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Old 15th February 2008, 08:26 AM   #11
Nanook is offline Nanook  Canada
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Default a couple of ideas....

well the circuit must be accessible (seeing as you created anew plinth for it).

First step. Try a new voltage regulator, if handy with a soldering iron. 317s are cheap.

quickest simple, cheap "check, is to disconnect all the controls and the voltage to the motor. Use a fairly robust power supply (the Oracle one is something like 300 mA only) at 24 V--Princess Auto often has quite a few at very inexpensive prices. Try it, connected directly to your table (through a fuse if possible). There will be no speed adjustment available. With a potentiometer you should be able to get to speed correctly, as long as you are getting 24VDC or greater, and have a strobe disc, and/or test record. You could use an inexpensive DVM permanently attached to the circuit to allow you to make notes as to where the speed is stable at 33 1/3.

Or go get a high quality "lambda" or similar 20-30 VDC scientific grade power supply online or at a surplus, or something similar that will allow you to finely adjust the output DC

or build yourself a rock solid, absolutely stable 24VDC power supply.
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Old 15th February 2008, 01:10 PM   #12
g-horn is offline g-horn  Canada
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Thanks again Nanook
I'll let you know how i make out with this.
Mal
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Old 9th March 2008, 04:52 AM   #13
g-horn is offline g-horn  Canada
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Default Mark Kelly controller?

I'm not getting anywhere with my Oracle motor and controller. I can pick up a Maxon motor but I don't know how to get my hands on the controller. Does anyone have a Mark Kelly controller to sell? Either a kit or assembled. Any other advice would be appreciated. Cheers.
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Old 9th March 2008, 05:54 AM   #14
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Just a shot in the dark. The last Alex I saw had the same problem. There was a relay under the motor inside the housing. This relay switched when speed was switched. It was also very poorly soldered and a wire had broken off. Not all Alexandria's are wired this way though.
I have the mk III version schematic if that will help.
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Old 9th March 2008, 03:19 PM   #15
g-horn is offline g-horn  Canada
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Thanks for the suggestion Dan. How hard is it to get into the motor to check that connection? The bottom plate looks like it is pressed into the motor housing and there's no way to grab it. Any thoughts?

I would appreciate the wiring schematic if you don't mind.

Question: There is a fairly audible whirring sound coming from the motor when it is spinning. Is this motor shot?

Mal
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Old 9th March 2008, 04:07 PM   #16
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If you can't get the housing off, the relay is probably not there. The one I saw had three screws holding the case in place.
The sound you hear is probably the motor running too fast, but it is possible the thing is shot. The schematic shows electronic switching of the speed windings, so this may be fairly close to what you have.
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Old 27th March 2008, 07:52 PM   #17
240z4u is offline 240z4u  United States
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Interesting, I did the exact same thing that you have done. My speed is fine though. There are photos in this thread. http://www.audiokarma.org/forums/sho...oracle+kenwood

I have a dynamic stabilizer that was actually making speed vary all over the place. Its nothing but a box full of electrolytic caps. I would be happy to take a snapshot to show everyone if you want to build one.

My motor is silent when running.

I have to get off my butt and finish it. I have everything squeezed into a kenwood KD-2055 plinth. Looks decent, but I really need to finish it properly.

Are you sure you have the right power supply? A buddy of mine mentioned that there were actually several different output voltages on the oracles.

Evan

Who did your acrylic platter and how much was it? If you don't mind me asking!
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Old 27th March 2008, 08:50 PM   #18
g-horn is offline g-horn  Canada
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At this point I've pretty much given up hope for the Oracle motor/controller. I bought a Lab style variable voltage DC power supply and I have a Maxon 110191 motor on its way. I've also got a Teres controller on order. I think this should get me up and running.

As for the platter, I bought two pieces of 1.5 inch thick acrylic ($60) and laminated them together. I roughed out the circle on the bandsaw, then turned it on a big wood lathe (in my brother's custom cabinetmaking shop). The platter is surprisingly true! I took the platter and the plynth to a local machine shop to have the bearing set in.

I have one of those Kenwood rock tables downstairs too. Looks like you've done a great job with your upgrade!

Mal
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Old 27th March 2008, 09:27 PM   #19
240z4u is offline 240z4u  United States
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Thanks for the compliments. I had alot of restrictions in tools to make that table work (I live in an apartment and don't have decent tools here to do fab work).

Ill probabally stick with the oracle platter since its in good shape and has the clamp. Your using the oracle bearing right? I was going to have mine re-machined. The spindle does not fit all that well. It uses a thrust plate in the bottom, but was wondering if there was a way to incorporate a ceramic ball or something of the like. My thrust plate shows wear, and the platter does not spin as freely as I feel it should.

I have a buddy who may want to buy your extra oracle parts. Drop me an email if thats the case.

You have done a great job on your table, you should be proud!!


Evan
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Old 27th March 2008, 10:04 PM   #20
g-horn is offline g-horn  Canada
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Yes, I'm using the Oracle bearing - the sub-platter where the belt rides is under the new acrylic platter. I'm thinking that the new motor, pulley, belt will run on the platter itself, not the sub-platter. I may rethink the bearing at some point.
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