LGP-30 Memory Drum Update

On 01/04/2017 09:56 PM, Jon Elson wrote: Based on more than a few drums and disks i've seen its oxide, not plated. I'd also say if the scratches are not deep a little polishing may be the trick. I'D do nothing until it can be run up (remove all dust and gunk) and then look at the output of the heads. Likely you don't have to write clock tracks if there is mechanical (tone wheel). If so that means the clock is created there so its always in sync with drum rotation. That's one less headache. I have a hunch that the data/instruction tracks are not pre-recorded and can be over wrote and replaced at will but there is where the manuals and a thorough understanding of the machine and its logic is needed. IF the data tracks are created by other timing (clock and logic) then erasing a track is safe (check manuals) and then you can write a track with F and 2F and see if it reads out uniformly if it does that head is good and the media under it is. Step and repeat, any that fail or have to many drop outs or other errors need care, relocate first and try again. This is about what old school tricks need to be found out about and relearned. The closest analogy is how to steam and repair a coal fired locomotive. There is hand me down knowledge that will be needed and learned or even regenerated. A very interesting project. Allison