Having done a fair bit of work trying to improve the motor drive for my EQ3-2 mount I wanted to look particularly at the DEC motor to see if I could improve its performance at all. It’s had a tough life and been repaired at least a couple of times, so a bit of TLC probably wouldn’t go amiss.
First step was to remove the cover and bracket and split the motor from the gearbox. The motor drive housing just slides off (image 2 below) which makes it easier to get to the screws holding on the mounting bracket.
Removal of the bracket (image 3) reveals three screw heads on the output shaft face that can be unscrewed to split the unit into motor, gearbox and mounting flange (image 4). It’s useful to note at this point the orientation of the gearbox and mounting flange as the entire drive won’t go back together if they’re wrong.
The gearbox was full of sticky black goop (image 5) that I removed with a brush and isopropanol, but even that was tough work. Not all of the grease would come off, but it wasn’t too bad in the end (image 6).
Testing the gearbox suggested there was quite a large amount of slop in the mounting of the first driven gear (the nylon one) which could rotate noticeably on its axle when then second gear was held still. I couldn’t see anything I could do about this problem without the risk of destroying the gearbox completely, so in the end I left it alone and just lightly re-greased the gears before reassmbling the unit.
Testing the motor afterwards it became clear that not only was there a significant amount of backlash, but also the DEC motor skipped on occasion, failing to turn smoothly. After much deliberation I decided to replace the motors rather than trying to fix something already running poorly. The first thing I did when I received the new motor set was to strip down the new DEC motor the same way and compare the two. You can see the much better condition of the new (uncleaned) gearbox here:
The slop in the first gear wheel was also about half that of my original one. I’d still like to reduce that if possible, so I may now attempt to dismantle the original gearbox as a test run to see if I can improve it. If I can then I’ll probably do them all.