Amiga 2000 Floppy Drive problem

Teo Zenios teoz at neo.rr.com
Sat Jul 2 13:16:03 CDT 2005


----- Original Message ----- 
From: "Ethan Dicks" <ethan.dicks at gmail.com>
To: "General Discussion: On-Topic and Off-Topic Posts"
<cctalk at classiccmp.org>
Sent: Saturday, July 02, 2005 5:56 AM
Subject: Re: Amiga 2000 Floppy Drive problem


> On 7/1/05, Teo Zenios <teoz at neo.rr.com> wrote:
> > Jumper 301 is still in the open position (for a single drive).
>
> Perfect.
>
> > The two 8520's looked ok (nothing shorting pins together or stuff like
that,
> > no signs of overheating). I swapped the 2 chips around and still have
the
> > same result (external Df2: works while the internal DF0: is dead).
>
> OK... swapping the 8520s and watching the symptoms was a pretty
> standard method back in the day - it's easy and it works, so that
> _probably_ shows your 8520s are OK.
>
> > I checked the floppy cable and didn't see anything out of the ordinary
> > (except a pin in what looks like position 2 of the cable but I think
that is
> > a key, since the motherboard does not look like it has a broken pin on
it).
>
> That _is_ a key (and needs to be in any Amiga hardware FAQ - I can't
> remember how many times we had to tell people that in our Amiga club -
> every novice who added an internal floppy use to call us up and ask
> how to "replace a broken pin"... they thought that the
> pin had become stuck, and they must have pulled it out when they
> messed with the cable.
>
> > At this point I think it either the floppy cable has a bad line, or the
> > drive is just dead. Since the amiga cable does not look like a standard
> > floppy cable I think I will try setting the drive for Df1: and shorting
> > Jumper 301 to see if its recognized at all.
>
>
> > I did some research and quite a few older DD 3.5" PC drives can be
jumpered
> > to Amiga mode (ofcourse I don't have any on the list).
>
> And they support the /DISK-EXCHANGE signal (p 34?)   That was what
> always hosed frugal early-adopters of the Amiga - they'd try to use a
> cheap floppy, and the OS wouldn't be able to step the drive in and out
> one track to get the drive to assert the /DISK-EXCHAGE (or whichever
> one it was) so that the drive could 'tell' the OS that the diskette
> that used to be there isn't there any more.
>
> You _can_ hook up a floppy drive that won't assert that signal, but
> that places a burden on the user's head to have to type an AmigaDOS
> command to flush the previous diskette's particulars and to cache the
> new diskette.
>
> -ethan
>
This link shows how to modify a specific PC floppy to work perfectly on an
Amiga (pin 34 goes to pin 2)

http://www.caps-project.org/articles.php?id=a_v9drivemod

Anyway while checking for Amiga compatible PC drives in my piles of stuff I
came across a HD to floppy power connector (was stuck on a floppy drive) I
decided to try it out on the Amiga. The drive works! I then checked the
voltage at the old amiga power connection and it does show 5V and 12V (using
a multimeter). So either there is a loose connection inside the power cable
or its pinched somewhere so that under load the voltage drops enough so that
the drive wont work. Anyway I kept the power adapter in place (along with a
Y cable so I can power my 2GB HD) and everything works just fine for now
(even with the case back on) so I am happy.

I must say that with a 2.x kickstart  and Workbench 2.1 this GVP 030/40
boots up one hell of allot faster then it did in its Kickstart 1.3 days. Too
bad all my other machines can't go from power on to desktop in under 15
seconds (from a HD boot about 10 seconds for my A1200).

Thanks for the help Ethan.











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