FLOPPY DRIVE REPLACEMENT GUIDE



     Many older synths use obsolete/expensive to find floppy drives. And they are notoriously unreliable of course so it's great to find a work around if possible right from the start rather than pouring money out the window. Some of the newer synths just use regular IBM compatible 1.44M floppy drives which are much more economical. So here are some helpful hints I'm accumulating to make it so we can go that direction OR towards various retros people have created. (Eg. see the Korg DSS-1 page.)

     Here is an article that has a lot of general tips.

HERE is a list of machine specific tips:

*Korg DSS-1 * Korg DSM-1 * SCI Prophet 2000, Ensoniq Mirage etc.





Korg DSS-1 - THe DSS-1 Uses a difficult to find 720K (DSDD) type floppy in ibm land anyway. Here is a clip from an article that may be helpful though the price is no longer what he said from what I see.

----------------- This may be common knowledge somewhere, but I never found it (and trust me, I've looked!) But if you need a floppy for your Korg DSS-1 (and possibly other old keyboards), and don't want to pay $60 for a replacement, read on.

At least i found that mitsumi D359M3 (not a very common drive) and the Teac 235HF (a very common drive you can get for $1.99 on ebay) work with the DSS-1. I didn't try others, but it's a very simple fix. Note that this is the 235*H*F; the standard 235F is rare and expensive, and is previously known to work with the DSS-1; the 235HF is common and cheap.

First of all, the DSS-1 needs to see DS0, not DS1. Some drives have jumpers (the teac I used has a jumper; switch the jumper from DS1 to DS0). Other drives don't; you can either do some complex soldering, or modify the floppy cable itself so that pins 10 and 12 are swapped (or at least pin 10 goes to where pin 12 used to; don't think it's usually necessary to go the other way).

The other thing you have to do is ground the RDY pin. Some drives (the chinon FZ-357 that's the usual substitute, but rare and expensive) have this; most don't. The RDY pin is on the connector. I don't remember how it's supposed to be hooked up, but grounding it makes it work for the DSS-1. Better yet, on the floppy interface, all even pins carry signal, all odd pins are ground - that's right, pin 33 is a ground. So all you need to do is bridge pins 34 and 33 on the floppy connector. You should be able to do this completely in the cable as well, if you don't want to modify the drive.

The above two modifications let me load a disk with a very common Teac 235HF. I imagine just about any drive would work with the above, and you don't even necessarily need to modify the drive; a cable can be modified instead.

Hope this helps someone. Glad to have my DSS-1 up and (mostly) working again! -----------------





Korg DSM-1- The general article I noted in the intro also talks about taking the Korg DSM-1 1.44M floppy and replacing it with a standard Samsung drive that is more modern. Go down quite a ways or..here I'll just archive the data in case it goes away :-)

Replacing old 3.5" drives with "new"

In Sept 2005, a customer wanted to replace a Hewlett Packard 3.5" drive (9122C), made by Sony (MP-F73W-50), with a modern PC Windows Pentium 3.5" drive by Samsung. The old drive replaced some ground signals with power and did not use a seperate power connector. He compiled the following list of signals, and wired an adapter accordingly. He also purchased from me a set of Sony documents for the MP-F73W-00D and 01D drives. An image of his Sony MP-F73W-50 drive is at this link. He says:

"The following data is a combined chart of the data from the HP manual and data from a pdf file for a new Sony drive #MPF920-Z. Use a fixed-width font to view it:

Pin#  Signal (Old Sony)  Signal (New Sony)  Pin#  Signal (Old Sony)        Signal (New Sony)
1     Disc Change Reset   NC                2     Disc Change Indicator    NC
3     +5V                 Key               4     Density Bit              NC
5     +5V                 Ground            6     Drive Select             NC
7     +5V                 Ground            8     Index Pulse              Index
9     +5V                 Ground            10    Drive Select 0           NC
11    +5V                 Ground            12    Drive Select 1           Drive Select 1
13    Ground              Ground            14    Drive Select 2           NC
15    Ground              Ground            16    Motor On                 Motor On
17    Ground              Ground            18    Direction Select         Direction
19    Ground              Ground            20    Step                     Step
21    Ground              Ground            22    Write Data               Write Data
23    Ground              Ground            24    Write Gate               Write Gate
25    Ground              Ground            26    Track 0 Indicator        Track 00
27    Ground              Ground            28    Write Protect Indicator  Write Protect
29    +12V                Ground            30    Read Data                Read Data
31    +12V                Ground            32    Head Select              Head 1 Select
33    +12V                Ground            34    Ready                    Disc Change

(note: "new Sony" corresponds to other 3.5" drive pinouts as well. - Herb)

"I made an adapter to reroute the various pins, and installed a brand new Samsung FBT6 floppy in the HP drive using the adapter, but things are not quite there yet. I will get the scope going to see how things behave with the old drives vs. the new drives. I'm sure I'll figure out the differences and get things going."

"One observation: The p.c. board layout...for the MP-F73W-00D and 01D drives is very similar to the layout of my Sony MFD-73W-50 drives. [Docs show] that the odd row of the 34-position connector, which usually has all of its pins connected to ground (except pin #1 in the "00D" version), is actually divided into three sections, just like my Sony MFD-73W-50 drives. The pin assignments for the 34-position connector as shown on page 3-1 show that the entire odd row is the "return" (ground) connection (pin #1 of the "00D" drive is the DISK CHANGE RESET" pin), but you can see on the layout that the three sections of the odd row can be tied together or kept separate by using or deleting jumpers RJ1 and RJ2. On my Sony MFD-73W-50 drive, pins 3, 5, 7, 9 and 11 are kept separate (RJ1 deleted) and are used for the +12V supply connection, while pins 29, 31 and 33 are kept separate (RJ2 deleted) and used for the +5V supply connection. Pins #13, 15, 17, 19, 21, 23, 25, and 27 are ground. All of these drive models have a place on the p.c. board for a standard 4-position power connector, but in the MFD-73W-50, that connector is not installed on the p.c. board. Instead, the +5V supply is routed from pins 29, 31 and 33 of the 34-position connector to pin #4 of the standard 4-position power connector by adding JP4, and the +12V supply is routed from pins 3, 5, 7, 9 and 11 of the 34-position connector to pin #1 of the standard 4-position power connector by adding JP3."

Herb commented:

>> I noticed the old SONY drive has a "density select" line. I suggest 
>> you look closely at how the old drive performs a "density" change. New 
>> drives are a lot smarter than the old drives, and new drives may make 
>> this change automatically and in a number of ways. One thing some 
>> modern drives AND SYSTEMS do is not change motor speed, but change the 
>> BIT RATE of data going to the drive."

"Regarding the "density select," I have that on my list of things to consider. I tried a 720k disc in the new drive and got it to perform a directory listing, which it would not do with a 1.44M disc. But it got temperamental again after that. Lots to check. Disc Change Reset (pin #1 on the old Sony, NC on the new Sony), Disc Change Indicator (pin #2 on the old Sony, NC on the new Sony), etc., are things I will look at. But I'm using a new Samsung drive, and it may be doing things a bit differently too. It has deleted most of the ground pins on the connector, apparently because they are redundant and they can save a penny or two." 





Prophet 2000 etc. -

Here is a note from Dan Wilson containing information he archived from a now removed site

This might have been the list you had on compatible replacement P2000/2002 drives....
----
Apparently these replacements can be used (although i have not verified this):

Toshiba FDD4216G0K
Sony MP-F53W-00D
Cannon MD-350
Jumper Settings: (1) Jumper on "SO" (2) Jumper on "AH"
(These "jumper positions" are located on the top right-hand corner of the drive... with the drive face plate facing you.)
Sony 63W
TEAC FD-235HF
SONY MT-2 1-623-457-14
SONY MPF520-1 (jumper needs to be in inner position)
EPSON SMD-400 (jumpers across DC, MC and C0)
PANASONIC JU-257A694P (Jumper Settings: (1) SW1 (set to DC) (2) SW2 (set to "OUT") (3) SW3 (set to "zero") (4) SW5 (set to "P2") (5) SW6 (set to "MS"))
--------

I personally have had the best luck with the old 3/4 height TEACs - same with the Ensoniq Mirage and Buchla 400.

..that said - fitting a superb Lotharek Rev.F HxC virtual floppy is by far the neatest solution on the P2002, S900, EMAX I, Emulator II, Synergy II+ / Kaypro II combo etc....  (See Lotharek HxC VF product

I have made disk images for many systems now to get you started if you ever take that route.

All the best,

Dan.