On Fri, 9 Feb 2018, js--- via cctalk wrote:
A tangential question out of curiosity: who here has 5.25" MFM drives they're extremely surprised are still working, and which model(s)? I'll start. I've quite a few MFM drives, but the ones that really surprise me are (2) Seagate ST-506, and (2) IMI CM-5412. My surprise is b/c these are amongst the earliest of models.
One factor may be that the earliest models were new attempts, and tended to be very carefully engineered, and often conservatively, due to lack of prior experience. On the later drives, they had "learned" and "realized" some of the corners that they could cut. "On analysis of failed drives from various problems, it is clear that none of the failed drives were even halfway through the life of the lubricants. Therefore, cheaper lubricants and smaller quantities with half the expected life would still be adequate to outlast, on average, the other components."?
I've performed *some* work on all these drives, such as cleaning and caps reforming, but haven't yet discovered a way to lube motors & bearings. I think lube issues will spell their ultimate demise.
One of the first corners to cut, once analysis of failed units from other causes shows that it is outlasting the rest of the unit.
In addition, of course, some lubricants can deteriorate, whereas many other components may have no significant impact from time. Lubricants can fail from contaminants that would not affect most other components.