Visitor with a floppy mod question (Chinon).

I hope you guys don't mind a non-Amiga user popping in here with a question, but it seems to be the place with the most knowledgeable on the workings of these old floppies. I'll try to keep it as brief as I can.

I've got a musical sampler here which uses one of those Chinon FZ-357 things you guys use. It's supposed to handle HD as well as DD disks. The drive didn't act right when I got the machine (used). It refused to read any of my older DD library disks and was kind of hit-or-miss on everything else. It also had a faint glow on the LED when it was idle, which seems to occur on a non-Chinon I tried too, so I can't rule out a controller problem, but I'm guessing it's the drive.

I realize your Amiga drive specs are slightly different, but I wondered if anyone here might know what I'm needing to change to meet the requirements on my machine. I've got a handful of old 3.5" drives: a Panasonic JU-256A868PC (PCB looks just like the JU-256a88p picture on page 14 here),a Citizen Z1DE-58A,an NEC FD1231M, and a Samsung SFD-321B.

The original Chinon FZ-357 had the following config: DS0,MM,and DC jumped (nothing else)

The Samsung was the first I tried as it had decent labeling. DC was already jumped and I changed the ID to DS0, but I'm not sure what its equivalent of that MM motor setting is. Under those settings, the motor never seems to start. It also doesn't check for a floppy until after it's scanned all SCSI IDs. With the Chinon, the drive comes to life shortly after the unit powers up and the OS gets loaded from floppy. I noticed I could spin the motor up briefly by bridging the RDY points, but that jumper wasn't even set on the Chinon.

Is there any hardwired default function of the FZ-357 which I need to replicate with jumpers or mods on this drive?

Any help would be appreciated, and I'll let other sampler owners know if I can get anything going. We can get ripped off pretty badly on replacements.

Thanks!

PS- The Samsung PCB looks to be identical to Grega's back on page 14, though mine is a Rev WT-04 rather than 05.

[Arnie]

I think that the fz357 you use is a PC drive. The ones that Amigas use share the same name but are different in the fact that they slow the drive spin down to 150 to read HD disks. DD disks are read at 300.

You can tell the difference by the jumpers on the rear. Amiga drives have a smaller jumper block 3x2 rows of jumper pins on the rear, PC drives 7x2.

Originally Posted by Arnie

Amiga drives have a smaller jumper block 3x2 rows of jumper pins on the rear, PC drives 7x2.

Thanks Arnie!

Yeah, it's definitely 7x2. Do you know what it is exactly which differentiates standard PC drives from this version of the Chinon though? Is there anything other than the external jumpers which might tell me what it's set up for? All of those others are probably from Pentium4 era PCs and none of them even attempt to work in the sampler.

Take Care

[kneehighspy]

and the amiga version part number is fz-357a, and i would love to have one of the little buggers myself. the drive mods you mentioned do work to a varying degree, i have done a couple, but the drives still will not support hd disks.

If it tells anybody anything, I had a diagram from the service manual showing the sampler's floppy pinout. It seems to follow the Shugart pinout with the exception of pin 2 being labeled "MODE" on the sampler, rather than Disk Change Detect (not sure if that means the same thing).

That Samsung SFD-321B looks to follow the Shugart as well, so I guess it's down to the config jumper pads??

Thanks Again

[idrougge]

Usually it's a case of swapping pins 2 and 34.

Thanks idrougge,

I tried the jumper wire I see in pictures here, taking the line from the controller IC to pin 2, rather than going through the jumper to pin 34. It definitely changes something for the better, but in order for it to work, I also have to jump across the original DC jumper pads, so the IC signal is now connected to pin 2 AND pin 34. Am I supposed to do a full swap and cut the trace headed to pin 2 and redirect that one to 34? I don't see that in the SF-321B mod picture, but I know you guys also don't usually have DC jumped like we do.

Other notable issue is that once it detects a disk and begins reading, the read time is insanely slow. It takes several minutes to load the OS from a 720k floppy, which I believe only takes up a portion of the disk.

I'll attach a picture of the original (Chinon) PCB if anyone can tell anything from that.

Much thanks again!

I went ahead and cut that trace to pin 2 and jumped it over to 34 (so the two lines were completely swapped). It would boot and attempt to load the floppy, but fail with an invalid system disk error.

I put the DC jumper back while the two lines are still swapped, so it's like I did before, with both 2 & 34, and their original destinations all connected as one. It loads, but is way way way slow.

Thanks

<UPDATE EDIT> The speed thing is possibly related to the utilities used to read/write Roland data to floppies on the PC. While the PC utilities can write to this oddball floppy format, there appears to be some difference between a disk formatted as Roland by the PC, and one done by the actual sampler. I'm still getting a lot of R/W errors with various floppies, but they're all old as hell and I'm really not even sure about the history of this Samsung.

PS- Is there a document or picture somewhere which describes the functions of the various jumper points on a Chinon FZ-357 PCB? I've seen people here suggest closing different ones for Amiga use. (I realize there's more than one version, but any of them might be helpful) -Thanks

[idrougge]

My brother also had a Roland sampler. It failed to boot because of a too weak power supply.

They're nice when they're working, but I guess all that stuff's getting old now. I spent a couple years on this one's predecessor (S-550) back when it was current, and was using it all night every night. I think it may have crashed or misbehaved once or twice tops. They've also got mouse input and monitor out, which is still pretty high tech for a sampler.

Take Care

[glenn]

Originally Posted by kneehighspy

and the amiga version part number is fz-357a, and i would love to have one of the little buggers myself. the drive mods you mentioned do work to a varying degree, i have done a couple, but the drives still will not support hd disks.

No, you have to swap one of the PCB's, back in the time when it was easy to find FZ-357 in PC's I repaired FZ-357A by swapping the card into the "new drive" a few times.

I think there was another drive than the FZ-357 that could be used as a donor too.

[LSone]

Just spent my evening modifying a JU-256A868PC drive.. didn't match the pictures... didn't match on the main IC pn.. even the traces were a bit off.. but in the end it still worked.. let me know if anyone wants pictures.

I did also convince myself that masking off the HD hole with tape is important. Maybe I've become superstitious since i didn't think that mattered before but there it is. Block the hole.

[Jope]

It does affect the operation of the drive. Better block it off or tape your HD disks if you can't find DDs anywhere.