I have a C5+ of unknown vintage. There was no declination drive with it. I'm an electronics design engineer and have done some experimenting. Supposedly, on my scope, there is a "high" speed function to RA and DEC. Hold down the button on the hand controller for the direction desired and you get "slow" correction. Press the opposite button (while continuing to hold the first button) and the unit shifts to "fast" correction. My unit definately does not do that. The RA drive works fine. I bought a MotoDec from JMI and it plugs into my base. It looks like it will install easily, but when I activate the control, the motor grunts and doesn't move. I have looked at the drive signal with an oscilloscope and I see that the signal pulses 0 to +5 or 0 to -5 volts depending on direction. It turns on for .5 milliseconds and off for 1.0 milliseconds. The frequency of the signal is about 666Hz. That's way too fast for any conventional motor I know of. It won't turn a little 1.5 volt hobby motor with no load. I sent my findings to Celestron and they were surprised with the level of information I sent them. I got the impression that I now know far more about this than they do! They can't tell me anything about this. I am EXTREMELY dissapointed at their lack on knowledge about their products. This is not a comodity. It is supported almost completely by amateurs. I cannot believe that they can be so uninvolved. I am also trying to contact the elusive Rick at Tangent, but so far no luck. I will trace out the schematic of my board (which I suspect is not typical of all boards) and post it for your reference.

• schematics available? - delyan - October 1, 2004 - 14:06 UTC