Hitachi FDD-412A 8 inch floppy drive

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m.vgunten
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Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Sat Jan 18, 2020 6:06 pm

Dear disk experts

I am trying to emulate/replace a Hitachi FDD-412A 8" floppy drive with my HxC Floppy Emulators (have both SD and Gotek). Unfortunately I do not have any documentation for this drive and its 50-pin IDC ribbon cable connector. It also seems impossible to find any details in the web :(.
The only thing I understand: it is not a standard Shugart connector (NOT as documented under https://old.pinouts.ru/HD/8InchDisk.shtml)!

Has anybody successfully replaced this kind of floppy drive? Who can deliver further information about IDC pinout, signals, ...?

The drive is connected to an Okuma Campus 5000 CNC System an data should be recovered to allow drive replacement.
As far as I know, the system works with SS and DS disks having SD and DD.
You can find pictures of the drive on http://www.retrocomputing.net/index.php ... Fotografie

Any help is appreciated - Thanks
Martin

Jeff
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by Jeff » Sat Jan 18, 2020 9:19 pm

Lot's of IC on this drive... Can you make a better picture of the PCB ?

m.vgunten
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Joined: Sat Jan 18, 2020 5:56 pm

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Sun Jan 19, 2020 11:37 am

Hi Jeff
Here are some images of the Drive and the PCBs.
Thanks for your help!
Martin
Attachments
FloppyDriveBottom.jpg
FloppyDriveBottom.jpg (122.8 KiB) Viewed 454 times
FddPcbTop.jpg
FddPcbTop.jpg (171.69 KiB) Viewed 454 times
FddPcbBottom.jpg
FddPcbBottom.jpg (165.45 KiB) Viewed 454 times

m.vgunten
Posts: 8
Joined: Sat Jan 18, 2020 5:56 pm

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Sun Jan 19, 2020 11:41 am

Trying to understand the pin assignments on the 50-pin IDC connector I followed the PCB traces ... still a work in progress.
I will also try to find some Okuma Maintenance Manuals.
Attachments
Hitachi_FDD-412A-IDC_50p.png
Hitachi_FDD-412A-IDC_50p.png (200.19 KiB) Viewed 444 times
Last edited by m.vgunten on Sun Jan 19, 2020 2:29 pm, edited 1 time in total.

Jeff
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by Jeff » Sun Jan 19, 2020 1:02 pm

I use here an YD-180 to dump 8" floppy disks and this one also use a non-standard pinout, maybe this is the same as your drive pinout.
The YD-180 is equivalent to this one :
https://deramp.com/downloads/floppy_dri ... Manual.pdf

If you have an oscilloscope you can check if the read data line match with the above pdf.

m.vgunten
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Joined: Sat Jan 18, 2020 5:56 pm

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Sun Jan 19, 2020 2:34 pm

Unfortunately it is not looking like a YD-180 pinout. I have most of the signals on odd pin numbers and measured the /INDEX pulse on pin 7. Just updated the table above ...
Thank you anyway!

m.vgunten
Posts: 8
Joined: Sat Jan 18, 2020 5:56 pm

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Mon Jan 20, 2020 2:49 pm

Here some additional images of the Floppy Controller PCB.
FdcPcbTop.jpg
FdcPcbTop.jpg (158.36 KiB) Viewed 411 times
FdcPcbBottom.jpg
FdcPcbBottom.jpg (124.46 KiB) Viewed 411 times

Jeff
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by Jeff » Mon Jan 20, 2020 6:23 pm

Is there a NEC 765 floppy controller ?

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Mon Jan 20, 2020 10:08 pm

Bingo! :D

Thanks a lot your hint will help finding the signals on the floppy connector!
NEC-D765AC.jpg
NEC-D765AC.jpg (23.25 KiB) Viewed 396 times
NEC-D765AC-pinout.jpg
NEC-D765AC-pinout.jpg (9.67 KiB) Viewed 396 times
http://www.cpcwiki.eu/imgs/f/f3/UPD765_ ... _OCRed.pdf

Jeff
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by Jeff » Mon Jan 20, 2020 11:03 pm

m.vgunten wrote:
Mon Jan 20, 2020 10:08 pm
Bingo! :D

Thanks a lot your hint will help finding the signals on the floppy connector!

NEC-D765AC.jpgNEC-D765AC-pinout.jpg
http://www.cpcwiki.eu/imgs/f/f3/UPD765_ ... _OCRed.pdf
Yes. And we now know that the sector format used is pretty standard ;).

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Sun Jan 26, 2020 6:19 pm

Updated pin assignments on the 50-pin IDC connector after having a closer look to the floppy controller PCB ... still a work in progress.
Hitachi_FDD-412A-IDC_50p.png
Hitachi_FDD-412A-IDC_50p.png (57.33 KiB) Viewed 293 times

m.vgunten
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten » Sun Jan 26, 2020 6:30 pm

I can now control the floppy drive and read some date on the /RD pin - see bottom line in diagram below.
I further assume data separator clock /SEPC and data /SEPD on the two lines above (D16&D17) ... but I'm not sure at all!
FdReadDataSample.png
FdReadDataSample.png (60.67 KiB) Viewed 293 times

Jeff
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Re: Hitachi FDD-412A 8 inch floppy drive

Post by Jeff » Mon Jan 27, 2020 8:49 am

m.vgunten wrote:
Sun Jan 26, 2020 6:30 pm
I further assume data separator clock /SEPC and data /SEPD on the two lines above (D16&D17) ... but I'm not sure at all!
Yes for sure this is data separator outputs !

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