Wednesday, December 14, 2011

The Crystal Arrived - the quest for Mark-X motor

The stamp reveals that it comes from Thailand, it's well packed and in great shape.

With some careful observations, I've cut off the old crystal which is longer and bigger in size.  I've carefully bended the legs of the new crystal and try to fix it in place with a tape.  Then I proceed to solder it in place.  It's not an easy job since the legs were in a rather crowded place.  I tried to melt a tiny ball of solder and then dip the whole ball into the joints.

After the soldering work, I switched on the power to check the time required for a complete rotation, it should be longer than 8 minutes (180 teeth with the original crystal) and it's hopefully 11 minutes and  25.7 seconds (126 teeth with the new crystal), but I know the speed will be slightly different since the crystal is not really 3.68MHz but 3.6864MHz.

With my best effort timing, the time required for a full rotation is now 11:10s.

After adjusting the trimming capacitor for two clockwise turns, the time for a full rotation is then 11:22s.

And the third adjustment yields 11:26s... and I won't adjust it further, since my timing method should not be accurate enough to be meaningful.

Still need to wait for the shaft coupler, and then I shall attached this motor to the mount for a real test under the stars!


Original crystal carefully removed:-

New crystal placed in location:-

Ugly soldering job done:-

Updated 2011-12-16 (afternoon):-

The source of this motor is pretty good, the seller said he has more than 50 pcs in stock.  Thus, I won't bother to buy backup at the time being.

When I go out to work this afternoon, I found that shaft coupler was already in my mailbox, it's very nicely machined with light weight but thick aluminium.

On the way to office, I have bought several M6 screws, nuts, and a small stainless steel mounting plate.  And I guess I shall be able to fix them together.  Hopefully I won't need to drill any holes except to enlarge a few holes by tapping.

 Updated 2011-12-16 (night):-
The shaft coupler gives a perfect fit.

The M6 screw for the mounting hole on the Mark-X fits very well, too.

The M6 screw for the motor fits excellent as well.

But that small mounting plate needs bigger hole to accommodate the M6 screws but then it's harder than I imagined, so I will need to enlarge the holes tomorrow with a drill. Can't do it tonight since I've no drill on hand.

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