Advice for tape drive repair / maintenance

[Tony Duell]

> Haven't seen any analogue hard disk drives recently...

I have, I own one...

It's a single-platter, multiple fixed head unit. The control electronics 
causes it to rotate (mains motor with disk+coil eddg current brake) at 
one revolution per video frame time, and video is stored on the disk 
using FM analuge recording (like the recording method used in a VCR). Of 
course it plays pack 3 trakcs simulateously to give colour (RGB) output. 

The verison I have is called a PPL 121 graphics system for the PDP11, and 
includes an FM modulator and contorl electronics that links to a DR11-B 
interface. I am told the technology originated in the 'action replay' 
recorders used on television.

-tony