DUODISK Calibration and Adjustment

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DUODISK Calibration and Adjustment

Hi everyone,

I have a Apple IIe. I'd like to know if it is possibile find a specific diagnostic software for the step motor calibration and adjustment of the heads alignment of DUODISK drive ..

 

Thank you

 

GianDO

 

 

 

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As far as I'm aware, a duo

As far as I'm aware, a duo drive is basically just two Disk II units in one case with a different interface to support the daisy chaining of the drives. So any software that can check calibration on a regular disk II can check a duo drive.

 

The problem is locating that software, as it has to be an original mastered disk to accurately calibrate. There are some basic checks like drive speed, read write, etc. that can be done with copies of diagnostic disks. But in depth tests require using a specially created disk that is confirmed to be 100% accurate. Which can only be done on a device that is known to be 100% accurate. And may even be mastered in a way a regular disk II can't.

 

 

Apple had such a disk for service centers, as I believe so did Verbatim and probably a few others. These disks were all labeled that they should not be copied, and the program instructions warn you not to use copies of said disks. 

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nick3092 wrote:As far as I'm
nick3092 wrote:

As far as I'm aware, a duo drive is basically just two Disk II units in one case with a different interface to support the daisy chaining of the drives. So any software that can check calibration on a regular disk II can check a duo drive.

 

The problem is locating that software, as it has to be an original mastered disk to accurately calibrate. There are some basic c

 

Thank you for reply.

The specific disc is mainly used for head alignment. Meanwhile, with the MECC-A240 Computer Inspector 1.0 software I tried to correct the rotation speed using the trimmer placed under the disk units. But when I started the program I immediately noticed that the rotation speed underwent several changes, for example. 100 to 600 rpm or 55 to 400 rpm, when in reality it should be 300 rpm with a tolerance of + -0.1 / 0.2. I tried to adjust the rotation speed using the trimmer, but it seems to have no effect. If I try to bring my ear closer to the motor while it is running, I realize (acting on the trimmer) that the speed increases or decreases. Unable to calibrate. Where can the problem be?

 

 

 

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I'm no drive expert. But my

I'm no drive expert. But my first guess would be a slipping/loose/worn belt. If the duo disk uses an Alps drive chassis, then This belt may work. It's listed for Commodore, but I'm fairly certain the Alps mechanical drive chassis is pretty much identical between Apple and Commodore. But I can't guarantee that, so if you get one and it doesn't fit, don't blame me. The same site also has belts for the Shugart chassis in case it uses that. But I'm pretty sure Apple switched to Alps by the time the duo came out. Look at the drive to see which brand it is first before ordering anything. 

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Also, if you haven't, clean

Also, if you haven't, clean the drive head very well with a qtip and ipa (alcohol, not the beer). The higher the percentage the better, but regular 73% or whatever will work. Higher % has less water and flashes off faster. You may even want to do a couple wash and dry cycles on it.

 

 

The reason I say that is I'm pretty sure these drive speed programs work by writing a piece of data and then timing when they see it again, and run a formula to roughly estimate speed. If the head isn't reliably reading, it could give false data. 

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@nick3092 Yes, I was aware

@nick3092

 

Yes, I was aware that the Duodisk drives were the same as the Commodore 1541 with ALPS mechanics. The belt appears to be ok.It is true that the disk rotation calibration software requires a blank disk will probably try to write access to the disk, in fact if any data is present it will be deleted.When calibrating a completely out of order drive, do you need to calibrate the rotation speed first and then the head?As you said, if the head does not work well the rotation speed may not be reliable, but how do you then align the head if you do not calibrate the rotation speed first?

 

 

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Speed/rpm tests do not

Speed/rpm tests do not require a special disk. They usually just require a scratch (ie. Disk that can be overwritten). Which is why I believe all they do is write some data, then see how long it takes for that data to rotate back to the head. Special disks are only required for checking very specific things, like radial alignment and hysteresis.

 

If you believe the head is faulty and still want to verify the speed, you can use the test pattern in the bottom of the drive hub to verify speed. You'll need to read up on it, but I believe the idea was you would watch the hub in a dark room with a fluorescent light. There are two patterns on the hub, one for 60hz Mains like in the US and one for 50hz mains elsewhere. I believe the idea is when adjusted and spinning properly, you would see a steady pattern as the hub rotated. If the pattern moves or shifts around, you have a speed issue. Again, I've never tried that. So read up on it if you want to, as I might not be explaining it properly. 

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Locksmith

The copy program Locksmith (for example v.5) has a menu option "disk speed" which can be used to calibrate the disk speed.

It just requires a blank disk to write on.

The standard speed is 300 rpm, but you would need to lower the drive speed in order to copy certain copy protected disks.

It can't be used to calibrate the head alignment afaik.

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tolderlund wrote:The copy
tolderlund wrote:

The copy program Locksmith (for example v.5) has a menu option "disk speed" which can be used to calibrate the disk speed.

It just requires a blank disk to write on.

The standard speed is 300 rpm, but you would need to lower the drive speed in order to copy certain copy protected disks.

It can't be used to calibrate the head alignment afaik.

 

Locksmith v5 does not allow you to change the slot, but only the drive and I need to start from a working drive.

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Copy II+ has a drive speed

Copy II+ has a drive speed option that does allow you to pick different slots if needed.

 

Either way, I'm still curious about the actual drive speed if you have done the test looking at the hub pattern, since you don't seem to trust the head and these types of speed tests. 

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nick3092 wrote:Copy II+ has a
nick3092 wrote:

Copy II+ has a drive speed option that does allow you to pick different slots if needed.

 

Either way, I'm still curious about the actual drive speed if you have done the test looking at the hub pattern, since you don't seem to trust the head and these types of speed tests. 

 

I did the hub test at 50 Hz by setting the shutter of the mobile phone camera to 1/50 (not having fluorescent light). Unfortunately I don't see a constant pattern in the 50Hz circle. Unfortunately, the trimmer allows you to refine the adjustment but with very low tolerances. In my case there seems to be too large a tolerance that cannot be adjusted with the trimmer.

 

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Assuming that method is valid

Assuming that method is valid, then that narrows it down to the belt or the motor. Easiest thing to try next would be a new belt. 

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nick3092 wrote:Assuming that
nick3092 wrote:

Assuming that method is valid, then that narrows it down to the belt or the motor. Easiest thing to try next would be a new belt. 

 

 

The belt would seem tight and ok. I might try another one anyway

 

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The rubber will go hard over

The rubber will go hard over time and develop slippery spots.

 

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can the head alignment disk

can the head alignment disk be replicated using kryoflux?

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 dorkbert wrote:can the head

 

dorkbert wrote:

can the head alignment disk be replicated using kryoflux?

No. Only a reference drive can create one.

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jeffmazur wrote: dorkbert
jeffmazur wrote:

 

dorkbert wrote:

can the head alignment disk be replicated using kryoflux?

No. Only a reference drive can create one.

Would it be possible to use one of the alignment disks to perfectly align a drive that could make new ones?

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 nick3092 wrote:Would it be

 

nick3092 wrote:

Would it be possible to use one of the alignment disks to perfectly align a drive that could make new ones?

Not perfectly. But if you can do this the resulting disks would certainly be quite useable for aligning other drives.

 

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jeffmazur wrote: nick3092
jeffmazur wrote:

 

nick3092 wrote:

Would it be possible to use one of the alignment disks to perfectly align a drive that could make new ones?

Not perfectly. But if you can do this the resulting disks would certainly be quite useable for aligning other drives.

 

The utility "APTEST" uses an ingenious comparison method to align drives against a known-good diskette.  

The key is that you need a diskette that you are certain was written from a well-aligned drive.  Preferrably some sort of (non-copy protected, preferrably) commercial software.  In my case I use a few Apple system master diskettes for this.

 

APTEST checks track positions (and half track positions) going both ways on various points on the diskette.  It then returns a readability score and scores for track positioning.  Based on those scores you can make changes to the stepper motor position to get to a decent alignment.  It's not perfect, but if repeated several times you can get almot perfect alignment using APTEST.    You can find a copy of it here: https://macgui.com/downloads/?file_id=9611&keywords=aptest

 

Warning:  be sure to read the directions carefully.  You can make disk drives much worse than when you started if you do these adjustments incorrectly.

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baldrick wrote:jeffmazur
baldrick wrote:
jeffmazur wrote:

 

nick3092 wrote:

Would it be possible to use one of the alignment disks to perfectly align a drive that could make new ones?

Not perfectly. But if you can do this the resulting disks would certainly be quite useable for aligning other drives.

 

The utility "APTES

Really good suggestions, especially on using something like that DOS SYSTEM MASTER floppies as a reference disk.

 

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What could a specific head

What could a specific head alignment software be? Also I would like to know if there are any video tutorials showing how to proceed ...

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GianDO wrote:What could a
GianDO wrote:

What could a specific head alignment software be? Also I would like to know if there are any video tutorials showing how to proceed ...

See my post above about APTEST.

Instructions on how to use it are embedded in the software.

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nick3092 wrote:The reason I
nick3092 wrote:

The reason I say that is I'm pretty sure these drive speed programs work by writing a piece of data and then timing when they see it again, and run a formula to roughly estimate speed. If the head isn't reliably reading, it could give false data.

 

 

You were right if the head is not aligned, the SpeedTest software does not work correctly giving wrong values. I was able to fix the rotational speed issue using a laser tachometer and it seems to be ok. Now I would like to solve the head alignment problem.

 

 

 

 

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baldrick wrote:GianDO wrote
baldrick wrote:
GianDO wrote:

What could a specific head alignment software be? Also I would like to know if there are any video tutorials showing how to proceed ...

See my post above about APTEST.

Instructions on how to use it are embedded in the software.

 

 

APTest I know and have used it before, but is there a better one?(Commodore has more support for this type of problem ..).I would like to be able to fix this Diskduo in all ways.

 

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GianDO wrote:APTest I know
GianDO wrote:
APTest I know and have used it before, but is there a better one?(Commodore has more support for this type of problem ..).I would like to be able to fix this Diskduo in all ways.

 

There is no better alignment method for the average user than Aptest unless you have a special alignment diskette, an oscilloscope and the appropriate diagnostic software.

Problem is that finding appropriate original alignment diskettes in good condition is difficult, not everyone has a good oscilloscope and even fewer of us have the know-how to put it all together.

 

 

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