09-21-2015, 08:20 AM
(08-31-2014, 10:36 AM)admin Wrote: Here is a datasheet with numerous 5.25" drive's jumper settings.
5.25" drive jumper settings
I acquired a Kaypro 4/84 which is equipped with DSDD Epson SD-521 drives. This is an odd drive with a"push button" mechanism and I can't find documentation for it. But the reason for writing is that in testing the drives with the SCP I found the following:
The Kaypro floppy cable is not twisted, so A drive is jumpered to DS0 and B to DS1. Except for this difference both appear to be the same. A drive reports as D0 to the SCP, shows the maximum track as 42, performs the speed test (approximately 300 RPM) and erases and tests media. B drive reports as D1 to the SCP, responds to the max track test, does not perform the speed test and reports it can not find the index sync.
It can't find the sync pulse because the motor does not spin. When the B drive is connected to 12V power but NOT connected to the SCP via the twisted cable, the motor runs indefinitely. This is not the case with the A drive. When drive B is powered with 12V and the twisted cable is connected to the B drive its motor does not run, whether the SCP is powered or not.
In other words, A drive spins but only on command from SCP, while B drive spins only while not under command from SCP. It behaves this way whether jumper DS0 or DS1 is selected. There must be some configuration difference but I can't see it and I can't find any docs. Do you have any suggestions?