Amiga 500 Internal Floppy Disk Problem - Fixable?

[gzsfrk]

Hey guys! Hoping an old-school Amiga head might can help me out here. Recently picked up an Amiga 500. Powers up just fine, gets to the Kickstart 1.2 insert disk screen. But when I would insert a disk, the disk activity light would turn green and I could hear the head clicking, but nothing would load.

 

I got to listening more closely and realized that the disk wasn't spinning. So I disassemble the A500 and clean everything. Take out the floppy, disassemble and clean it. Pretty dirty, but not catastrophically so.

 

I put the floppy drive back together, hook the A500 pieces up (while still disassembled), fire it up, and still encounter the same problem: system recognizes when I insert the disk, disk activity light turns green, but the disk doesn't spin. So I turn the floppy drive on it's side so I can see the drum underneath an began to experiment. I found the when the disk activity light turned green, if I manually nudged the drum in the right direction it would spin up and read the floppy, letting me get into Workbench 1.2. But the timing had to be just right, or it just results in a disk error. I've gotten pretty good at it, though, and have been able to successfully load and run several programs. But I can only do it as long as the A500 is disassembled with the floppy drive bottom accessible.

 

So the obvious two questions: Does anyone know whatnots doing this? And how might I fix it? I don't think it's the motor seizing up; the drum spins quit freely by hand. It's almost like it's some kid of sensor issue, or possibly a weak capacitor? Really not sure. Hence why I've come to the experts.

 

Thanks in advance for any help! Let me know of you need any details or picture for the A500 or drive.

[Osgeld]

I dont but my best guess is that the drive spin motor has enough crap in it to cause a stall, or there is not enough current to overcome a stall condition

 

electric motors in a stall condition consume TONS of current, which can and will burn out the motor controller or on up the chain to the power supply

[Seob]

Could be a broken disk detection switch.

[Keatah]

IIRC the Amiga drives turn on the motor only when a disk inserted. There were times my 500 wouldn't spin up unless I jammed the disk or wiggled it just so.

 

I am not versed in the specifics of the Amiga drives so aside from saying look for a switch or optical sensor I couldn't walk you through a troubleshooting session.

Edited September 28, 2014 by Keatah

[RodLightning]

I dont but my best guess is that the drive spin motor has enough crap in it to cause a stall, or there is not enough current to overcome a stall condition

 

electric motors in a stall condition consume TONS of current, which can and will burn out the motor controller or on up the chain to the power supply

Could it be a bad capacitor somewhere in the drive's motor control circuit? I would explore that before replacing the drive. Edited September 28, 2014 by RodLightning

[Osgeld]

it could yes

[gzsfrk]

I don't think it's the disk sensor switch, as the drive activity light turns green and I can hear the head moving when I insert a disk.

 

I'm intrigued by the bad capacitor possibility, though. Does anyone know of a site or repository online that has Amiga floppy drive schematics?

[+save2600]

Aminet.net/docs/hard might have something.