FDS reads but not fully

[80sFREAK]

 This is really nice story about adjustments, BUT... remember, it was a mass production, which involved human resources.

I think "lock tight"(red or blue glue like substance) on a spindel screw confusing. It is just "lock tight" and you don't have to adjust spindel. Sorry, if someones world started falling apart 

That's right, track on the disk is spiral and spinning, so to find beginnig of it you can <censored> around spindel or adjust head unit. Maybe someone should make cardboard model of moving parts to see, that disk is just spinning, head moving following guiding disk and spacing controlled by spring loaded screw on the head unit. That's right, you can catch beginning of the track by "adjusting" spindel, or take easy route and adjust head unit. And no, don't measure alloy parts without processed sides by caliper. It's alloy.

And the last note. Since we don't have original official Nintendo calibrating disks, we will have three groups of "calibrated" drives. 1)those, who "came on track" from outside; 2)those, who "came on track" from inside and 3)most lucky, who got "to the center".

It is possible to recreate calibrating disk with quite high accuracy, but you will need as many disks as you can get(i would say 50+, maybe 100, the more the better), a drive, tools include caliper and A LOT of time to fill up this table

# disk	stop read "out", mm	stop read "in", mm	average, mm
1	xx.xx	yy.yy	zz.zz

It must be done on the same drive, by the same tools and the same person. The key is amount of disks original or rewritten back in the days. I'm sure some fake "originals" might popup during this test 

[oare]

That's right, you can catch beginning of the track by "adjusting" spindel, or take easy route and adjust head unit.

My first instinct when reading your message was to post something to the effect of:
a dead mouse might be a very important thing to the eyes of an owl, but to me, it's just a worthless rodent corpse.

However, here, you're saying things that are really potentially harmful to drives, so I feel I have to reply a little more thoroughly.
First, let's agree on something for once: yes, we're talking about a rotating disk, yes, w're talking about a head that moves along that disk, so yes, theoretically, you could calibrate your drive be either: a/ moving the spindle hub so that when the guiding pin locks into the disk, it falls at the right position relatively to the head or b/ moving the head so that it is at the right position relatively to the guiding pin on the spindle hub.
All we need is to have the head and the disk both in the right position so that when the drive begins its reading sequence, the RAM adapter gets the appropriate data fed to it. That's what I've been saying since the beginning.

But solution "b" certainly isn't "the easy route".
First, because the head only has a physically limited moving span. Once it reaches either ends of its rail, it can't go any further than that. So even if the drive had the ability to "wait" until it finds the data track on the disk to start it's reading sequence, positioning the head just a little too far in would mean that it could never reach the end of the data track.
And second, because trying to find the right position of the head by turning the head  would be a nightmare.
Open an FDS drive, and make just one rotation with the lower gear.
See how much the head moves? It's practically zilch. Tenth of a millimeter. Yet, the position of the guiding pin (and hence, the orientation of the spindle hub) has to be right within those tenth of a millimeter, or things won't work. If it can convince you, try this: reposition the spindle hub just a quarter of a turn. Chances are your drive won't read at least a few of your disks anymore. And that quarter of a turn is only a quarter of those tenth of a millimeter.
Now, take a screwdriver and make the smallest turn you can on the head screw. I'm willing to bet you won't have "tenth of a millimeter" of precision. Or you've got bionic hands and eyes. Trying to find the right head position by turning the head screw just isn't realistic.

So what's the reasonable course of action?
The answer is simple: trying to understand the process through which drives were calibrated by Mitsumi, in order to reproduce it.
This is what I'm doing here. I'm not the first. And I'm sure I'm still missing a few things and steps, it's a work in progress.
But it does work. Since I've started doing things this way, I have a 100% success rate in repairing FDS drives. In less than 30 minutes. Every. Single. Time. Do you think it is a coincidence?
One thing is for sure: there are a lot of markers on the drive. The hole in the bottom plate, the hole in the triangle bracket, the black hole on the lower gear, the holes in the head leading plate, the hole on the upper part of the drive. Just to name a few. Here's a question for you: why did somebody decide to put those there? Decoration?

[80sFREAK]

If you ever calibrated FDS, you should know, how many turns is "reading zone" 

First, because the head only has a physically limited moving span. Once it reaches either ends of its rail, it can't go any further than that. So even if the drive had the ability to "wait" until it finds the data track on the disk to start it's reading sequence, positioning the head just a little too far in would mean that it could never reach the end of the data track.
And second, because trying to find the right position of the head by turning the head  would be a nightmare.

You just shoot your foot 

[oare]

If you ever calibrated FDS, you should know, how many turns is "reading zone" 

What?
Sense. Try to make some.

Or rather... Forget it.
Keep posting in your inimitable Pythia style.
I'm actually enjoying it.

You just shoot your foot 

Nope.
Now that you mention it, I'd love to try it just for fun, but unfortunately you're using all the bullets.

[80sFREAK]

Nice, very nice story. Keep going  At least it breaks okame's monopoly 

[fredJ]

Okay, I have been trying now, but I can't follow the guide.
Maybe someone else can try and clarify the steps?

The two holes are supposed to be aligned, but I don't understand at what stage they are to be aligned. Is it when the drive is in its position to start reading?
I think I need a guide for the guide...

[oare]

Okay, I have been trying now, but I can't follow the guide.
Maybe someone else can try and clarify the steps?

The two holes are supposed to be aligned, but I don't understand at what stage they are to be aligned. Is it when the drive is in its position to start reading?
I think I need a guide for the guide...

The holes need to be aligned when you screw back the gear assembly into the drive and pull the new band down to the motor pulley.
That is, before you start hand-turning the gears in order to find the right position for the spindle hub (the "click").

I should add a picture to clarify this.
I'll try to do that later today.

[fredJ]

okay, I understand now, I think.
The one hole is so positioned that you can see it through the plate. And the other hole is aligned in a straight line from it.

But on most model FDS systems, there are two holes in the plate, not in a straight line. I am thinking that maybe one plate hole is to see each hole in the mechanics? Since you mention the importance of the plate holes so much.  

I appreciate the guide, but I am not sure if this calibration is more accurate than the "trial and error" head repositioning... I had a hard time getting the two holes in a perfectly straight line, and they easily get out of align when you put in the gears so I am not sure if they are 100% perfect anyways. A little head adjustment fixed the problem.

But I think on earlier model FDS:s this would be a useful technique I will try out.