Re: IIgs / Duo Disk / Monitor 100 compatibility question

[Rubywand <rubywand@swbell.net>]

Dave Althoff writes ...
> 
> Greg Cifu (gcifuREMOVETHISSTUFF@hughesANDTHISSTUFF.net) wrote:

 ....
> 
> : Will the GS motherboard control the DuoDisk right from the motherboard or
> : must I install the card (seems like a waste of a port)? If it will, can I
> : cascade a 3.5 either before or after it?
> 
> Yes.  If you add a 3.5 drive, hook up the 3.5 drive first and daisy-chain
> the Duo off of it.  There is a hardware mod for the Duo, requiring the
> clipping of a resistor to keep the power draw down, but I don't have the
> details handy (I've done that to all of my Duos already).
> 


     Below are the details from the A2 Csa2 Floppy Disk FAQs on Ground
at ...


ftp://ground.isca.uiowa.edu/2/apple2/Faqs
http://ground.isca.uiowa.edu/2/apple2/Faqs


Rubywand

____________________


>>

From: Steve Jensen

020- What DuoDisk mods are necessary?

     The following is excerpted from an info file from my old bbs ...
 
     There are TWO modifications that should be made to Duodisk drives:
 
     The First one was recommended by Apple several ago to solve
occasional problems with trashing diskettes. The solution is to remove 2
capacitors.

     The Second modification is only required to solve a problem with
daisy-chaining on the GS Smartport, though the modified Duodisk will
still work fine on older Apple II's. It requires removing a resistor.

 

DUODISK MODIFICATION #1- REMOVAL OF TWO CAPACITORS
 
     This mod should be done on ALL Duodisks, no matter whether they're
used on //e's, IIGS's, etc.  The problem was that diskettes would
sometimes be damaged when doing an Open-Apple-CTL-Reset or when using
disks with certain kinds of copy protection.  The mod was in an Apple
dealer service bulletin several years ago for "analog board PN 676-[]101
or 676-[]102."
 
     The Analog board is the one inside Drive 1 in the Duodisk.  You may
have to unplug the cable near the back right of the board to see the
board's model number.  Anyway, if you have the -101 or -102 board, just
snip out Capacitors C29 and C30 at board locations A1 and B1,
respectively.
 

DUODISK MODIFICATION #2- REMOVAL OF A RESISTOR

     This mod should be done for Duodisks used with a GS; otherwise, it
is optional. The problem is that the Duodisk draws just a little too
much current when connected to the GS Smartport. This can render other
drives on the chain inoperable. Problems are MOST likely to occur when
the Duodisk is daisy-chained from a Unidisk 3.5 Drive.

     Remove the top cover and turn the drive so that the identifying
number will be at the bottom left of the analog board. The number might
read 676-[]101, 676-[]102 or
676-[]107.
 
If the I.D.# for the analog board is 676-[]101 or  676-[]102, use
a pair of nippers and cut out resistor R8 (located at position A2).
 
If the I.D.# for the analog board is 676-[]107, use a pair of
nippers and cut out resistor R39 (located at position A1).

----------------------------


From: Dave Althoff

     There are two capacitors which must be clipped from the board on
the DuoDisk regardless of what machine you intend to use them on. 
Failure to do this can lead to very nasty failures. For instance, some
copy-protection schemes can cause the drive to start writing
unexpectedly-- say, during a re-boot-- thus trashing the disk without
regard to the write-protect switch.

----------------------------

 ....

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Rubywand