Pc to Amiga floppy drive mods - My unreleased schematic for CHINON FG-357

[Marty_McFly]

Hi guys,
Hoping that this topic could be of use for all those that are interested in PC to Amiga floppy drives' mods, below is my experience and successfull modification.

I wish to outline that there are no mods for this specific drive online. At least I looked for around one week among dozens of Google results and I did not find a schematic but only topics with requests for schematics for this PC floppy drive.

Notwithstanding this, the mod is quite fast to make, please see the pics and instructions below:



1) Swap the links between PIN 2 and 34, cutting the original tracks on the PCB and swapping the paths with the aid of 2 wires.
For a more "gentle and clean" solution, you could avoid the cuts on the PCB preferring a direct modification of the IDE CABLE used to connect the floppy drive to the Amiga PCB (swapping the wires of pin 2 and 34 of IDE CABLE, ie: cutting PIN 2 wire in the middle and resoldering with the PIN 34 cutted wire and viceversa).

2) After the above, you must solder (closing the circuit) the points JP1 and JP3 (see red arrows). Assuming that in the original PC drive JP4 and JP5 are already soldered.
In any case you must not solder JP2 or the ready signal will be disabled. I outline this because in some topic related to this drive, some user suggested to try soldering also JP2 but without any result.



3) In any case the real nightmare of this drive is the lack of reference for the jumpers settings. On one side of the drive there are 12 pins to close and open with jumpers.
I tried several attemps and the one working with df0 (enabling the full working of drive as DS0 signal) is with the use of only one jumper setted as below.




Consider that in the original jumpers configuration for PC use, are involved 3 jumpers.




On the original/native Chinon drives for Amiga are involved at least 3 or 4 jumpers for the correct setting as DF0, DF1, DF2 etc.... so the resulting configuration of this mod is quite strange.

And at the same time is strange that on the metal case of the drive there is no embossed schematic of jumpers for PC (that could be of use for Amiga conversion as well). No reference out, nor inside the drive.




As last touch, I disabled the HD check, wiring the two external pins (see green numbers 1 and 3 in the picture) of the switch/sensor for HD floppies.





The unique heavy problem of this mod is when I try to plug and use external drives. The mod above automatically disable any df1 drives plugged to Amiga, whatever is the position of the other jumpers.
If I try to add more jumpers to the 12 pins I have no positive outcome, so this drive with the mod above can be used currently only as standalone Df0 drive inside Amiga, because external drives also if correctly setted, remain disabled and not showed/recognized from the system. They disappear in WB, are invisible as drives, I do not see errors like "DF1 BAD", "NDOS" etc. The units result as not plugged.

Anyway on the opposite side of this drive there are 4 pins as well, but I do not have idea of their use. They are probably part of a connector for some other function.
Although they are not part of the dive power connector (the latter is near the IDE connector).




It would be usefull and appreciated if someone could post a schematic of the jumpers combinations for the 12 pins on the drive's side. Or alternatively if there is some other soldering to make based on other PC models, just to unlock and recognize the external drives.

Any of you can help me about this problem? Or where I have to look to resolve the problem of the invisible external drive?



I would like to give priority to this drive for my Amigas because a such mod as above is less forced that a mod to an ALPS, SONY etc.