Floppy drive motor moving too slow?

Firestone · 12 February 2014, 22:14

Got a problem with one of my floppy disk drives in my A4000.
It's a Chinon FZ-357A.

Problem is that it seems like the motor that is spinning the disk is moving too slow. I have compared it to a similar drive, and the difference is quite noticeable.

Tonight I disassembled the drive completely to have a look at the boards, and it's possible that some of the capacitors may have been leaking and is defective.

But there is one component on the board that I'm wondering about... To me it looks like a fuse, but it's hard to read whats written on it. I think it's "4.00 MF" or something.
Take a look at the picture below: (XTAL1)

Is this a 4.00 Mili Farad capacitor, or what is it?

There seems to be some corrosion on it.

Loedown · 13 February 2014, 00:09

Xtal1 = Crystal 1

If you put a high density floppy in for testing then yes they spin at half speed.

demolition · 13 February 2014, 00:44

Indeed, so if it spins slow with DD disks, check the DD/HD switch.

pandy71 · 13 February 2014, 08:04

Slight OT - sorry for that - i see that there is 7474 on board - seem that HD Amiga drives use additional divider by 2 to achieve 150 RPM - is there anywhere available schematics for Chinon FZ-357A?

And i would check HD switch (like demolition says) - perhaps it is corrupted and signaling constantly HD mode i.e. 150 instead 300 RPM

Amiga1992 · 13 February 2014, 13:56

I would clean the motor spindle thoroughly and lubricate it.

ElectroBlaster · 14 February 2014, 14:42

Im no expert but I would look closely at the capacitors! If they have dull solder pads and the area around them looks a little greasy. You may suddenly get "DF0: ???" for no reason which seems to be the first outright sign something is awol.

I have personally fixed one drive with that problem. Spurred on by somebody on this forum who fixed 3 of their own drives. Dam capacitors seem to be everywhere these days! Even the tiny one's that I was led to believe are no problem.

I have a handfull of Chinon FB's here. Two are in a mess and need working on.
I stupidly sold an HD version a while back! If I had it, I would have opened her up and took some detailed pictures.

Firestone · 15 February 2014, 00:10

Thanks everyone!

Of course the slow spinning is caused by the drive beeing av HD-drive! I completely forgot that this drive was a HD-drive!

Thanks for noticing!

The motor spinns at "normal" speed when a DD-disk is inserted.
So far so good...

Well.... so today I reassembled the drive, but the sympthoms are the same. Just those three clicks and kickstart screen gets back. (Sound of empty disk).

In my closet I found an old Chinon FZ-357 drive pulled from an old PC.
I opened it and found out that the heads seemed to be the same. So I switched them, but the same problem appears.

Of course, I could modify the drive from the PC to be used as a 880k drive in the Amiga, but it would be cool to get the HD-feature too

I guess there could be a capacitor problem here.... (?)

EDIT:
Reassembled the drive again with the old head again now, and just for fun I tried it, and now it works (?!!). The heads must have got misaligned or something.....

Thanks everyone for helping
Cheers!

pandy71 · 15 February 2014, 16:35

Issue with PC drives is that they can have different head, write amplifeir, different timing on reading channel etc - Amiga HD is DD that spin twice slower, PC HD is HD where transfer speed is twice faster to Amiga...

Still not sure how mechanically different is spindle motor for Amiga HD - at least for 150RPM torque expected to produced by normal PC spindle motor can be lower or even to low to revolve in reliable way.
It will be nice to have schematics for both versions or at least good quality pictures for both Chinon versions...

Firestone · 15 February 2014, 17:03

I'm into this question too Pandy...
As far as I can see several people have tried to get more information on how to convert standard PC-drives to HD-floppydrives compatible with the Amiga.

Googled differences between the Chinon FZ-357 and FZ-357A and some people says that you're out of luck if the board with the spindle is different than the FZ-357.
And if the board is the same, you are still only able to convert it to a standard 880k drive.

There are probably very few floppydrive-models available as a HD-drive for the Amiga.
I can't remember exactly, but was the A4000 the only model with HD-floppydrives as standard?

Have searched for schematics for the Chinon-drives, but can't find any.

I'm thinking that the drive would be less reliable when writing data at half speed too... Could be comparable to old VCRs where you had this LP (longplay) function that would slow down the tape, and you would get more on every tape, but in the cost of quality.
Not quite the same with floppydrives but.......I guess you get my point....

Loedown · 15 February 2014, 22:05

Quote:

Originally Posted by pandy71

Issue with PC drives is that they can have different head, write amplifeir, different timing on reading channel etc - Amiga HD is DD that spin twice slower, PC HD is HD where transfer speed is twice faster to Amiga...

Still not sure how mechanically different is spindle motor for Amiga HD - at least for 150RPM torque expected to produced by normal PC spindle motor can be lower or even to low to revolve in reliable way.
It will be nice to have schematics for both versions or at least good quality pictures for both Chinon versions...

I have both a FB-357A and FB-354 here, I can take some hi-res shots if you like. Highlight what you want to be able to see.

prowler · 15 February 2014, 23:05

Quote:

Originally Posted by Firestone

As far as I can see several people have tried to get more information on how to convert standard PC-drives to HD-floppydrives compatible with the Amiga.

This is a Sony MPF920-E/131 floppy drive unit which has been converted to operate at 150rpm in high density mode for compatibility with the Amiga.

As you can see, it is not trivial. The key to the conversion is the addition of the PLCC chip, which has been glued to the chassis top-down on the right side of the picture.

A high quality high density floppy drive unit with a diecast chassis is required for this conversion to work. The Sony MPF920-E is one such drive.

Amiga_CDTV · 15 February 2014, 23:29

prowler: whoah, that's so cool. Are there instructions for this mod? I got a couple of this exact model of drives (saved from a lot of recycle-going PCs), I have already coverted two to DD Amiga drives. I would love to test this HD mod on one of those drives. Also nice to know that these are drives of good quality.

prowler · 15 February 2014, 23:40

Quote:

Originally Posted by Amiga_CDTV

prowler: whoah, that's so cool. Are there instructions for this mod?

I'm afraid I have no details for that modification, as the drive had already been modified when I bought it (from fitzsteve).

Here is a link to my original post about this drive. See also fitzsteve's reply three posts later.

hese · 15 February 2014, 23:51

It's a MicroniK Power M-Disk HD drive with custom GAL code. And the GAL chip is most likely read protected so no duplication is possible.

pandy71 · 16 February 2014, 02:07

Quote:

Originally Posted by prowler

As you can see, it is not trivial.

This is my point on 357A there is 7412 and 7474 thus seem that overall conversion is not so hightech - i have even idea how it works but i be delighted to see schematics or at least hires photos for PCB.

Loedown · 16 February 2014, 02:10

Quote:

Originally Posted by pandy71

This is my point on 357A there is 7412 and 7474 thus seem that overall conversion is not so hightech - i have even idea how it works but i be delighted to see schematics or at least hires photos for PCB.

What do you want highlighted in the pictures Pandy71?

pandy71 · 16 February 2014, 14:10

Quote:

Originally Posted by Loedown

What do you want highlighted in the pictures Pandy71?

Perhaps to recreate schematics - really curious that's all.
Need to open my 3000 then...

Loedown · 16 February 2014, 14:18

Quote:

Originally Posted by Loedown

What do you want highlighted in the pictures Pandy71?

What, not why. I will try to grab a few hi res pics tomorrow after I have finished my chores.

pandy71 · 18 February 2014, 00:18

Quote:

Originally Posted by Loedown

What, not why. I will try to grab a few hi res pics tomorrow after I have finished my chores.

sorry - my fault, i was to quick - most interesting is motor PCB - i want to compare 357 vs 357A ( i assume added circuitry will be responsible for RDY line pattern for DriveID - different for DD and different for HD or perhaps depend from inserted floppy? and for dividing clock by 2 i.e. 4MHz to 2MHz).

Loedown · 18 February 2014, 06:41

12 February 2014, 22:14	#1
Firestone Registered User Join Date: Apr 2013 Location: Norway Posts: 249	Floppy drive motor moving too slow? Got a problem with one of my floppy disk drives in my A4000. It's a Chinon FZ-357A. Problem is that it seems like the motor that is spinning the disk is moving too slow. I have compared it to a similar drive, and the difference is quite noticeable. Tonight I disassembled the drive completely to have a look at the boards, and it's possible that some of the capacitors may have been leaking and is defective. But there is one component on the board that I'm wondering about... To me it looks like a fuse, but it's hard to read whats written on it. I think it's "4.00 MF" or something. Take a look at the picture below: (XTAL1) Is this a 4.00 Mili Farad capacitor, or what is it? There seems to be some corrosion on it.

15 February 2014, 00:10	#7
Firestone Registered User Join Date: Apr 2013 Location: Norway Posts: 249	Thanks everyone! Of course the slow spinning is caused by the drive beeing av HD-drive! I completely forgot that this drive was a HD-drive! Thanks for noticing! The motor spinns at "normal" speed when a DD-disk is inserted. So far so good... Well.... so today I reassembled the drive, but the sympthoms are the same. Just those three clicks and kickstart screen gets back. (Sound of empty disk). In my closet I found an old Chinon FZ-357 drive pulled from an old PC. I opened it and found out that the heads seemed to be the same. So I switched them, but the same problem appears. Of course, I could modify the drive from the PC to be used as a 880k drive in the Amiga, but it would be cool to get the HD-feature too I guess there could be a capacitor problem here.... (?) EDIT: Reassembled the drive again with the old head again now, and just for fun I tried it, and now it works (?!!). The heads must have got misaligned or something..... Thanks everyone for helping Cheers! Last edited by Firestone; 15 February 2014 at 01:14.

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13 February 2014, 00:09	#2
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946	Xtal1 = Crystal 1 If you put a high density floppy in for testing then yes they spin at half speed.

13 February 2014, 00:44	#3
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	Indeed, so if it spins slow with DD disks, check the DD/HD switch.

13 February 2014, 08:04	#4
pandy71 Registered User Join Date: Jun 2010 Location: PL? Posts: 2,778	Slight OT - sorry for that - i see that there is 7474 on board - seem that HD Amiga drives use additional divider by 2 to achieve 150 RPM - is there anywhere available schematics for Chinon FZ-357A? And i would check HD switch (like demolition says) - perhaps it is corrupted and signaling constantly HD mode i.e. 150 instead 300 RPM

13 February 2014, 13:56	#5
Amiga1992 Registered User Join Date: May 2001 Location: ? Posts: 19,646	I would clean the motor spindle thoroughly and lubricate it.

14 February 2014, 14:42	#6
ElectroBlaster Junior Member Join Date: Mar 2002 Location: Exeter, Devon, UK Age: 49 Posts: 1,708	Im no expert but I would look closely at the capacitors! If they have dull solder pads and the area around them looks a little greasy. You may suddenly get "DF0: ???" for no reason which seems to be the first outright sign something is awol. I have personally fixed one drive with that problem. Spurred on by somebody on this forum who fixed 3 of their own drives. Dam capacitors seem to be everywhere these days! Even the tiny one's that I was led to believe are no problem. I have a handfull of Chinon FB's here. Two are in a mess and need working on. I stupidly sold an HD version a while back! If I had it, I would have opened her up and took some detailed pictures.

15 February 2014, 16:35	#8
pandy71 Registered User Join Date: Jun 2010 Location: PL? Posts: 2,778	Issue with PC drives is that they can have different head, write amplifeir, different timing on reading channel etc - Amiga HD is DD that spin twice slower, PC HD is HD where transfer speed is twice faster to Amiga... Still not sure how mechanically different is spindle motor for Amiga HD - at least for 150RPM torque expected to produced by normal PC spindle motor can be lower or even to low to revolve in reliable way. It will be nice to have schematics for both versions or at least good quality pictures for both Chinon versions...

15 February 2014, 17:03	#9
Firestone Registered User Join Date: Apr 2013 Location: Norway Posts: 249	I'm into this question too Pandy... As far as I can see several people have tried to get more information on how to convert standard PC-drives to HD-floppydrives compatible with the Amiga. Googled differences between the Chinon FZ-357 and FZ-357A and some people says that you're out of luck if the board with the spindle is different than the FZ-357. And if the board is the same, you are still only able to convert it to a standard 880k drive. There are probably very few floppydrive-models available as a HD-drive for the Amiga. I can't remember exactly, but was the A4000 the only model with HD-floppydrives as standard? Have searched for schematics for the Chinon-drives, but can't find any. I'm thinking that the drive would be less reliable when writing data at half speed too... Could be comparable to old VCRs where you had this LP (longplay) function that would slow down the tape, and you would get more on every tape, but in the cost of quality. Not quite the same with floppydrives but.......I guess you get my point....

15 February 2014, 23:29	#12
Amiga_CDTV Mind Walker Join Date: Oct 2013 Location: Helsinki, Finland Posts: 165	prowler: whoah, that's so cool. Are there instructions for this mod? I got a couple of this exact model of drives (saved from a lot of recycle-going PCs), I have already coverted two to DD Amiga drives. I would love to test this HD mod on one of those drives. Also nice to know that these are drives of good quality.

15 February 2014, 23:51	#14
hese Registered User Join Date: Sep 2008 Location: Somewhere Posts: 223	It's a MicroniK Power M-Disk HD drive with custom GAL code. And the GAL chip is most likely read protected so no duplication is possible.

18 February 2014, 06:41	#20
Loedown Precious & fragile things Join Date: Feb 2009 Location: Victoria, Australia Posts: 1,946

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