Teac FD-235GF 3156-u replacement

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Hi all,
I have an Advantest network analyser that uses a Teac FD-235GF 3156-U floppy
drive.  Teac cannot/willnot provide any information on the drive or a
suitable teac replacement. They tell me it's a proprietary drive and to
contact Advantest. Advantest won't help either, the analyser is past service
support life.

Anyone have a collection of NOS or even used FD-235GF 3156-U drives I can
buy ( want around 3-5)

Or - anyone have any info on the teac 235-gf apart from the teac.jp website
glossy and any knowledge of a suitable replacement?

If I can determine what the jumper settings mean perhaps I can find another
drive that would suit. Anyone have a copy of the service manual for the
drive that identifies the jumper settings?

The jumper configuration for the drive as installed in the 3762ah is per the
following list.
A1-B1,B4-C4,B3-C3,D4-E4, F1-G1
D1-D2, E2-E3, G3-G4

Any help appreciated


Re: Teac FD-235GF 3156-u replacement

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That could just be a standard PC floppy drive. Teac FD-235's are/used to
be used in IBM compatible PC's.  I'm sure I have some kicking around.
I'll have a look on Monday when I get into work.

Best Regards:

Re: Teac FD-235GF 3156-u replacement

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Hi Baron,
no problems.  Thanks for looking though.
I've had some success using a standard pc drive. Had to use DS0 rather than
DS1 (expected)  and needed to ensure the drive was using disk change on pin
34. The only thing that is still a little peculiar is the density select and
whether it's an input/output or both. Using a standard PC drive I need to
use a HD disk but cover over the HD hole and that seems to work reliably. On
the original drive I would use HD without covering up the hole. The only
issues I end up with is that the drive light is always 1/2 on when not in

I'll keep looking for FD-235GF data and playing around. i'ts almost sorted


Re: Teac FD-235GF 3156-u replacement
On Tue, 24 Feb 2009 17:43:49 +1100, "gcd"
and composed:

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This URL suggests that pin 2 is an input to the drive:

I suggest you look at the datasheet for an old multi-IO chip such as
were used on 486 and Pentium motherboards, before the functions were
incorporated into the chipset.

For example, here is the datasheet for a Winbond W83757F:

Amongst the FDC pins is RWC, Reduced Write Current. "This signal can
be used on two-speed disk drives to select the transfer rate."

 Logic 0 = 250 Kb/s
 Logic 1 = 500 Kb/s

It is described as an "open-drain output pin with 24 mA sink

I've seen this pin used in 2-speed 5.25" drives, but not in 3.5"
drives. It could be that the HD hole in the diskette tells the [PC]
drive what write current to use, but the drive does not report the
diskette type to the controller.

Does your Advantest network analyser write 1.44MB or 720KB of data to
the diskettes? It would seem odd if the drive were writing to the
diskette as if it were a 720KB lo-den type while the controller were
transferring data at a hi-den (500 Kb/s) rate.

Could it be that your current setup is operating at a 250Kb/s data
rate, and that your diskette's capacity is being reduced to 720KB?
Could it be that the original FDD uses the "RWC" pin as an output
rather than an input, and that it communicates the diskette type to
the analyser, in which case the analyser could automatically adjust
the data rate to suit??? In the latter case, if the analyser doesn't
get any feedback from the drive, perhaps it defaults to a lo-den data
rate. You might like to experiment with a pull-down or pullup resistor
on this pin.

- Franc Zabkar
Please remove one 'i' from my address when replying by email.

Re: Teac FD-235GF 3156-u replacement

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Hi Franc,
yes - pin 2 determines the density of the drive which is usally related to
the speed of the drive. Some fdc chips expect this to be sent to the dhip
from the drive, some expect to send it out to the drive and others are
bi-directional. Just depends on the age of the drive and the controller,  as
things changed from shugart to pc format interface.

This is why I'd like to get the jumper info - it would tell all.

I've had a bit of play with pull ups with no luck but I'll persist :)

Thanks for the links and suggestions, mind you, if all I end up with is a
light 1/2 on I can live with that - just need to ensure the configuration i
end up with is reliable in terms of data storage


Re: Teac FD-235GF 3156-u replacement
gcd Inscribed thus:
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DS1 (Drive Select) was the result of some bright spark realising that a
twist in the cable could be used to determine which drive was "A"  In
practice it probably saved a lot of money for the manufacturers and
confused techies !

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It sticks in my mind that it was always an output in the sense that it
was used to detect the difference between 720/144 Mb disks and set the
rotational speed, 300/360 rpm I belive.

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I wonder if that is anything to do with difference in the material used
for the magnetic coating.

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Best Reagrds:

Re: Teac FD-235GF 3156-u replacement
You might want to pose this question to the floppy hardware gurus at
"Individual Computers."

They make a product called the "Catweasel" which reads all floppy formats
known to man.  as such, they proabably have some experience with drives.


Or Tim Mann is also a floppy guru.

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