Re: Replacement drive mechanism for 1581

On Thu, 26 Mar 2015, William Levak wrote:

> On Wed, 18 Mar 2015, geneb wrote:
>
>> On Wed, 18 Mar 2015, William Levak wrote:
>> 
>>> 
>>> The drive mechanism for my 1581 has stopped working. It was a Chinon 
>>> F-354E. I tried a Chinon FZ-357 as a replacement.  I could not get it to 
>>> work, even though I tried all the jumper variations that seemed 
>>> reasonable. I also have a Newtronics D359T3 and a Teac FD-235HF, but their 
>>> jumpers are not marked, and I don't know how to set them.
>>> 
>>> I know these are HD drives, but they should also be able to work in DD 
>>> mode.
>>> 
>> William, there's an issue of Commodore World that contains an article on 
>> what you need to do in order to use an HD mech in a 1581.  Unfortunately, I 
>> don't recall which issue it is.  The good news is that the IA has all of 
>> them scanned and online.
>> 
>> https://archive.org/details/commodore-world
>
> I looked up the article. Unfortunately, it's a little vague.
>
> You cut lines 3 and 34, and juper line 2 to ground.
>
> I can't make out what jumpers 1 and 2 do. The directions for jumper 2 say to 
> connect the open end of R2 to pin 34.  Does this mean that the line that was 
> line 3 is now line 34?  For jumper 1, it says connect the end of r15 to 
> ground. Does that mean that the remaining end of line 3 is grounded?

After lookin through all the specifications on the 1581 and PC connectors, 
I have concluded that it is not necessary to alter the 1581's system 
board.  All that is necessary is to modify the cable connecting the drive 
mechanism to the system board.

                 PC     1581
disk change     34      2
density select   2     not available, connect to signal ground
                        (any odd numbered line except 1)

Line 3 is not connected on the PC, but it might be on a drive mechanism, 
so it is best to avoid that line.

Lines that are connected to +5V have a pull up resistor; lines that are 
connected to ground do not, so I do not need a resistor on "density 
select".

In addition, the PC interface has lines for a second drive which are not 
connected to anything on the 1581, but the corresponding signal grounds 
are connected to ground (13, 17). The PC does not use lines 4 or 6, but 
their grounds are connected (5, 7).

Line 5 looks like the best choice for grounding "density select".



Some drive mechanisms have jumper blocks on them.  Now that I know which 
lines need changing, I can try using an ohmmeter to see if I can jumper 
them.


wlevak@sdf.lonestar.org
SDF Public Access UNIX System - http://sdf.lonestar.org

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