JONATHAN@NUACC.ACNS.NWU.EDU (01/07/90)
I have a friend with an old DISK II 5.25" disk drive. The disk drive claims that all disks inserted are copy protected. I have checked the sensor and it does not appear to be the problem. I tried both opening and closing the circuit with and without the switch in the circuit. Does anyone have any other suggestions on how to fix this problem or what the problem may be? Thank you, Jonathan Gelfand
greyelf@wpi.wpi.edu (Michael J Pender) (01/10/90)
In article <F9E2DD08F5DF00202F@nuacc.acns.nwu.edu> JONATHAN@NUACC.ACNS.NWU.EDU writes: >I have a friend with an old DISK II 5.25" disk drive. The disk drive >claims that all disks inserted are copy protected. I have checked the sensor >and it does not appear to be the problem. I tried both opening and closing >the circuit with and without the switch in the circuit. Do you mean it says disks are WRITE PROTECTED? Copy protection is another bunch of trouble entirely.
sb@pro-generic.cts.com (Stephen Brown) (01/13/90)
In-Reply-To: message from JONATHAN@NUACC.ACNS.NWU.EDU Jonathan Gelfand asks about a Disk II that insists that all disks are write protected. Some Disk II clones use photoelectric sensors instead of mechanical (micro) switches. I have a Quentin Disk II clone which had a bad infared LED which caused it to think that all disks were protected. A replacement LED came from Radio Shack for about $4. If the drive has a mechanical switch, it can be tested with an ohmeter. According to the schematic for the Disk II analogue board (which appears on page 146 of the DOS manual), the Write Protect signal comes from phase 1 from the disk controller (generated by the 9334/74LS259 on the Disk Controller card -- probably okay) and ends up going through one part of the 74LS125 on the analogue board -- probably the the problem. Why not take a logic probe to pin 2 of the 74LS125. If opening and closing the write protect switch causes this to go up and down, then check pin 3 of the 74LS125. If pin 3 is following pin 2, then your cable is bad. If pin 3 is not following pin 2, then the 74LS125 is bad. If pin 3 is not following the switch (and the switch is okay), then I'd suspect the cable or the 9334/74LS259. Howzdat? UUCP: crash!pro-generic!sb ARPA: crash!pro-generic!sb@nosc.mil INET: sb@pro-generic.cts.com