tom@wcc.oz (Tom Evans) (11/02/90)
I was over at a friends place on Wed. night trying to get his old Rainbow working. The RX50 wouldn't reliably read some floppies. Firstly, it was running at 240RPM, when I'm sure that it should've been running at 300RPM (just a simple turn of the motor speed pot). Then it would read some disks and not others. Eventually we found that some disks weren't generating index pulses. It was due to the index photo-sensor - not an unusual problem. The shock came when we found that the problem wasn't due to the photo-sensors not seeing the HOLE in the disk (an expected problem), but due to them not seeing the DISK. Yes, the disk media on some of the disks is TRANSPARENT to the infra-red light used by the sensors, so the drive sees nothing but HOLE. The disks are transparent enough that you can see a torch through them. These are original DEC distribution Rainbow floppies too! We were able to make the disks readable by "painting" on the disk with a black "texta" pen through the index hole in the cover (bleah!). Were there any Engineering changes to make the sensors less sensitive that anyone knows of? Anyone else have problems that sound like this? For anyone wanting to check, the "test point" is the blue wire going from the photo-sensor to the rear PCB on the drive - grab it with a scope probe on the connector. Please mail any responses to me (as well as to the group) as I don't read this group often. Thanks ======================== Tom Evans tom@wcc.oz.au Webster Computer Corp P/L, 1270 Ferntree Gully Rd Scoresby, Melbourne 3179 Victoria, Australia 61-3-764-1100 FAX ...764-1179