How important is FDS spindle alignment, really? I say not at all.

[Phil_Bond]

I have an FDS and five disks. When I first started playing with it, they all worked. I put it away for two years, got it out again, and found that Zelda II was usually loading with a graphical glitch in the overworld, and Doki Doki Panic side B would no-longer load at all.

So I did a lot of reading, looking at pictures and watching repair videos on YouTube, and decided I was going to open up the drive and check all the things that might be out of optimal calibration. I tore it down to the point where I could remove the hub on the top of the disk spindle, put the allen wrench in, gave it a tiny turn, and slipped the hub off carefully. On the spindle, I saw two pinpoint indentations at the latitude where the hub's grub screw is supposed to poke in. There was a tiny, faint indentation at the radian where the grub screw had been nestled, but there was also a much deeper indentation  about 160º clockwise from that spot. This second, unused indentation looked more deliberately machined, whereas the used indentation looked like it had been made with nothing but the pressure of the point of the hub's grub screw. This deeper indentation appeared to me as though it represented the manufacturer's intended position for the hub, so I reassembled the drive in the hopes that this was the calibration error that had been giving me trouble.

It wasn't. The drive ran exactly the same, with the exact same errors as before. Moving the spindle hub to a radically different position had no effect whatsoever on operation. The problem turned out to have been in the position of the read/write head.

So what gives? When I was reading all those guides and watching all those videos, plenty of people stressed the importance of positioning that hub, but it seems to me that it must not be important at all. Not even a little bit.

[Da Bear]

I would say otherwice. It IS important.

The reason why your spindle isn't in factoryposition is probably due to a prior belt replacement.

I just made a thread on how to correctly align the spindle hub.

http://www.famicomworld.com/forum/index.php?topic=6723.0

[fredJ]

I think the importance of having it in the absolute correct angle is exagerrated.

But if it is completely off, in the opposite direction for example, you will find most games won't work. I don't know why it worked for you.

[ericj]

After having read, dumped, and written hundreds of games on multiple drives, I have to disagree with you.

Both the alignment and proper height of the spindle hub are the most important things, since the hub determines the start point of the disk data in relation to the drive head. One of the reasons pirate disks are notoriously troublesome to read is because they are usually written using a maladjusted drive. To properly read them, you have to adjust your drive to match the one that wrote the disk. Adjusting the drive like this works nearly all the time (only time it doesn't is when the disk is physically damaged), so I can tell you from experience that the hub's position is vital to being able to properly read a disk.

Adjusting the magnetic head position is just asking for trouble. In my estimation, you had the height of the hub incorrect and compensated by moving the read head's height. I think you got lucky.

[Xious]

I've been saying that forever: Adjusting the head position is essentially like asking the drive mech to become faulty. The only times I have needed to do this are when the owner has meddled with it before sending the drive to me.