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In Reply to: RE: Servo Drive Basstech 7 questions posted by servojohn on November 12, 2007 at 18:27:51
Thanks for the post ServoJohn,
I've since tested the speaker using a car ampilfier, and sound does indeed come out of it :) I didn't crank it too loud b/c I didn't know if the amp had enough wattage, but it definately put out some serious bass.
The only problem is, it sounded kind of distorted. Almost like a flapping noise along with the bass? Also, as it's producing sound, you can hear squeaking near the rear of the box. Normal?
Your help is much appreciated, I can't wait to open this thing up to see what's inside :)
Follow Ups:
A "flapping" sound is likely a broken belt or cone. The squeaking or chirping noise at the rear of the cabinet could be a couple of things. First, the motor bearings may be dry or damaged, the armature of the motor is warped(this is a precision molded piece of magnet wire and epoxy, for very low moving mass)and squeaking as it rubs something inside the motor, or, more commonly in a properly working unit, just the brush noise as the motor changes direction with the input signal. Remember, technically this is a High Speed, Low Inertia DC servomotor, and has four brushes wired as two parallel pairs contacting the commutator.
Oh, there is one more thing that could be causing the noise at the back of the cabinet-there is a blower motor forcing outside air into the motor to cool it-driven from some of the input signal itself, so it is gauged to the amount of input power applied, and starts spinning slowly around 12-15volts rms input. The blower could have dry bushings and squeak. Lubricants can be used, but very conservatively in the main drive motor especially.
Best regards,
John
Thanks so much John,
One last question: What's the best way to open this thing up? I could probably guess at it, but asking you makes more sense :)
-Ryan
All the screws anchor into Tee-nuts on the cabinet.
You've got several 1/4-20 flat head allen bolts-eight on the very backside of the lid, along with four more on each side adjacent to the lid-there are wooden cleats just inside the lid to capture these side bolts. Undo the 16 screws, and remove the outer lid. There is a "Shark Fin" style brace attached to the outer lid permanently that fits into a groove on the inner lid. There are only four 1/4-20 bolts on the inner lid, remove these, and you will be looking at the drive module-lay this lid down like a drawbridge door, it will give you a spot to set the module on during reassembly. There is a 4 pin Molex type nylon connector in the bottom compartment of the exposed module, and the associated wires disappear through the PVC ventilation tube down into the input plate area. Disconnect this molex, then you will be able to slide the module out of the cabinet. The drive module has the servomotor, blower motor, belt arm/shaft assembly, and drive cones-the input circuitry is on the input plate, except for a thermal cut off device attached to the aluminum motor mount plate. It looks like a black plastic square, about .75"x.75"x.25" with a pair of .250" male quik connect tabs.
Best regards,
John
Thank you so much for all this detailed information. I'll be sure to let you know how the repairs go :)
-Ryan
How did it go?
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