PDP 11 - how to lock heads in a rx01 and rx02 - seeking advice

tony duell ard at p850ug1.demon.co.uk
Sun Jul 12 23:42:31 CDT 2015

> Very good explanation, Tony!
> Is there any chance that he might need to worry about a pack being inside the drive with the heads un-parked, e.g. > from an abrupt power failure?

I would hope not (IIRC all DEC drives are designed to retract heads if the power fails). If the heads are still
loaded and the drive has spun down then both heads and pack are likely to be damaged.

However, it can't hurt to check.

After removing the rear cover and top door, if there is a pack in the drive,  then before trying to remove it,
lift out the read/write module, which is the central part in the rear section of the drive. It has a ribbon
cable to the PCB in the cover and 2 cables on the underside to the heads. After lifting it up you'll
see the heads. Make sure they are as far towards the rear of the drive as they will go. If not, very gently
slide the head assembly that way. Then remove the pack as before and lock the heads.


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