FDS reads but not fully

[zmaster18]

Lately I've been fixing up another batch of disk systems and found some weird problems, one of them I solved by myself.

The problem I fixed myself was I had a drive that read games perfectly but for some reason would not save whenever I tried to save in game. It would give me error 03. The problem here was that the cable that plugs into the drive unit was seated crooked and perhaps the lead for WRITE wasn't connected. I reseated the cable after I noticed it and worked great after that.

Now, I have one disk system that does read disks except it has trouble reading side B's of games and gives me error 27 and doesn't save when I try and save in game and then gives me error 40 for that. I have been doing many spindle adjustments and motor speed adjustments and yet side B of Zelda won't load even though it loads in another disk system.

I've put this drive aside and am working on some other ones for now. Should I just keep making adjustment after adjustment? I've been working for hours on the same drive... I'm really getting frustrated with all the trial and error involved in the process 

[fredJ]

Yes it is very frustrating. I recently had a drive that would just give me errors, and it was like feeling "I'm almost there"... but after 1-2 hours I gave up and took another.

I don't think that it has to do with calibration. Maybe a defective chip like some people here seem to have, or a line that is wrong on the circuit board, corrision somewhere, etc. I once had a very difficult FDS and I replaced the circuit board on it (simple even for me) and it worked perfectly.

[80sFREAK]

games

Zelda

Anything else on the list?

[oare]

I don't think that it has to do with calibration.

There's actually one step in the calibration process that I've seen covered nowhere in the english guides available here an there. Without this step, some drives, especially early ones, tend to keep giving errors even when the spindle is seated properly.
Basically, when putting back the gears together, the upper gear (the one with the metal plate) has to be properly aligned with the lower gear (the one with the black hole in it), and the whole assembly has to be put back into the drive in a certain position (aligned with the hole in the traingle bracket some drives have).

When I have a little spare time on my hands, I'll do a comprehensive guide and post it here.
I've repaired quite a bunch of drives, and even the most stubborn ones work perfectly when this step is properly done.

[zmaster18]

Ah thanks, I was thinking it had to do with the positioning of the gears for the other ones I'm fixing. For the one that reads but throws errors, I'm going to try resoldering one part of the board that looks a little dull.

[80sFREAK]

Ah thanks, I was thinking it had to do with the positioning of the gears for the other ones I'm fixing.

Do not forget, it must be done at proper phase of the moon  Also add some lubricants 

Look, seriously, think about how whole thing working. There is no "index" hole, so disk just spinning. Excentric disk move head unit here and there and there is a switch, which remind BIOS to start reading. That's all.

[fredJ]

I don't think that it has to do with calibration.

There's actually one step in the calibration process that I've seen covered nowhere in the english guides available here an there. Without this step, some drives, especially early ones, tend to keep giving errors even when the spindle is seated properly.
Basically, when putting back the gears together, the upper gear (the one with the metal plate) has to be properly aligned with the lower gear (the one with the black hole in it), and the whole assembly has to be put back into the drive in a certain position (aligned with the hole in the traingle bracket some drives have).

When I have a little spare time on my hands, I'll do a comprehensive guide and post it here.
I've repaired quite a bunch of drives, and even the most stubborn ones work perfectly when this step is properly done.

I can't see how there can be more than one way of placing the gears....
The gear with the metal plate is just a gear, identical on all sides. It doesn't have a start, finish or specifics to it.

[oare]

Whoa, that's some pretty harsh comments here.
I just wanted to help.
The metal plate is not identical on all sides, it serves as a guide for the head position.
If the alignment is properly done, it is easy to make all drives work in one shot, even the earlier models. That's all.
There are actually plenty of physical markers on the drive assembly to indicate how things are supposed to be put together.
But if you guys aren't interested, I won't make that guide.
It's not like I'm going to make money out of it or anything anyways.

[zmaster18]

Whoa, that's some pretty harsh comments here.
I just wanted to help.
The metal plate is not identical on all sides, it serves as a guide for the head position.
If the alignment is properly done, it is easy to make all drives work in one shot, even the earlier models. That's all.
There are actually plenty of physical markers on the drive assembly to indicate how things are supposed to be put together.
But if you guys aren't interested, I won't make that guide.
It's not like I'm going to make money out of it or anything anyways.

Hey man, there's no one being offensive in here. We're all interested in what you have to say about the gears. I totally believe everything you said and will be trying to align the gears tonight and taking your advice into consideration.

[80sFREAK]

I can't see how there can be more than one way of placing the gears....
The gear with the metal plate is just a gear, identical on all sides. It doesn't have a start, finish or specifics to it.

SUDDENLY agreed 100% 

The metal plate is not identical on all sides, it serves as a guide for the head position.

so what? There is a switch, if you noticed, which let BIOS know, when to start reading(if this switch is not working, you will see LOADING... forever, but that is another story).

Take calibrated drive, unscrew circuit board from it, screw it back... most ikely your drive will stop reading disks. Why? You shifted little bit switch, so head lost the track.

[oare]

I can't see how there can be more than one way of placing the gears....
The gear with the metal plate is just a gear, identical on all sides. It doesn't have a start, finish or specifics to it.

SUDDENLY agreed 100% 

In a nutshell:

The lower gear, which controls the spindle hub movement, moves together with the upper gear, which controls the head position.
So after a given number of rotations, the relative positions of the spindle hub and the head will always be the same.
On the spindle hub, there is a little piece of metal that latches into a hole on the disks.
So the position of the magnetic disk is also always relative to the position of the head.

The FDS accesses data in a sequential manner, so it requires the head to point to a very specific area of the magnetic disk at the beginning of its read sequence.
If the spindle hub is not initially properly positioned relatively to the head, the head will point to a wrong place on the disk. Which will result in errors.

This explains why, when the initial alignment procedure hasn't been done correctly, people have to tediously tinker with the spindle hub position.
What they are actually doing is blindly trying to orientate it so that it is properly positioned relatively to the head.

[fredJ]

okay, you are referring to these two wheels?



I thought you were referring to the gear that is not in the picture.

I don't remove the two wheels in picture, so I suppose you could be right about their calibration. But this would indicate that trial and error of the spindle hub would fix the problem even if it takes time, no?

[oare]

But this would indicate that trial and error of the spindle hub would fix the problem even if it takes time, no?

It should, but the margin of error is quite narrow so it's easier to just sit the gears properly from the start.
Another thing that might need tinkering with is the motor speed. It is easy to do since it only requires a small flat screwdriver, and is readily accessible.

I've just bought another FDS on auctions, so I'll make the repairing guide during the week-end.

[zmaster18]

Wow thanks a lot, that is very much appreciated! I'm looking forward to it!

[ebinsugewa]

I've just bought another FDS on auctions, so I'll make the repairing guide during the week-end.

I repaired my FDS seemingly by chance and would like to learn more about doing it properly, have you considered making this again?