Posted By
crock
on 2011-11-27
15:44:32
 |  Is there any 1551 head alignment or rpm tools?
I have two 1551's which exhibit the signs of being badly adjusted wrt alignment or speed. Is there any plussy tools to help me diagnose or adjust?
I could resort to pulling the mechanism out and dropping it into a 1541 if needed but thought I should ask first...
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Posted By
TLC
on 2011-11-28
04:23:32
| Re: Is there any 1551 head alignment or rpm tools?
I'm not aware of any. But I also haven't heard that the drive mechanism in the 1551 was prone to head alignment problems. (AFAIK head alignment was only ever a problem with ALPS' drive mechanisms). From the other hand, only late 1541-II drives were equipped with direct drive mechanisms; consequently, checking if the (some 25 years old) drive belt hasn't worn out yet, might probably be reasonable (and simple).
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Posted By
crock
on 2011-11-28
04:52:15
| Re: Is there any 1551 head alignment or rpm tools?
I think the problem here was that the muppet who sent me the 1551 made no effort to pack it well. It was in a flimsy cardboard box with some crunched up newspaper. The C16 PCB that was included was just placed on top of the drive and so the component pins have scratched the 1551 case terribly.
It was also crushed hard enough to break the grill on the top and smash the screw receptacles right out of the case, so a lot of superglue has been required to get a useable case. It's no surprise that the mechanism has also taken a beating with this kind of treatment.
After I posted this I took the mechanism out and attached it to a 1541 board to check it. I managed to get it back into alignment but the stepper motor has been rotated all the way to one extreme. I can only assume that the rough treatment has bent something. Although the drive now works it's not much good for much more than spares. Mayble I'll spray paint a 1541 case and transfer the board into that!!
I'm really annoyed with myself for not doing this after I took delivery, then I might have some comeback on the idiot who sold it....
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Posted By
TLC
on 2011-11-28
10:31:34
| Re: Is there any 1551 head alignment or rpm tools?
Some people just deserve to be shot to hell. OMG! Now I understand how it could just go "out of alignment" (...kind of an understatement for this case)...
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Posted By
SVS
on 2011-11-28
14:08:23
 | Re: Is there any 1551 head alignment or rpm tools?
Try this:
http://plus4world.powweb.com/sd.php?pid=12879
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Posted By
Chicken
on 2011-11-30
13:42:27
 | Re: Is there any 1551 head alignment or rpm tools?
I had a couple of DOAs, too, due to careless packing  Sure, the 1551 case's plastic is a bit different from the 1541 one ... more brittle. But carefully packed it should survive shipping to almost anywhere. Some years ago I shipped one to Hungary and if I remember correctly, it got there in one piece.
Most 1551 cases I have seen are not 100% perfect anymore, though. Usually, the corners of the top cover are chipped off.
How did you realign the drive? I have one mechanism which failed years ago. I'm not sure if it's just misaligned or if the read/write head is completely defunct.
Transfering the 1551 board and drive mechanism into a 1541 case might be an option but it's not really perfect (e.g. IEC-port holes).
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Posted By
crock
on 2011-12-01
09:57:42
| Re: Is there any 1551 head alignment or rpm tools?
I attached the mechanism to an old 1541 and used the FreeSpirit drive alignment program on a C64. You need to rotate the stepper motor slowly and look for good alignment to half tracks.
It's not too difficult when you get the knack of it. If you think the mechanism is trashed, check the resistances across the wires to the read/write head. It should be between 12 and 25 ohms across any combination, anything significantly higher means the head is toast.
Rob
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