I recently pulled out a Disk ][ that had been kept in a drawer for several years. It was working when I put it away, but now it's not.
It powers up and makes the normal head banging sounds if I try to boot from it but then just spins the disk forever.
If I boot from another drive and try to read from it or format a disk with it, I get IO errors.
I opened it up and cleaned the head (which wasn't terribly dirty), but that didn't make any difference.
What else could've gone wrong with it? It's possible it got bumped around a little bit in the drawer but mostly it's just been sitting.
Was the drawer indoors or outdoors? If it was outdoors, thermal cycling can cause problems. You can possibly get cracked solder joints or chips loose in their sockets. If there was condensation there can be oxidation or rust on components.
Electrolytic or tantalum capacitors can age as well. Sometimes you can tell if there is a problem by testing the power supply rail. A bad capacitor can cause a lot of current draw and the voltage to sag.
It could also be a mechanical problem, for example, lubrication of the stepper motor or rails may be required. Also the drive belt may be loose or worn and need replacement or tightening.
There are 4 logic chips of the analog board. That’s the board you see when you remove the case. They’re all socketed so very easily replaced. One controls the read cycle one controls the write cycle. Etc. I forget which is which but I’ve had the write cycle one fail in me where the drive stopped formatting disks. One of the 4 ICs is labeled 74LS125. Notorious for blowing. If the ribbon cable is accidnently put on the controller card a row off it will blow causing the drive to just spin. I’ve had several of these blow on me due to my poor eyesight installing the cable. Cleaning the head was a good start. Did you clean the rails the head rides on as well? Make sure the head is moving freely on the rails. Sitting for long periods of time they can stick on the rails preventing the head from moving properly. I’m far from an expert on these drives but I’ve had pretty good success in repairing several drives with issues like yours. The logic chips I mentioned are all readily available from distributors such as Jameco and fairly inexpensive . I would start with the LS125 as I mentioned. A drive just spinning endlessly is one of its symptoms. Also check the cable for continuity and signs of visible damage. I’ve had cables that looked fine but told me every disk was write protected. Cable was bad. Those are items I would personally check first based on my personal experience with these drives and what commonly goes wrong with them. Granted it could be something deeper but I’d start there.
My Disk ][ has to be at least this far from my Sony Trinitron in order to work. If I move it any closer it will not boot and I also get I/O errors if I try to read from it. I am not saying this is what's wrong with yours, I'm just putting it out there as a possibility, since I had the same situation where it was working perfectly before (without that TV of course), it just sat in a drawer and then it was broken.
Before swapping components or heating up your soldering iron: did you check the drive's speed? There is a trimmer on the motor controller board and a 50/60 Hz strobe disk on the bottom of the drive, which works fine with any incadescent light source (anything that slightly flickers with the frequency of your mains power). It's a pretty simple test/calibration step. It's described in many forum posts.
That would be the first thing I check, since it's the least invasive.
You should try adding some shielding to the monitor case. Ideally, some aluminum foil along the right side of the monitor connected to ground. If you're willing to remove the case, you could do this on he inside.
That would definitely help. I also have aluminum tape for chimneys, which would be even better. Monitors are shielded like crazy, but TVs like this one have absolutely no shielding inside - just a plastic cover and that's it.
Thanks for all the ideas and suggestions!
I think it turned out to be an issue with the drive speed. I did the incandescent light bulb thing and it was pretty noticeably off. Once I got that adjusted and did a little more cleaning inside, it gradually started to work.
At first it showed a lot of errors when I tried verifying disks with Copy II+, but as I continued to exercise the drive they reduced in frequency and went away. Maybe the sled was kind of stuck and needed to be loosened up? Anyway, it now seems to be working fine.
Those rainbow cables are completely unsheilded, which was a big problem like this early on.
They replaced them with the thick sheilded grey cables to fix this.
Be sure and reseat all the cables. Clean them with Deoxit or similar. Just to be thorough.
One thing that deteriorates on these drives over time is the belt. It's some kind of rubber/fiber composite and it will dry rot or something over the years and harden or even fall apart.
I think there may be replacements for these, but not sure where to get them.
Console5 sells drive belts. They specifically list the Apple Shugart drive belts. But don't list the Alps ones. At least not as Apple. They do sell Alps belts for the Commodore 1541.
Which having looked at both an Apple Alps and a 1541 Alps chassis, I see no reason they aren't the same belt. I've never had a reason to try them on an Apple Alps. But would have no reservations trying them if I needed one.
Thanks for the info! That's good to document out there!
I am 99.9% certain that the belt that fits on the 1541 drive will also work on the Apple II Alps based mechanism. Mind you, there were two flavours - the metal case Disk II Alps and the Aple 5.25"" Alps. I believe that the belts are interchangable between them but I will have to verify.
I'm thinking I should order a few spares for both Shugart and Alps just to be on the safe side in case these become unavailable....