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Old 21 July 2019, 09:45   #1
hadoque
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Amiga 500 floppy drive spins up and nothing more

I bought an Amiga 500 with the floppy drive not working. I cleaned out the drive with compressed air and isopropyl alcohol on the magnetic heads.
When I insert a disk the drive spins up and then nothing happens. It was a long time since I used an Amiga, so I don't quite remember the correct drive sounds, but this sounds wrong. As seen in the video, I brought the magnetic head out, so that its obvious that the drive can bring it back in before trying to read.
To me, this seems to be a problem with feedback on the spin of the disk. The drive doesn't seem to control the spin, it just goes max. Can it be a problem with the magnetic sensor on the rotor?
The drive is marked "EPSON SMD-400".
Any leads to what the problem might be is appreciated.

[ Show youtube player ]

Hope the youtube link works, I haven't uploaded a video to youtube in ages.
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Old 21 July 2019, 10:28   #2
solarmon
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I assume you don't have another working floppy drive to test in this Amiga 500, or to test this faulty drive in another Amiga 500?

Has the Amiga 500 been checked/cleaned for damage and/or corrosion?

Check the floppy disk data cable and connectors and pins (at both ends) to check for any damage/corrosion; and that it is connected the right way - pin 1 to pin 1, etc.

Check the floppy disk power cable with a multimeter - the floppy drive will need +5V and +12v going to it.
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Old 21 July 2019, 10:30   #3
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Or, the EPSON SMD-400 floppy drive might need a recap.
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Old 21 July 2019, 10:38   #4
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Some other things to check:

* It has been configured for DS0 - check the jumper settings on the floppy drive.

* You should also check the sensors/switches on the floppy drive - if the 'disk presence' sensor is working then that could be the issue.
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Old 21 July 2019, 11:29   #5
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Thanks for those hints. I agree, best would be to test in another amiga, I’ll see if can get a hold of one.
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Old 21 July 2019, 14:41   #6
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I've looked a bit more at the drive now, and I discovered some corrosion close to the input side. Maybe something has leaked into the drive? Anyways, I would like to dismantle the PCB's so that I can clean and inspect them (and recap), but I can't figure out how to take this thing apart. I can't find any screws that seems to hold to mechanics together. Anyone know how to go about?

Image of corrosion attached

Edit:

I managed to wiggle out the two mechanical pieces that sit above the affected board, but now I'm having problems with the motor. There are screws for the bottom PCB under the motor. How do I loosen the rotor of the motor?
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Last edited by hadoque; 21 July 2019 at 15:04.
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Old 21 July 2019, 15:06   #7
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Image of motor rotor.
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Old 21 July 2019, 16:12   #8
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Take a picture of the underside of the board. Normally, there is a metal or plastic washer that can be removed that releases the spindle.
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Old 21 July 2019, 16:23   #9
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I would also check the sensors switches on the left. Not sure whether that is corrosion or just dirt/fluff on the legs, but it should be cleaned with isopropyl alcohol.

One should be disk present sensor and the other a write protect sensor. Use a multimeter in continuity mode on the legs and see what happens when you press down on the switches.
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Old 21 July 2019, 18:52   #10
hadoque
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Hooooo

Bottom side of drive.
I noticed that the board with the corrosion is a metal substrate pcb, so I don’t think I need to care about anything on bottom side, so I might not remove it...
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Old 21 July 2019, 22:58   #11
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Since it detects a disk when inserted (hadoque mentioned that disk starts to spin) the disk presence sensor is obviously working.

I have exact the same floppy drive in my original (bought back in the 80s) A500 and it shows the same symptoms. I haven't managed to fix this but I'm convinced that the solution is probably a recap. It seems some of the caps have failed and the motor does not spins at the correct speed any more. However dismantling this drive does not seem like an easy job at all and myself also haven't figured out how to do this without causing damage...

hadoque if you manage to do it (without breaking the drive of course :P) please post a how-to along with some photos!
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Old 21 July 2019, 23:36   #12
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Yeah , disk detection defenately works.
Sure, I can make a guide on how to dismantle as far as I got , I don’t seem to have broken anything yet. Where would be the best place to publish it?
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Old 22 July 2019, 01:04   #13
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Perhaps since the 5 caps visible are SMD you could try replacing them without further dismantling the drive? At least C08, C09 and C10 seems accessible.

For posting a guide - and your findings in general - I suppose this thread on EAB is fine!
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Old 22 July 2019, 02:12   #14
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did you try swapping the CIA chips?
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Old 22 July 2019, 10:38   #15
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Here is an article (in German) of a EPSON SMD-400 recapping:

https://www.jungsi.de/epson-smd-400-...bung-atari-st/

Although, this recapping replaced the 10uF SMT caps with through hole ones.
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Old 22 July 2019, 23:03   #16
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I will test a recap. I am waiting for delivery of new caps. If I'm successful, I will document it on my blog and link to that from here.

Here we go:
Mounting bracket and casing of drive has been removed (easy). If you need to use force, you are doing it wrong.

Step 1.
Remove lock-screw and spring, marked in the first image.
Push the disk ejection button to release the upper disk holder mechanism. Push it forwards-downwards to release it.

Step 2.
Remove springs marked in second image.
Push disk eject mechanism forward to release it.

Step 3.
This is as far as I've gotten. To remove motor control PCB, I probably need to remove rotor. I can't figure out how to do this.
To recap through hole cap in the magnetic head control PCB, it needs to be dismantled. I'll figure out how to do this when I get the new caps.
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Old 23 July 2019, 11:19   #17
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It looks like, to me, that the motor spindle is secured by that yellow/brass bit on the shaft itself? Have you tried to see whether this can be removed - it could either be glued on or just friction fitted?
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Old 23 July 2019, 11:22   #18
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It might not be possible to get the drive aligned again after removing the spindle.. Be sure to mark its orientation carefully before removing it.
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Old 23 July 2019, 11:50   #19
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Yeah, looks like it might be friction fitted. I’ll try banging it out if recapping doesn’t fix it...
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Old 23 July 2019, 12:03   #20
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Quote:
Originally Posted by Jope View Post
It might not be possible to get the drive aligned again after removing the spindle.. Be sure to mark its orientation carefully before removing it.
For my understanding (since I have a some Roctec drives I'm trying to fix too). How does the drive motor alignment work? I.e. what/how gets aligned? I thought that as long as the motor spins at the right speed and the rotary speed detection (using hall effect sensors?) is working then there is no other 'alignment' of the drive motor?
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