I'm trying to write some disks using adtpro and I keep getting a "This disk is write protected" error. I used the other drive and same issue, and I know that one works. I've gone in with a q tip and some isopropyl and cleaned the inside of the rail, but no luck
I'm thinking it's a software issue
Make sure the diskette is not write-protected due to a sticker over the notch:
WriteProtected.png
20251007_220037.jpg
What happens when you simply format the disk with ProDOS 2.4.3's CopyPlus 8.4?
Nice DS diskette by the way. Back in the day I used to cut the notch on the other side with scissors. :)
I often used scissors as well! Got to where I could do it and it was hard to tell it wasn't done with the fancy tools you could buy back then. Back in the day I used to have litterally thousands of floppies. I still have a few hundred around here.
Can't format the disk, gives the error
I haven't seen someone suggest this but I bet the write protect switch on the inside of the drive has failed or is stuck. I'd check that to see if it stuck closed. My Atari drives had LEDs and we'd bypass the Write protect at the LED (usually to provide Write protection even if the disk had no write protection). According to the schematics (which don't show the switch) there are electronics that could have gone bad.
If you KNOW the drive itself is OK, then it's probably the Disk Controller at fault. There is an LS323 that handles the WRPROT signal from the drive. If you don't have another controller card to swap in, try replacing that chip.
I'm pretty sure it uses a censor, not a normal switch
On the original Disk II floppy drive it's a mechanical microswitch. You can hear it click as the diskette goes over it.
20251012_140312~2.jpg
Yes that's a sensor. But you can test that to see if it's always on or off. With no disk it should be on. Of course it could be further down the line as there are other electrocics involved. I haven't found a good schematic so I'm not able to help further as I also don't have any Apple Drives.
That's the one thing about the Duodisks/Unidisks i hate: There's VERY little documentation, which has made troubleshooting a real PITA
Can you provide a photo of the analogue card in your duo-drive.
If it is always write protected it could be 74ls125.
Check out this previous duodisk troubleshooting topic.
https://www.applefritter.com/content/duodisk-light-always-help-needed