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ΛΛdZ
Registered: Jul 2005
Posts: 153 |
Drive alignment
I have some problematic 1541's which I have tested on speed and alignment, with various old tools. Drive-speed was easy to fix but alignment is a bitch to control and adjust! I'm new in the area of fixing drives, so I need some experienced advise on tools to use and info on the techniques :)
Request: Tools (which you use with success) and info/text on how to fix the alignment!
Thanks! |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
you cant really align a drive properly without an analogue alignment disk, which is unfortunatly almost impossible to get (and impossible to duplicate by standard methods, they must be written with special machines).
there is supposed to be a way to do it with a known "good" disk (original, eg the test/demo disk), but i dont know the details... i only know how the proper way works =P
that said, forget ANY method that doesnt involve a reference disk and measuring with an oscilloscope. you'll only make it worse. |
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ready.
Registered: Feb 2003
Posts: 441 |
I recently bought from Amazon the book: Commodore 1541 Troubleshooting and Repair Guide, Google for it and get it, there are still available copies for a cheap prize. There are various method for drive alignment, but as Groepaz said the best method is to use an oscilloscope. |
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Conrad
Registered: Nov 2006
Posts: 849 |
There's also this:
http://codebase64.org/lib/exe/fetch.php?id=books%3Astart&cache=..
... read up on chapter 3 in the .pdf... hope this helps a bit. |
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ready.
Registered: Feb 2003
Posts: 441 |
yes same book.
It is interesting to notice that on page 172 there is a warning against permanent damage to the drive 1541 which can be done via software:
Never write to memory locations at or above $8000. A bus conflict may occur, causing permantent damage to UB3,UB4 or UC4.
I didn't know that.
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Devia
Registered: Oct 2004
Posts: 401 |
Check my post here: http://noname.c64.org/csdb/forums/?roomid=7&topicid=39351#40037
As you can gather from that post, I'm not quite in agreement with Groepaz in regards to using a scope.. It really is a matter of preference and/or skill. With a bit of excersice and understanding of the drive mech, adjusting a mech to match the alignment of another mech close enough for error free operation is not that difficult. The important thing to keep in mind here though, is "DON'T TOUCH THE ALIGNMENT IF IT AIN'T BROKEN!" - then you'll just risk ending up with a set of drives in alignment with eachother, but not the rest of the world ;-)
If you use so called "original" disks as reference disks, be sure to test with several before setteling on _your_ reference, since many "original" disks are actually not all that well written.
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Mace
Registered: May 2002
Posts: 1799 |
Come to X-2008 and I'll bring my set of alignment disks :)
Nope, sorry, not for sale. |
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Graham
Account closed
Registered: Dec 2002
Posts: 990 |
I once tried to align a mech and after hours i gave up. Occassionally I was able to load a dir, but I never came close to a good alignment. |
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Mace
Registered: May 2002
Posts: 1799 |
It's a painstaking job and it requires patience and a steady hand.
I managed to fix a drive without prior experience, so it CAN be done. |
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maestro
Registered: Mar 2004
Posts: 727 |
well if there not for sale mace how about some images of them so we can put them onto disk ourselves :) |
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chatGPZ
Registered: Dec 2001
Posts: 11386 |
read again what i wrote before :) alignment disks contain an _analogue_ signal. you cant make images from them or even copy them with normal drives. |
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