30 Jul
2002
30 Jul
'02
8:40 p.m.
On Sat, 27 Jul 2002, Tony Duell wrote:
Interesting. Maybe the lock is not releasing. Or maybe
the heads are
being rammed into one end stop due to the lack of servo signal from the
heads. But how come the drive voltage is so low?
I don't hear the heads move much at all. It sounds like they are trying to
load, but just don't move. I don't hear any of the typical sounds I hear
from other drives when their heads load.
Have you traced out the connections to the connector
you think is for a
positioned lock? On the V150, one pin is grounded. The other goes via a
power transistor to +123V (MJE210, PNP) to pull the solenoid in, and via
a resistor and annother MJE210 transsitor to +12V to hold it. Does that
sound similar?
If this is the head lock solenoid, do you get any voltage across it when
the drive is attempting to spin up?
I think I did get voltage on that connector when it seemed to pull in.
I'll have to double check though.
A silly test, but one worth doing. The V150 uses a
diode/capacitor
circuit driven (indirectly) from the master clock to generate a -ve
supply voltage to the op-amps. If it malfunctions, all sorts of things
will malfunction (both because of the missing supply and because a
protection circuit will clamp signals, etc). Can you just check the
voltage at pin 4 of some of the 4558s?
I'll certainly check it.
Unless you have a clean box, I would do a few more
checks outside the
HDA first
Well, ok :P
-Toth