Advice needed to diagnose Apple ii disk drive problem

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Joined: Jan 12 2011
Posts: 32

I have (or) had a working Apple ii Europlus which I have been using as a benchmark machine to restore a second ii Europlus (my project machine). I arrived at the point where the project machine is fully working and has a Super Serial card on board and has successfully linked to ADTpro. So it was time to get one of the spare Disk ii’s I have working with it. I found that neither of the three drives I have performed as expected and after a little head scratching, noticed that the controller card has a number of chips with ‘black corroded’ legs.
So, I reluctantly took the step of hooking one of the drives to my working benchmark machine through its functioning controller card. The drives ran up some speed upon switch on, but kept running and did not stop. It continued to run when I hit control /reset so I knew I had a problem. I tried a couple of disks in it and the problem was the same. I changed, drives and it exhibited the same problem, so I switched back to my one working drive through the working controller, which then exhibited the same problem…damn.
I re-seated the controller card, checked the drive connector to the card but the one working drive I have is not working in the benchmark machine. Tried my trusty dos disks, same symptoms, whatever I do.

I have a new controller card on order from the USA anyway, but that will take time to travel to the UK, but are there any other things I can
try with my formerly working drive and controller card to test / get it working again.

As always, thanks for your advice.

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amauget's picture
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Joined: Jan 3 2011
Posts: 242
Re: Advice needed to diagnose Apple ii disk drive problem

Hello Atomtan,

No luck this time Sad

Except from the P5 and P6 Roms, the IC on the Disk II controller are common (74LS and 556).
You can try to change them.

If you have access to an oscilloscope, you can check the signals using the SAMS Disk II book.
You will also find interesting informations in the "bible" Understanding the Apple II which is available at the same location that the SAMS book is.

edit : OK, I've just seen your other thread...

Regards,

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Antony
Apple II forever

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Joined: Jan 12 2011
Posts: 32
Re: Advice needed to diagnose Apple ii disk drive problem

I fixed one drive with a 74LS125, and diagnosed two bad controllers cards, which leads me to:

Can anyone offer further guidance in trying to fix 2 x Disk II drives. Both power up, but neither of them ‘run up to speed’ and one appears to ‘vibrate’/’shake’ as the disk spins (albeit not quickly enough to begin reading). I have swapped controller cards and even Apple II's and they both show the same symptoms. I have swapped the 74LS125 chip, and re-seated all other chips on both and nothing improves. The drive belt is connected.

I don’t want to junk them, and one is a pretty early drive, and wondered if I should combine components from both to make one good one. I can work with trial and error, but as both get power, and attempt to spin up (though one vibrates) I thought about swapping boards over first. The large connector on the horizontal board appears to be secured with some sort of plastic clips which I assume I can break to disconnect.

I have a new MC3470, is it worth swapping this first?

I dont have access to and ocilloscope, so am not starting with the best tools.

amauget's picture
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Joined: Jan 3 2011
Posts: 242
Re: Advice needed to diagnose Apple ii disk drive problem

Hello Atomtan,

You can disconnect the large connector simply by pulling it. The plastic clips will be moving out of the holes. I have never break one of them.

Do you have almost one known good controller and disk drive ?
If so, I suggest you connect one of the defective drives in Drive 2 port. So you can run some diagnostic software like MECC Computer Inspector and try to see what's going on.
But without an oscilloscope, it will be hard to find the culprit(s).

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Antony
Apple II forever

speedyG's picture
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Joined: Nov 16 2011
Posts: 2376
Re: Advice needed to diagnose Apple ii disk drive problem

hello,
without an oscilloscope it might be the best choice before playing with the 3470 to make a trusted working DISK II to the first drive on a trustable controller ( besides MCpricebreaker at ebay have DISK II Controllers on stock and they are reliable fast working dealers ) and one of the not vibrazting drives to be drive II on the controller and startup with the drive speed software on different kinds of software ( Locksmith , dealers diagostic etc.) and to start the examination of the drive 2 by calibrating the correct speed with the spindletrimmer at the backpanel board in the drive II. In most of the cases the malfunction is caused by that. The second problem to possibly fight is the realignment of the track 0 indicator ( a a fork light barrier in the mechanic related to the alignment of the read/write head on the slide-mechanic ). before it might be a good idea to clean the head with alcohol and a Q-Tip ; and don´t forget when calibrating - to view from the side to the head on startup... the "vibrating" drive might have a problem with the positioningwheel on the lower side of the disk because the very small ball on the spring jumps out of the scratchrail in that wheel - that might prevent the head from correct positioning....
usually at startup the drive allways tries to recalibrate to track 0 on spinup... and if it doesn´t get track 0 it won´t stop trying to recalibrate.... the missing points may be the track 0 indicator ( the forked light barrier which might be repositioned by untightening the screw , fixing very carefully and very gentle the position and then tightening the screw again ). Then continue with the speedtest.... start with large tolerance spread and proceed with smaller tolerance test... otherwise you take risk by starting with small tolerance test that you never get the measurepoint moving from one borderside of the testdisplay away....

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