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Epson SD-600 5.25" floppy drive - problems, and about jumpers

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giobbi

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Hi all,

I've recently got three Epson SD-600 5.25" floppy drive: one is surely broken, one that doesn't read the disks, and the third one seems to work, more or less. I will start to talk about this third one.

(btw I'm testing them in a Ms-Dos 6.22 environment)

In first, it works as B: but not as A:. I tried to swap it from B: to A: with a blind change into the jumper bank (SS1 from 1 to 0, see below the jumper table) and now it's checked at boot as A: drive (of course, bios was set accordingly) but if I ask a DIR when it's set as B:, it works; same thing when it's set as drive A:, I got a general failure on drive A: -- of course with the same floppy disk inserted. Maybe, in order to change it from B: to A: there's more to change into the jumper banks..?
However I switched it to B: again.

Another issue: I can't format a floppy. I tried many floppy that *seemed* to work (since they're old floppies, I can't be sure they are really good). I always get an error about invalid 0 track, bad disk. Any disk content is erased during this attempt to format.
I tried in the following ways (default, it tries to format 360k):
format b: /u /F:1.2
format b: /u /F:360
format b: /u /F:180
format b: /u /4
format b: /u
format b:

Honestly I don't remember how I used to format 5.25" floppy disk, I believe the last one I formatted was in the beginning / middle of '1990s... ^_^

----------------------------------------
About the unit that doesn't read the disks: the disk spins, the heads move, but I get a seek error reading drive B:.
----------------------------------------


Now, this kind of drive has six jumper banks, so I'm trying to understand their meaning. I'm copying below the jumpers scheme:

SS1 - options: 0 - 1 (ON) - 2 (off) - 3 (off)
SS2 - options: DA - HL - RA : missing jumper bank (no jumper on the PCB)
SS3 - options: D / S (set to S)
SS4 - options: MH/ML (set to ML)
SS5 - options: RC (off) - DC (ON)
SS6 - options: S1 (ON) - S2 (ON) - S3 (off)


The questions for you are the following ones:

1) Do you know if I'm going wrong formatting, or is there anything I can try / clean / lube / check / etc. in order to solve that issue?

2) Have you any clue about what every jumper bank means? I also wish to find a way at least to swap it from B: to A:

3) What about the seek error on the drive that doesn't read the disks?

4) Any other clue about old floppy disk drive care, cleaning and refurbishing are welcome!

thank you

Giobbi
 
Thank you,

I found a similar Epson floppy on this manual; however it doesn't explain all the jumpers.
I will try to find some explanations looking at the jumpers code...
 
Could you describe the complete system that the floppy is attached to, especially floppy controller and BIOS version?

Have you done any formatting of the floppy with the /U switch?
 
In first, it works as B: but not as A:. I tried to swap it from B: to A: with a blind change into the jumper bank (SS1 from 1 to 0, see below the jumper table) and now it's checked at boot as A: drive (of course, bios was set accordingly) but if I ask a DIR when it's set as B:, it works; same thing when it's set as drive A:, I got a general failure on drive A: -- of course with the same floppy disk inserted. Maybe, in order to change it from B: to A: there's more to change into the jumper banks..?
Are you aware that in the IBM PC and the vast majority of clone computers, that:

1. CABLE

A special cable is used, one with a particular twist in it.
A diagram is at [here].
A photo is at [here]

2. DRIVE-SELECT JUMPERS

With the above cable, both floppy drives are set to the second drive select position.
A: is the floppy drive at the end of the cable (after the twist).
B: is the floppy drive in the middle of the cable (before the twist).
 
giobbi,
I'm thinking your problem stems from the TWO Jumpers on SS1.

SS1 is a the Drive Select Jumpers and are two pins, WITH jumper or NO Jumper. There are 4 sets of two pins typically marked "0", "1", "2", & "3"
ONLY ONE JUMPER should be selected. The Drive should be set for DS0, or DS1, or DS2, or DS3. Most times this will depend on the actual
position of the connector on the Floppy Cable (from the Floppy Disk Controller), and whether the Cable has the infamous Pins 10-16 Twist, and
can also depend on, if the LAST FLOPPY on the Cable requires a TERMINATOR Resistor (or NOT USING a TERMINATOR Resistor)

I've attached a Typical Interface PNG file of the Floppy Disk Controller Signals. (There is Radio Shack Model 4 Info on the PNG, just disreguard it)

FDC.jpg

Now, taking a different approach to the CONTROL SIGNALS to the Drive from the Floppy Disk Controller (FDC) lets chase the CONTROL Pin Wiring
that you might possible have the capability of selecting with JUMPERS on a Floppy Drive.

Those Pins are:
Drive Select (ONLY One of the following should be selected)
Pin 10 -- Drive Select 0
Pin 12 -- Drive Select 1
Pin 14 -- Drive Select 2
Pin 6 -- Drive Select 3

There are some Pins that may/can have multiple functions. Those Pins are:
Pin 2 -- TYPICALLY -- 0=Double/1=High Density
Pin 4 -- TYPICALLY -- No Connection
Pin 34 -- TYPICALLY -- Disk Change/Ready

So, Disk Change (DC) OR Ready (RY) can be routed to Pin 34 by Jumpers, but DC can also be routed to Pin 2, if the Drive has that
OPTION (typically named DC2 Jumper).

Likewise, Pin 2 (Density) can be selected automatically by the Floppy Drive, or it can be set by a (HIGH/LOW) on Pin 2, or the Floppy
Drive can be JUMPERED to have the HD OUTPUT be routed to Pin 2 (ONLY on Specific Floppy Drives)

A Floppy such as the Teac FD-235F, HF - 3XXX Series has such options.

FD1.jpg


Another Possible JUMPER that is TYPICAL for Floppy Drives is one labeled MO or MS.
MO is "Spindle Motor Controlled by Motor On Signal, which is Pin 16".
MS is "Spindle Motor Controlled by Drive Select Signal, which could be One of four possibilities".

Another possibility is a HM Jumper.
HM is "Head Load with Motor ON".

I haven't a clue as to the other Jumpers on your Epson Floppy.

Thanks.

Larry
 
Last edited:
Hi Larry,

giobbi,
I'm thinking your problem stems from the TWO Jumpers on SS1.

SS1 is a the Drive Select Jumpers and are two pins, WITH jumper or NO Jumper. There are 4 sets of two pins typically marked "0", "1", "2", & "3"
ONLY ONE JUMPER should be selected. The Drive should be set for DS0, or DS1, or DS2, or DS3. Most times this will depend on the actual
position of the connector on the Floppy Cable (from the Floppy Disk Controller), and whether the Cable has the infamous Pins 10-16 Twist, and
can also depend on, if the LAST FLOPPY on the Cable requires a TERMINATOR Resistor (or NOT USING a TERMINATOR Resistor)

I'm getting a really strange behavior with the SS1 jumper. I believed it was enough to set the SS1 jumper from "1" (2nd position) to "0" (1st position), change the bios setting from
Floppy A = none - Floppy B = 1.2 Mb to Floppy A = 1.2 Mb - Floppy B = none. I have a straight cable (not a crossing one) with 1 connector for 3.5" floppy and one for 5.25" floppy.

Now, talking about the good floppy I have: it works fine as B: unit (SS1 = 1) but it doesn't work as !: unit (SS1 = 0). It is called by the motherboard in some way but it doesn't work: i.e. using a simple DIR command, the front LED goes on but there's no activity from the floppy drive. After few seconds I get the message "not ready reading Drive A - Abort/Retry/Fail"
Also at boot it's invoked but the only response from it is the green led.

Now, taking a different approach to the CONTROL SIGNALS to the Drive from the Floppy Disk Controller (FDC) lets chase the CONTROL Pin Wiring
that you might possible have the capability of selecting with JUMPERS on a Floppy Drive.

Smart approach, I didn't think at it :)

So, Disk Change (DC) OR Ready (RY) can be routed to Pin 34 by Jumpers, but DC can also be routed to Pin 2, if the Drive has that
OPTION (typically named DC2 Jumper).

I have a similar jumper, RC / DC I suppose it's the same (it's set as DC). But what does it mean?

Another possibility is a HM Jumper.
HM is "Head Load with Motor ON".

I have a MH / ML (set on MH as default) that could be the same jumper. But what does it mean this setting?

Thank you for you help!

Giovi
 
Could you describe the complete system that the floppy is attached to, especially floppy controller and BIOS version?

Have you done any formatting of the floppy with the /U switch?

hm, I'm testing it one a relatively (if compared to the floppy age!) new motherboard, with a P300 Cyrix CPU (labeled as IBM).

Yes I tried the /U parameter (you can see all the test I did above). However I did some steps ahead.
I tried the Format Master software and with some adjustment to the heads alignment (I mean: aligning the 0 head to the 1 head - the 0 head was a little out of alignment if compared with its opposite) I got a working floppy. I can format, verify the disk, do a SYS B: command, etc.

I suspect it's out of alignment (it won't probably read a floppy disk from another drive), but for the moment I will not investigate in that direction.
 
Are you aware that in the IBM PC and the vast majority of clone computers, that:

1. CABLE

A special cable is used, one with a particular twist in it.
A diagram is at [here].
A photo is at [here]

2. DRIVE-SELECT JUMPERS

With the above cable, both floppy drives are set to the second drive select position.
A: is the floppy drive at the end of the cable (after the twist).
B: is the floppy drive in the middle of the cable (before the twist).

Yep, unfortunately I'm old enough to remember that part ^_^
However, if I'm right, the twist simply swap the unit from B: to A: and from A: to B:, so when you bought a spare disk (usually configured as B: from factory) you can replace your A: drive putting it on the twist side, or add a B: drive putting it before the twist. But this information was saved on a 30 years old tape in my mind ;-) so I'm not sure about that.

I have a straight cable, one connector for 3.5" and one for 5.25". So a B: drive will be a B: drive until you change the right jumper.... right? Or wrong?
 
In the IBM PC convention, all drives are set to DS1 (the second select). The twist in the cable swaps around motor and drive selects. You cannot accomplish the same thing with a straight cable and change in drive-select jumper. You need the twist to get a drive to operate as "A". If you change drive select from 1 to 0, you still have the issue of the motor control line.
 
In the IBM PC convention, all drives are set to DS1 (the second select). The twist in the cable swaps around motor and drive selects. You cannot accomplish the same thing with a straight cable and change in drive-select jumper. You need the twist to get a drive to operate as "A". If you change drive select from 1 to 0, you still have the issue of the motor control line.

thank you, now it's clear!
 
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