I'm working on applying the same principles as the HDDLW to retrofit high-density support to old Acorn Archimedes systems, and while experimenting with drives in my junk drawer, I came across a variant of the Teac FD235HF that does not appear to be suitable for this modification: the FD235HF-4240 has a 10-pin (rather than 11-pin) connector to the motor board, and the motor controller's OSC1 and OSC2 pins are connected to a crystal on the motor board (Y61 in my example), rather than having OSC1 driven by a clock from the main IC.
Aside from the -4240 model suffix, the other distinguishing feature of this variant is an unusual blue-coloured external layer on the main PCB. Never seen that before.
While I'm here, I might as well also add that the Sony MP-F17W doesn't seem to take well to this modification either. Though it has a convenient 0-ohm resistor that makes it easy to interpose the motor clock, the motor has fewer slots than most others I've seen, and at half speed, you get visible torque pulsations (and some pretty horrible noises). No bueno.
I'm working on applying the same principles as the HDDLW to retrofit high-density support to old Acorn Archimedes systems, and while experimenting with drives in my junk drawer, I came across a variant of the Teac FD235HF that does not appear to be suitable for this modification: the FD235HF-4240 has a 10-pin (rather than 11-pin) connector to the motor board, and the motor controller's OSC1 and OSC2 pins are connected to a crystal on the motor board (Y61 in my example), rather than having OSC1 driven by a clock from the main IC.
Aside from the -4240 model suffix, the other distinguishing feature of this variant is an unusual blue-coloured external layer on the main PCB. Never seen that before.
While I'm here, I might as well also add that the Sony MP-F17W doesn't seem to take well to this modification either. Though it has a convenient 0-ohm resistor that makes it easy to interpose the motor clock, the motor has fewer slots than most others I've seen, and at half speed, you get visible torque pulsations (and some pretty horrible noises). No bueno.