I got hold of a damaged disk drive for my ][e, it appears to have suffered a fall from a great height as the case was dented, the disk rotating flywheel and bearing had dropped out and the pcb mount had snapped off of it's mounts to the casting.
These are all rectifiable but the head drive stepper motor appears to be seized solid - which seems very odd for a stepper motor.
The spiral disk that drives the head is a press fit onto the shaft of the motor.
Anyone taken this apart?
Anyone know where I could find another stepper?
(I know these disks are pretty cheap on ebay, but in the UK they are hard to find and US shipping is megabucks!)
Hello richard-iii,
well mentioned several times in the past....
view the pages at :
http://www.appleii-box.de/H084_1_AppleIIDiskService1.htm
including the following pages and read the stuff...
when finished, i believe you will be prepared to attempt the repair...
sincerely speedyG
Thanks speedyG,
I found some of that site while googling last night.
Unfortunately it doesn't go as far as taking the stepper out, but certainly explains how to get the drive back together and aligned.
I'm going to extract the stepper now and see if it will free up or if it's fried!
Hello Richard-iii
i would recommend - before extraction -
to first examine function of the steppermotor and the electronics driving the motor....
If the case is open and the analog board is untightened cables are long enough to move
that analog board to the side where the read/write cable is aligned to the frame...
that cable can also be untighted - if you keep in mind, that it must be that kind loose
that the read/write head can move free without damanding to drag that cable...
that would at least offer a view to the alignment disk and you could examine
while booting and performing read/write tests, if the positioning ball
is really keeping within the positioning notch of the positiongwheel and if the
steppermotor gets the signals for positioning from the rear electronic board,
then it might rather more be a question of track alignment, instead of replacement.
And in case of replacement - it might turnout to be more needed to replace the
rear electronic PCB - instead of the motor because the motor does not get correct
signals for stepping...
I doubt the motor to be dead... that devices have been built like tanks....
they would usually survive a drop from 10 feet or more....
in such case of drop - the printed circuit board at the rear - is rather more suspicious for failing
i.e. damages of the PCB - close to the fixing points where the screws hold them tight to the frame...
speedyG
Hi SpeedyG,
The impact was such that both guide rails/rods moved so far that they where bending the rear pcb!
I have just pressed the motor out from the spiral head disk.
The motor was jammed and once I freed it, it turned freely 180 degrees and then jammed again.
I took the sticky cover off the back and could see that the rotor was binding with the windings!
So the impact knocked the shaft out of alignment.
I just put the motor in a vice to see if i could re-align the shaft bearing and it appears that the outer case was dislodged because when I tightened up the vice (gently) the case moved together slightly and the shaft centred up.
It's now turning freely, so I will re-assemble following the guide you showed me and see if it runs.
I think the disk rotation motor will probably be knackered too, but you never know...
I'll post what happens.
that sounds like an outraged wife throwing the drive towards the husband - missing him -
and the drive then dropping from 9th floor to the basement....
you really need VERY HEAVY IMPACT to cause such damage...
what happened with the rest of the computer ?
Did that anoyed wife give them a "special treatment" with the frying pan ???
did the husband survive the attack ???
LOL
speedyG
Ha ha ha! (I mean LOL!) LOL!
The funny thing is that I got this drive off ebay and it was described as having a damaged cable and some scratches on the case.
When I got it, all I could hear was rattling as numerous bits fell about inside.
The case looks like it was dropped onto concrete from at least a 2nd story or maybe it literally fell off the back of a lorry. (a euphemism in the UK for being stolen)
I'll post a pic at some point....
After being rather dismayed, I complained to the seller and he did the gracious thing at refunded me. As I had told him the packing was fine and I'd binned it, he just said 'forget it' and let me keep the drive.
Opening it up I found a bearing, a small metal tube, the write protect finger (plastic bit), a flat metal plate, a belt and a flywheel, all loose inside.
The whole control pcb was still attached to the plastic mount but the mount had completely detached from the chassis.
I got it all back together and found the jammed stepper....
Anyway, believe it or not, after a quick squish with a vice, I just assembled it all and it booted a disk!!!
I skipped the track zero alignment and just put the motor back where the loctite marks were!
I powered it up and it did the Apple Rattle - no smoke! Put in a boot disk and hey presto!
It's reading a disk that I formatted on a completely different drive. What are the odds of that!
You can tell I am well chuffed! (as we say over here)
I just need to repair or replace the dodgy cable that has been torn so six of the wires need joining.
Looking at the drive maintenance info I found, people seem to lube the drive head guides but the apple manual says that's a no-no.
I also ready two methods for setting the head carriage track zero position. One with an 0.08" feeler gauge between the stepper shaft and the stop and another with a 0.02" gauge and adjusting the screw holding the carriage limiter.
The most important thing while adjusting track 0, is to pay attention to the drilled marks in the positioning disk and adjusting the spacing while the ball in the slidingnotch is just exactly opposite to the marks on the positioning disk.
Just exactly following up the description in my pages will leed fastest to success...
so good luck with the resurection of the drive...
speedyG
Well it all seems fine! I now have both drives running.
Good work... And Speedy, great document detailing calibration as well as other important Disk II info. A keeper in my A][ archives for sure.
If he didn't, then he would not have sold the drive.
and if he would have been killed - the surviving wife might have sold it...