14 Mar
2016
14 Mar
'16
10:52 a.m.
It's now foggy memory, but I'm pretty sure HP
7900A (and 7901) were using
batteries for emergency head retract.
The 7900 certainly does (there is one to go on my bench when I have some
spare time). In that case it's some AA-size NiCds (not tagged ones) in those
aluminium clip-in holders (Radio Shack used to sell them, I think Mouser still
do).
The DEC RK07 (and I assume RK06) used 8 1/2 AA cells in a pack (like
2 RK05 retract batteries in series). When I replaced those, I used 2 of
the cordless telephone batteries (that have been recommended for
the RK05) in series.
I am told some later drives used the spindle motor as a generator when the
power failed to provide the power for emergency retraction.
-tony