).
>
>OK, let's sort out the lack of LED first. Unplug the cable from the
>controller (leave it hooked up to the drives) and turn on the machine.
>
>Ground pin 3 of IC 3E (a 7407) in the drive. Does the LED come on now? If
>so, then suspect the controller, DIP shunt or cable. If not, then ground
>pin 4 of IC3E. If the LED now comes on, then IC3E is defective (or not
>geting power).
>
>Problem is, if IC3E is defective, then how many other parts have been
>damaged. 7407's are pretty reliable, so if it's damaged, it sounds like
>power problems. You didn't hook up the power cable backwards, did you?
>
>You can trace the motor on signal similarly. Try grounding pin 16 on the
>edge connector (the even numbered pins are on the top of the board,
>starting from the end nearest to the notch in the connector tongue), or
>equivalently pin 1 of IC3E. If the motor doesn't start,then try grounding
>TP13. If that starts the motor, IC3E is defective. If the motor still
>doesn't start then I'll have to talk you through the motor control board
>at the back.
>
>>
>>
>>
>
>-tony
>
Received on Fri May 29 1998 - 22:59:30 BST