Most ‘real’ alignment disks are written on special drives that are not only very, very precisely calibrated but they can also vary the angle of the head. This angled write somehow enhances the ability to detect alignment issues with the use of an oscilloscope monitoring the head output (don’t remember the exact reasoning off the top of my head.)
At some point I found a blog where someone described aligning a TPDD by adjusting the position of the home sensor. He just small very small changes tried to read a disk, made another small change, etc. On the C64 drives I use commercially produced disks, which are made on fancy duplication machines that were kept well aligned. There is C64 software which can tell you how close the alignment is (it microsteps the head as I recall so it can find at which microstepped position the signal is highest by less garbled data I would guess). This works well and can get you close enough for the drive to work very reliably. On the TPDD it might also help to use a commercially produced disk as there is a much better chance it was written on a duplication machine that was more precise. As original disks seem to be as rare as hen’s teeth these days you might be stuck with trying to read a variety of disks written on other TDPPs. Jeff Birt From: M100 <[email protected]> On Behalf Of Stephen Adolph Sent: Saturday, April 3, 2021 7:00 AM To: [email protected] Subject: [M100] TPDD alignment disk / servicing / MICTDC Now that we have the official service manual for TPDD, I am wondering if anyone knows something about the alignment disk. It seems like the alignment disk is needed to adjust the track position. Can we use a "stock disk" for this as well? Maybe the alignment disk is an idealized signal with a golden alignment, but seems like a factory disk might do as well. The document also mentions MICTDC program which was provided on a tape AXX-2049. Anyone have that cassette or program? ..Steve
