22 Mar
2011
22 Mar
'11
12:07 p.m.
Hi,
Well I had a crack at looking at the hall effect devices in the two faulty
drives. Under the scope, there didn't seem to be anything unusual. All
hall effect devices showed a similar AC waveform in all circumstances with
nothing appearing unusual or very different about any of them?
I wonder wht the problem is, then.... I suppose it's possible that
soemthing is damaging the contoller IC as soon as you try it. The obvious
candidate for that would be the damping capacitors, but you've changed
those. We know, I think, that the motor windings are not open or dead
short, but I wonder if a shorted turn in one of the windings could damage
the contorller IC.
Although it would be good to know exactly what was wrong, further diagnosis
is no longer necessary. John Woodall, whom I bought the X\Profile card off,
has generously sent me a replacement drive (and a couple of spares), for the
cost of shipping only! THANK YOU John.
I tried them two of them out yesterday and they are fine. My two Lisas are
now up and running.
Words like 'wimp' and 'boardswapper' are going through my mind :-).
I guess that's where I differ from many people here. I don't just want
working classic computers, I want to know how they work, and I want to
know how to really cure any faults I come across.
-tony