William Levak wrote: > The stepper motor is connected to the Commodore system board through this > circuit board. No, Bill, it's the spindle motor. The stepper motor is always connected directly to the drive's main board. > Nicholas reports that on his 1541C drive there is a track 0 sensor that > gets it's power from the Commodore system board, but connects the output > signal to the stepper motor board. I didn't say this. I said that the WP LED is connected to the spindle motor control PCB, and it was on the Chinon drive. > This makes sense because none of the 1541 ROMs and none of the Commodore > system boards provide support for a track 0 signal. 250448 has an input for the track 0 sensor, it's mostly disabled by a short to GND (It was via J3, I think), but otherwise connected to PA0 of the bus VIA. The ROMs 251968-01 and 251968-02 have support for this signal. The 1541-II has the GND connection to PA0 left to enable this board to work with the two above mentioned ROMs. But the drive was only shipped with 251968-03 which had the sensor support removed. > If the track 0 signal > is connected to the stepper motor board, then it can turn off the stepper > motor at track zero without any active support from the Commodore System. I'd really love to see this solution in any Commodore drive. But I never did. BTW, my SFD1001 also has a track 0 sensor, but doesn't make use of it. Neither in hardware or software. > It appears then that the same Newtronics D500 drive mechanism is used on > all 1541 drives, only with different connectors and the track 0 sensor > removed on some. I agree with you here, but the sensor probably doesn't have to be removed. Like on my 250442 board, where there's simply nothing useful connected to the track 0 sensor pins. > This would also mean that the drive mechanisms should be compatible > across all the 1541s if you change the connector. This is true. Nicolas - This message was sent through the cbm-hackers mailing list. To unsubscribe: echo unsubscribe | mail firstname.lastname@example.org.
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