On 8/15/2015 8:31 PM, Jon Elson wrote: > > On 08/14/2015 02:58 PM, Jay Jaeger wrote:
No, I didn't write any of what was quoted. ;) If one is going to remove the entire message quoted, then it probably makes sense to delete the "wrote" line as well. ;) > > The way most of the old 8" floppies work is they have a cylinder with an > ID that matches the ID of the floppy hole. The floppy sits against the > face of the cylinder, and a plastic, springy cone is pressed into the > cylinder by a bearing and spring on the loading arm. This arm usually > also lifts the head off the media when in the open position. > As Tony discovered after checking one of his own SA-800 series drives, that is not how the SA-800 series works. In these drives, the spindle is NOT a cylinder. The spindle is a CONE on top of a flat part (all one machined piece), then a shaft through the deck, to the pulley on the other side. The media sits on the flat part , just below the cone, and the plastic springy CYLINDER (more or less), gets pressed OVER the cone and on top of the media over the flat part. > So, the first thing to check is if the plastic springy thing still has > all its fingers. If fingers have broken off, the result is obvious. If > all the fingers are still there, check for smooth sliding into the > cylinder. If the fingers have gotten bent or rough, the clamp may not > always seat reliably against the hub. > Had you read the whole thread, you would have read that I had already examined the "plastic springy thing" (aka, the hub clamp), and found it to be healthy, and HAD ALREADY SWITCHED IT WITH ANOTHER hub clamp THAT WAS on a working drive with no change to either drive. > Finally, the spring or bearing may have a failure, not driving the clamp > into the spindle. > The hub clamp is engaging onto the spindle just fine, thank you very much. There is no bearing of any real import in the hub clamp, really, just a screw through (perhaps) a little straight bearing. The spring in the hub clamp is obviously fine (and, again, it had been part of the assembly I switched with another drive). > Almost certainly, careful examination of these parts will reveal the > problem. No, careful examination most certainly did NOT reveal the problem. At this point, the best guess is either that the clamp arm is out of true (unlikely), a grove that cuts into the cone at its bottom, allowing the media to shift, or a spindle problem (bearing, not the correct shape any more, etc. etc.). > > Jon > JRJ
