Commodore cbm 8250 lp drive heads

    I have been restoring a CBM 8250 LP and noticed that the drive heads were different colors. Drive 1 was the usual cream Color but drive 0 was a brown Color as in the photos. I lucked in to a cheap other LP and that drive also showed the same. The later were JU-570-2 whereas the first drive are JU570 drives. Is there any reason why the head would go this Color or was this just batch to batch variation in drive builds ?


    Drive 0 in the first lp was faulty… the lower head read disks ok but the upper head was either out of alignment or defective (using the 8250exam disk routines).


    To switch from 8250LP to "8050LP" you have to cut solder jumper E3 (located at D1) and E4 (located at B1).

    Cutting E3 disconnects the head select line.

    E4 connects UAB3 (6530) PB6 (pin 18) to GND.

    During reset, the firmware checks this connection to decide between 8050/8250.

    E4 is not available on some board revisions, so you may just bend the pin out of the socket.


    Switching the 8250LP to 8050 through E4 is barely documented, and I never tried this out.

    So please let us know, if this really works.


    Maximize the picture to see the my lettering E3 and E4 (red, left edge of the picture).

    Thanks … just found E4 link on the 8296 drive drawings ….. will give it a go and report back. Just finishing off the LP and will swap out the motherboard for one which has the solder link removed.


    Incidentally, I added a switch to my full size 8250 so it could switch between 8050 and 8250. I know you can do it in software but have to reload every time the machine is reset.