17 May
2010
17 May
'10
12:17 p.m.
Yes "blipping" the coil with a 9V battery moves the heads. When the drive
was powered on I also measured the voltage by attaching a probe to each end
of the coil cable, in that case I measured about 1.3V only. So I am guessing
the coil is OK. Next step is to swap the boards back again.
And then fix the real fault :-)
More seriously, it sounds like the positioner coil is not being driven
hard enoguh to move the heads -- and if the coil was open-circuit I would
ecpect the servo sysem to try to drive it very hard to attempt to get
some movement. Normally there are various conditions which have to be
satified (motor up to speed, no write current unless write gate is
asserted, only one head selected, etc) before the heads will move. It's
entirely possible the problem is in one of those areas.
-tony