Hi all,
I stumbled across this when I was lubing my 8"LX200 RA drive.

The drive base bottom cover was open when I switched the thing on and off a
few times already and all was ok.

Then once, when I switched it on, the DEC motor began running at full speed,
(DEC was unclutched) the keypad display started up as normal, and i think
all buttons except for N and S worked normally. N and S did not produce any
response. i.e. DEC continued to run, till I switched the scope off.

I switched it on and off a few times and I think this repeated a few times
(DEC ran crazy whenever switched on) until something changed... this time it
was the RA that ran crazy when switched on. everything else was the same. (E
and W buttons were disabled)

Swearing and sweating away, I turned the scope on and off a few more times,
checking around in side the drive base.. until it reverted to normal...
(sigh of relief) At this stage, I still did not know what went wrong.

Then when I was reinstalling the drive base cover, (power was on) I noticed
that touching the small metal piece which conducts heat to the cover,
sometimes caused the motors to run. (when improperly positioned.)
Apparently, there are some resistors and thingies under the little metal
plate which can be shorted by the plate. The plate had been dangling loosely
in place throughout by the stickiness of the heat conductive paste, and
resting on the central hole of the drive base.

Ok, anyway, here's what I've learnt:

1. The small metal plate, when improperly positioned, can short the
resistors under it and cause the DEC or RA motors to run on their own.

2. I needn't remove 2 of the hex screws which fix the small metal plate to
the 2 hot components on the mboard, in order to open the cover. (It is
necessary to undo the lower 2 hex screws which fix the plate onto the
cover.) Would have made life much easier if I had left the metal plate
screwed to the 2 components.

Hopefully, nobody has replaced motherboards or DEC drives just because of
this...

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