Ok, works fine now as much as I could test it (I've formatted, written, read almost 50 different disks by now, including a few of my old C64 disks). It was not quite the pressure of the top head, but rather it's position with respect to the disk surface. I've noticed that moving the spring to the left would result in better read/write performances, while moving the spring to the right would result in no read/write even of the bottom head, so I've gently and lightly twisted the top head mount anti-clockwise and that solved all problems. This unit now formats all the good media I've found free at home and can write to them, as well as to C64 media formatted by three different 1541, and of course reads well all the 1541-written media. Patience helps, and observing well what's doing (after understanding what it is supposed to do). I don't suggest to blindly trying upsetting the spring and head mount if not really sure that the problem lies there, it would only make matters worse. I've first made sure all the head lifting and loading mechanism were free, lubricated and working correctly, and I've tested all the head wires to be working from track 1 to 35 before deciding to identify a possible head position problem. Thanks all for the suggestions. Frank IZ8DWF On Thu, Dec 21, 2017 at 9:26 AM, Francesco Messineo <francesco.messineo@gmail.com> wrote: > On Thu, Dec 21, 2017 at 9:17 AM, silverdr@wfmh.org.pl > <silverdr@wfmh.org.pl> wrote: >> >>> On 2017-12-20, at 14:32, Francesco Messineo <francesco.messineo@gmail.com> wrote: >>> >>> Hi all, >>> is it just me or there isn't a clear way to check and adjust the >>> spindle speed on an internal drive of the 128D? >> >> Adjusting may be tricky but checking can be done for example by using a strobo-pattern similar to what's been standard on earlier 1541 mechs. Or if your drive can still read, you should be able to run a small prg that verifies the interval a specific sector's sync mark is detected. I remember I once wrote (actually rewrote with timer adjustment) something like that for 1541. > > I've tweaked a bit the pressure spring on the top head (side 2), the > drive now formats and reads (still marginally, but directory is always > ok) the 1541 disks, so side 1 works. Side 2 still doesn't format > (well, it formatted once in 20 tries) and doesn't read. > I think it's the top head position that's wrong. > When formatting a double side disk, this firmware makes the first 35 > tracks on the side 1 (bottom) then seeks back to first track and > formats the side 2 35 tracks. When seeking back for side 2, it usually > stops formatting. > Wirings on the top head seems ok, but I'll check also that. > Thanks > Frank Message was sent through the cbm-hackers mailing listReceived on 2017-12-21 12:00:03
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