Fitting a Low-Profile Floppy Drive

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displaced
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Fitting a Low-Profile Floppy Drive

Postby displaced » Wed Jul 12, 2017 9:41 pm

Hi,

My aim is to mount a 'slim' 3.5" HD floppy drive into my Falcon, with an SD Card slot (IDE HDD) sat above it, then 3D print a nice plate for the casing to make the whole thing look neat.

I've got everything I need, but am struggling a bit with getting the drive to work.

I've got two drives - a Sony MPF-820 and a Teac FD05-HG. Neither have an obvious Drive Select jumper or solder point.

The drives have 26-pin connectors on their PCBs, but the attached ribbon cable have standard-looking 34-pin female IDC connectors and separate standard 4-pin connectors for power.

I naively built an adapter to go between the female sockets on the Falcon ribbon cable and the connector on the drives -- just two 34-pin IDC connectors soldered back-to-back, pin-to-pin straight-through affairs.

Needless to say, this didn't work. However, it at least behaved as expected when connected upside down -- the permanent-on floppy activity light (and on the Teac, an always-on motor).

Connected up the 'correct' way, the drives do nothing and GEM reports drive not found.

Looking at a few pinouts, it seems that Pin 4 on a 26-pin connector is Drive Select. With my multimeter, I found that Pin 4 on the PCB was presented as Pin 14 on the 36-pin socket at the end of the drives' ribbon cable. However, everything I've read about modding a PC 'DS1' drive to DS0 seems to involve connecting pin 12 to 10.

So I'm at a bit of a loss (and don't want to go monkeying about and frying the Falcon's floppy controller!). Has anyone had any joy getting these sorts of drives to work on our Ataris?

(btw, in the meantime, I've got a bunch of male-to-male breadboard wires arriving tomorrow that'll let me bridge the floppy and falcon data cables via a breadboard so I can experiment with the pin-to-pin mapping without building cables. When I find the correct pinout, I've got a couple of cable-mount 34-pin male IDCs and some ribbon cable to make up a proper cable).

displaced
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Re: Fitting a Low-Profile Floppy Drive

Postby displaced » Thu Jul 13, 2017 10:44 pm

Ok -- so I've got a bunch of wires and breadboard.

All the odd-numbered pins on the Falcon ribbon and the Drive ribbon are connected to eachother.

All the even pins I've connected one-to-one, via the breadboard so I can experiment.

I've tried swapping 10 and 12 by moving pins on the board -- no joy with either my Sony or Teac drives.

Can I just double-check: is the Falcon's cable soldered in 'correctly' -- i.e. Pin 1 really is indicated by the red-coloured edge of the ribbon?

Power at least seems fine - the drive makes a single brief whirr as soon as the power's turned on, but nothing after that -- GEM reports "Drive A: does not exist".

It seems so simple - swap pins 10 and 12... done. I'm not sure why I'm having so much trouble!

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Bama
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Re: Fitting a Low-Profile Floppy Drive

Postby Bama » Fri Jul 14, 2017 11:51 am

Hi displaced,

I have read your posts. No answers for you but I don’t want you to think no one is hearing you.
:-)
BAMA

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Re: Fitting a Low-Profile Floppy Drive

Postby mpattonm » Fri Jul 14, 2017 2:16 pm

One of these https://www.google.com/search?q=fdd+and ... ader+combo might save you from some part of trouble. Its typically low profile FDD with regular 34 pin FDD connector combined with card reader. But you will still have hard times forcing that drive to ID0 setting. As far as I know noone has done this yet.

displaced
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Re: Fitting a Low-Profile Floppy Drive

Postby displaced » Sat Jul 15, 2017 9:18 pm

Thanks for the replies!

Ok - with my crazy breadboard setup, I've found that disconnecting pin 14 and connecting it to pin 10 on the floppy side makes the drive work.

Just formatted an HD floppy successfully. Yaaay!

I think these slim drives might make some of the signals 'multi-purpose'. Still, it doesn't really make sense because I'm apparently connecting DRVSA to MOTEA... which doesn't exactly fit with the idea of swapping DRVSB/A.

I'm off to make a ribbon cable!

And for posterity, here's the craziness, which, now it works, I'm quite proud of :lol:

IMG_0818.JPG.jpeg
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displaced
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Re: Fitting a Low-Profile Floppy Drive

Postby displaced » Sat Jul 15, 2017 10:39 pm

Damnit....

Ribbon cable made... went to put the connectors on and it seems I've got the wrong type. They're cable-mount, male -- correct number of pins correct pin pitch...

...but the pins themselves are too thin and not quite as long as they should be.

Looks like another order to RS Components is needed!!

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Re: Fitting a Low-Profile Floppy Drive

Postby Bama » Sun Jul 16, 2017 11:38 am

Nice! It's a cool feeling when you things to work!

Did this wiring work with both the Sony and the Teac?
:-)
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Re: Fitting a Low-Profile Floppy Drive

Postby 1st1 » Sat Jul 29, 2017 9:22 am

I did this already on my two Falcons and one the of a friend. You need an adapter for slim floppy to standard 34 pin connector, they are available as accessories for some rack servers. Mine were for servers from Fujitsu-Siemens. You need also to know, that such PC slim floppys are set to operate on DS1 signal and they are not configureable. My solution was just to short DS0 and DS1 on the slim floppy adapter, the signals are neighbours on the connector so a bit of solder tin was enough to make the shortage. I made a frame of aluminium sheet, and the prototyoe to get the sizes for this was made from paper. See attached pictures.
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