Amiga hardware info, help and support with a focus (but not limited to) North American NTSC experiences. Open to all.
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McTrinsic

by McTrinsic posted Sun Feb 24, 2019 8:24 am

Hi all,

you may or may not remember the Phoenix in the showroom in this forum.

Unfortunately, the internal floppy has had its day. It is a modded DELL HD-Drive for the Amiga. If I connect it now the PAL chip gets hot.

It is this one (sorry German)

For whatever reason the ‘foil‘-cable had some burned marks. It doesn’t work anymore. Over the time I have collected two more of the external drives and one of the actual Floppy drives to see if I could exchange them for spare parts. In short no combination works.

So I would like to ask if I one of our gurus here could help with repairs. I already asked Hese (Amibay) and a Floppy-guru in A1k.org but they declined. Out of the three I‘d love top have one internal back working. An additional working external one would of course even be better.

The topping would be if one here could disassemble/read out the PAL on the adapter. The PAL has on it „PALC22V10-25PC“.
That would mean that the Amiga community would have a cheap way to get new HD-Floppies as the actual drives are still around...

Thanks,
McT
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intric8
Seattle, WA, USA

by intric8 posted Sun Feb 24, 2019 11:10 am

Oh man, this situation on your hands brings back some rough memories for me when I dealt with my own internal drive.

I can only speak from my own personal experience with the Sony drives that are available and technically made for the A500. They work very well and are reliable from what I've seen. The hardest part (and it was hard) was getting it perfectly aligned using the old bracket, which required custom holes to be drilled in that very solid metal. And lots and lots of adjustments, which was a total PITA.

Repairing a floppy drive would be some serious mad scientist work. Do none of your spare drives that you collected along the way work? Were they all "dead" when you got them, to use for parts?
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McTrinsic

by McTrinsic posted Sun Feb 24, 2019 11:17 am

Well I have a drive that works - a "Micronik HD Drive".
Might be similar to the "Amtrade real HD Drive".

Only issue is: its too big for my Phoenix.

So in total I have three actual drives wit one of them being NOS.

I have three of the PCBs with the respective PALs out of which one gets hot.

And I have the Micronik HD Drive that I hope could be modded as an alternative to fit the slimline floppy-drives.

The issue seems to be at least to some part the foil-like cables.
When the actual "wire" breaks the wire burns - thats how it looks like to me.

Help! :)
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Christian

by Christian posted Thu Apr 25, 2019 4:30 pm

The GAL most likely performs one or two functions:

a) It will send the correct ID sequence for the floppy depending on whether an HD or a DD floppy is inserted (this is necessary so that Amiga OS knows whether it should read/write/format in 880K or 1760K)
b) (possibly) it will switch the drive to a 150 RPM when an HD disk is inserted (if the drive doesn't do that automatically - in which case one of the pins on the drive must control that)

Check with MGR3SA on A1K. He is converting Sony MFP920 drives to Amiga HD floppies and he adds exactly such a GAL . He may be able to program a new GAL (with his own logic) by just adjusting the GAL type (I think he uses one that is different from the PAL that your Dell floppy has) and the how it is wired.

PAL = Programmable Array Logic - one time programmable via fuse map
GAL = Generic Array Logic - erasable, reprogrammable. Generally a replacement for PALs
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McTrinsic

by McTrinsic posted Fri Apr 26, 2019 8:21 am

Hi,
thanks for the infos.

MGR3SA already had this one in his hands and sent them back.

AFAIK the Sony he provides are PC-HD but Amiga-DD. Had one myself.

So in order to help the Amiga community with some new (NOS) HD-FDDs I am still looking for someone to try to read out the PAL.

Cheers,
Erasmus

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