Hitachi FDD-412A 8 inch floppy drive

m.vgunten
Posts: 19
Joined: Sat Jan 18, 2020 5:56 pm
Location: Bern, Switzerland

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

max33cs wrote:
Thu Dec 24, 2020 6:57 pm
197 / 5000
Risultati della traduzione
hi, if you managed to get the emulator to work, i want to buy one of these, i have okuma lb12 lathe with osp, year 1987, used this 8 inch reader, wait for your reply thanks
Our 8 inch emulator is currently on hold as we follow another approach. I will inform you as soon as we have found a solution!

mrwing
Posts: 1
Joined: Wed Jan 13, 2021 4:28 pm

Re: Hitachi FDD-412A 8 inch floppy drive

Post by mrwing »

This is really THE thread i have been looking for.
Been all around to see if i can somehow connect a floppy sim to our old OSP5000 mill (MC-6VA).
already looking at different ways to backup the data on the 8" like with Kryoflux and similar tools.
will look forward to the development of this thread.

CNC_USER
Posts: 3
Joined: Sun Apr 18, 2021 1:22 am
Location: Rezekne, Latvia

Re: Hitachi FDD-412A 8 inch floppy drive

Post by CNC_USER »

Hello! :)
I also have OKUMA MC-4VA milling machine which has this Hitachi drive. And how it always happens -system needs to be reloaded. Unfortunately that's not the only problem here- I have found that terminator resistor array inside of floppy drive was crumbled, did find a replacement but drive still isnt working. Im waiting for an FDC floppy controller board to test if the problem possibly is in board. Can I ask m.vgunten to measure resistance between GND and +5V line on FDD-412A board where connectors for floppy and power cable is located?
By the way- in attachements there is FDD pinouts and connections to OSP5000 FDC board that I got from manuals I have for my machine. Hope it can somehow help. One of the possible solutions would be to make a dump from original 8'' floppies and write it to a 3.5'' floppy (OKUMA OSP5000 and OSP5020 systems have an option of FRP board that is used together with 3.5'' drives). Older OKUMAs are beasts- mechanically everything is in perfect state, CNC system also works, only headache is created because of these oldschool 8'' floppies.
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m.vgunten
Posts: 19
Joined: Sat Jan 18, 2020 5:56 pm
Location: Bern, Switzerland

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

CNC_USER wrote:
Sun Apr 18, 2021 1:41 am
Can I ask m.vgunten to measure resistance between GND and +5V line on FDD-412A board where connectors for floppy and power cable is located?
Unfortunately I don't have access to the drives anymore, but I will see what I can do. Sorry for that.
CNC_USER wrote:
Sun Apr 18, 2021 1:41 am
By the way- in attachements there is FDD pinouts and connections to OSP5000 FDC board that I got from manuals I have for my machine. Hope it can somehow help.
Thanks, this is certainly helpful, for me and other readers!
If your documentation shows some more details about the Hitachi FDD-412A jumper settings (meanings of each jumper) this would be also useful :)

CNC_USER
Posts: 3
Joined: Sun Apr 18, 2021 1:22 am
Location: Rezekne, Latvia

Re: Hitachi FDD-412A 8 inch floppy drive

Post by CNC_USER »

m.vgunten wrote:
Mon Apr 19, 2021 7:12 am
If your documentation shows some more details about the Hitachi FDD-412A jumper settings (meanings of each jumper) this would be also useful
I have information about jumper settings on different OSP5000 CNC system boards, but unfortunately there is absolutely no info on these drives. :(
m.vgunten wrote:
Mon Apr 19, 2021 7:12 am
Unfortunately I don't have access to the drives anymore, but I will see what I can do. Sorry for that.
Thats ok. I just wanted to compare that resistance. When terminator resistor (completely new) array is installed, resistance between GND and +5V line is suspiciously low- 27 ohms. Even with removed array resistance is approx. 87 Ohms, which is also too low for circuit based on 74LS logic. Capacitors was the first thing I changed- result stay the same. Something is wrong there.
At the moment I have called to a friend asking if he have some spare floppy drive in a factory he works. Really want to get that machine in a working state. Another hope is one of my old friend who owns a private PC museum, maybe he can lend me 8'' floppy I can connect to Kryoflux.

CNC_USER
Posts: 3
Joined: Sun Apr 18, 2021 1:22 am
Location: Rezekne, Latvia

Re: Hitachi FDD-412A 8 inch floppy drive

Post by CNC_USER »

So here is the news: my FDD-412A isn't working (hope it is not one of these HITACHI modules, will look at electronic a bit later), I received an FRP board for OKUMA and 8'' floppy adapter from DBIT. How stupid is an idea of reading data from 8'' floppies (with the help of Kryoflux) and writing that dump to a new 3.5'' disk? I know there is a difference in speeds, what other obstacles can I face here? Floppy controller on FRP board is D72065C.
I know You guys have more experience in these questions. I think together we can come to some result.

m.vgunten
Posts: 19
Joined: Sat Jan 18, 2020 5:56 pm
Location: Bern, Switzerland

Re: Hitachi FDD-412A 8 inch floppy drive

Post by m.vgunten »

CNC_USER wrote:
Sun Apr 18, 2021 1:41 am
Can I ask m.vgunten to measure resistance between GND and +5V line on FDD-412A board where connectors for floppy and power cable is located?
Sorry for my late answer. I'm not sure if this is still of interest ... anyway, a colleague of mine has measured the following values on two floppy drives:
24.7 Ohm
26.4 Ohm

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