External 5.25" floppy diskette drive

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External 5.25" floppy diskette drive

Technical specifications

Inside this TAXAN external 5.25" floppy diskete disk drive is a TEAC FD-55BR 578U. Actually there is nothing special about this external drive. It is only the external DC37 connector/cable (with power supply) and the internal conversion to the 34 pin floppy cable and the 4 pin Molex power plug.

I have bought the diskette disk drive on eBay very cheap as an external drive for an IBM PC/XT. For this money you normally don't get a good working TEAC-FD55BR.

Pictures

TAXAN
TAXAN extern 5.25 floppy
TAXAN
DB37 connector to 34 pin floppy connector + power supply
TAXAN
TEAC FD-55BR 578U
TAXAN
TEAC FD-55BR 578U (PCB)
TAXAN
DC37 connector to 34 pin floppy connector + power supply

After unscrewing the case I took a closer look at the wiring and the power supply via the DC37 connector.

See there, the 34 pin cable was not installed correctly. Line 1 was connected to pin 34! I have marked the correct line 1 new in red and with the number 1! This drive was definitely not intended for an IBM PC/XT.

The 3-pole power supply was connected correctly to the 4 pin molex plug. But which floppy disk controller can supply the required +12V on line 1 and +5V on line 2 at the DC37 connector? I only know one floppy disk controller: the CompatiCard I or IV. The Megamate 2.8 is also powered by the CompatiCard IV.

CompatiCard DC power pins (P4)
CompatiCard DC power pins (P4)

Now everything was very simple. Put a new plug on the 34 pin cable, connect the drive to the CompatiCard IV (P4, straight cable, drive position 3) and that's it. The external 5.25 floppy disk drive works fine.

Very unspectacular, really. And here the wiring in detail.

TAXAN
DC37 connector to 34 pin floppy connector + power supply

Note: A floppy diskette drive with an old Shugart 34 interface may require a cable twist!

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