On Mon, 23 Mar 1998, Tony Duell wrote:
At the back of
the main circuit board, just in front of where the ribbon
cable connects to it, there is a 14-pin chip with a label "1F" beside it.
In drive A, there is an empty 16-pin socket beside it, with "2F" written
on the circuit board beside it. Drive B has something IN this socket - a
BLUE 16-pin chip.
Sounds a little like a Tandon drive, although those normally had the
jumper in location 1E (or at least the schematics I have show it there).
I believe it is a Tandon drive.
I am unable to view the main circuit boards of the drives because they're
in a metal box, but if 1E is directly in front of 2E, then yes, I believe
I'll find the jumpers there. I've found labeled photographs of a Tandon
drive in an old issue of 80 Micro.
<snip>
The 14 pin 'chip' is the jumper pack. Alas the
schematics I've found show
a _16_ pin jumper at location 1E with the following functions :
1-16 Enable head load on drive selected
2-15 Drive select 0
3-14 DS1
4-13 DS2
5-12 DS3
6-11 Mux (drive _always_ enabled)
7-10 Not used
8-9 Eanable head load on motor on
The photos show a 16-pin socket, filled with a 14-pin "DIP shunt", with
only four switches in it, corresponding (I think) to DS0-DS3.
I've also found a later version of the drive with
a 14 pin jumper at
location 'U8'. It has the following functions
1-14 Enable head load on drive selected
2-13 Drive select 0
3-12 DS1
4-11 DS2
5-10 Mux (drive _always_ enabled)
6-9 DS3
7-8 Eanable head load on motor on
How similar in appearance are these two drives? The one in 80 Micro (#56,
Sept. 84) appears identical to the drives I have, at least as far as my
limited viewing window allows me to see.
At any rate, once I manage to remove the drives from their housing, I'll
find the jumper blocks.
<snip>
There are 3 common '6-sided' screwdrivers :
Allen hex - a true hexagonal tip, which come in inch and metric sizes
This is the one I need. Possibly in metric sizes as none of the imperial
ones I have fit.
Torx - looks like a 6-cycle 'sine wave'
wrapped around a circle. This one
is common in computer equipment
And quite annoying. :)
Bristol Spine - has 6 _square_ splines (sometimes only
4). This one is
common in Friden machines, and in some IBM stuff.
I don't think I've ever seen this one.
Thanks again!
Doug Spence
ds_spenc(a)alcor.concordia.ca