FD400 drive troubleshooting

Incidentally, I asked a friend wbo is both a classic computer enthusiast and a musician if there would he any audible difference between playing the record at 45rpm and at 45.11 rpm. He said he didn't believe anyone could tell them apart. So I susepct the only people this matters to are the audiophools. Actually I am suprised nobofy has tried to sell said audiophools a crytal-controlled lamp to view the strob disk with. Or amybe they have and I've not noticed it yet. It's hardly 'my method'. I certainly don't claim to have invented it, but alas I can't find a reference to it. I am not sure when stroboscopes were invented, I susepct they pre-date electricity, though. Certainly stroboscpinc tuning forks exist -- these a tuning forkes with slotted vanes on the tines (they are designed to have the extra mass of said vanes, of course)< you view the stroboscopic disk (or wahtever) through the slits. To make this marginally on-topic,such tuning forks were used, at least in the UK, to set the speed of teleprinter motors. Creed teleprinters have series-wound motors with a governor assembly on the end of the motor, and you viewed the black and white stripes on the governor cover through such a tuning fork. Somewhere I have a trleprinter test set (an ATE (manfufacturer) TDMS5 if you know about such things). The master oscillator not only drives the ring counter that acts as the transmit distributor (the whole thing is valved, BTW), but also a neon lamp on the panel. You are supposed to view this lamp trhough one of said tuning forks and effectively 'zero beat' the bulb agianst the fork to get the oscillator on-frequency. One other thing to be aware of. The ideal strobosope has very narrow flashes of light with larger gaps between them. If you are using a 'harmonic disk' (or whatever you want to call it), you need to get closer to this ideal than for a normal disk (at leat to get a very clear pattern). Of coure a real xenon-tube strobe does this, a mains neon bulb may not. -tony