Oracle Delphi MK III speed issues...FIXED!! YEAH!
Just bought an Oracle Delphi MK III and love it (had one long time ago) and decided to get another.
Anyway, played maybe an hour since last night and out of the blue, it just started speeding up all by itself, sort of around 38-39 RPM. I would tweak the pot, get it synch'd again then it would run fine for about 5 minutes, then start speeding up. Tweak again, then it would slow down... ARG!!:smash:
Put a little Cramolin on the pots and gave em a wiggle. Worked for a few minutes then :bawling: :hot:
Anyone run into this with a MK III?
PS I took the speed control board out....filled with epoxy. Bloody hell. :smash:
PSPS Has a new belt also and everything on the plater is clean and fresh oil installed.
kilohertz...seems Oracle Owners need to stick together...
Double check the voltage output from the power supply. If it is rock solid, then try adjusting it to another (arbitrary ) speed and leave. Check it again.
2 things could be going on:
The motor is shot, and therefore tries to pull more current (and thus voltage) than the power supply can provide, or the motor is fine and the PS is shot.
Do you have the "Turbo" power supply or the "regular" one?
Let me know how it turns out. You may also want to contact
THE Oracle Turntable Guru.
Thanks for the reply. I don't know how to tell if it is a turbo or not. What should I look for?
After spending some time at the local hifi shop yesterday, finding a problem with a very high end Nottingham turntable and fixing it, I realized that maybe all this needs is some lube on the bearings, as it is now 20 years old. I dropped a little 10 weight synthetic lube on the bushings and shazam...it's been working all night and still is going this morning. Guess it was the motor. :smash:
Thanks for your help and yes, us Oracle owners need to help each other out.
Oracle speed problem
I have spoken a number of times to Pierre at Oracle Audio, about the speed issue.
He mentionned the that the bearing needed to be properly oiled & to experiment with different oils.
I am now using a mix of fine oil used for in line skates ABEC bearings + some slippery additive sold in Canada & called Jig-A-Loo - the resulyt was added speed. (see photo)
I also sent the platter & bearing some time ago to Oracle for ajustement - that did help.
Also, Oracle has new bearing trust plates - mine was cracked...
As for the speed variation, I can write a few chapters about my motor problems as Oracle has no old parts and can offer only the new $1500. motor unit.
I am using the Origin Live turntable motor system, namely 2 DC200 motors, the ultra motor control and the upgraded power supply.
I also get sometimes (not often) a speed increase for 1 to 2 minutes & then it settles down. But I suspect the 25 speed pot is the culprit.
I also connected the motor control to a PS Audio current purifier - the speed was much much more stable with that connection.
Also, I replaced the 18 gauge power supply cord with a 10 gauge
home made power cord & that also made the speed more stable.
Citation16 and kilohertz
It seems that you both have found great solutions and references. I assumed that the bearing and motor were in good shape, and replied based on that.
Yes, the motors are all getting to be 20+ years so any solutions and ideas are good ones. Good power supplies (and/or good AC regeneration units) , and good bearing and lube are essential.
the link I made to the Oracle Guru, as bold'd in my last post, was Brooks Berdan. He did become fairly famous doing after-market work on Oracles. A good resource for (perhaps) used items and possible upgrades as well.
If I end up with a bearing problem, I think I'll get a custom one made to fit the Oracle, but use a Teflon wear plate, and a ceramic ball, if possible. There are good industrial motor rebuilders that can custom wind and finish an existing motor to new specifications if one cannot afford the DC motor upgrades.
do you know any good place that can completely rebuild my oracle motor? The new base and motor is 2,600.00 Way out of my range. thankyou for any help you can give. Keith
Brooks Berdan may know. Do a web search, he still has a shop and was THE go to guy for Oracles in the past.
As far as I know all the early Oracle tables use a "flat" style motor. Sourcing motors is a real PITA. A couple things come to mind though. If you can measure the speed of the motor, great. If not, do a very accurate measurement of the diameter of the drive pulley, and the driven pulley (where the belt rides on the platter). Divide the driven by the drive pulley. The result is how many times faster the drive motor must spin in comparison to the platter.
diameter of the platter =300mm
diameter of the drive pulley =17mm
then (300/17)*(100/3)rpm = 588.23 rpm for the drive motor.
Once you understand this, you can find whatever motor you can and fit it to you turntable.
There are a number of motors out there, the easiest to implement is a AC Synchronous motor. You may not have much control over the mains frequency, but you can have (at least) a turntable that works. If you want more accurate speed capabilities, you can get hold of some sort of power regeneration device that can do one input ,and lock the speed down by altering the frequency of the power station, until your speed is rock solid. There are other schemes like building an AC speed drive (or purchasing one). You also buy a robust DC motor and speed controller (or make one) and drive the platter with that.
If your table is a Delphi or Premier, changing motors may be a lot easier than on my old Alexandria. I may have to "skeletonize" my old table.
I know I'm posting in and old thread.
My Mark III just began to give me what I would call extreme wow and flutter. Everything had a warble to it which made it just unlistenable.
History: Last year, when I first got the table I thoroughly cleaned it including the well, spindle and bearing. The thrust plate and spindle and bearing were coated with a varnish where the oil had evaporated and dried up. I filled the well with 3 cc of old oil I had from an Acoustic Research XB table (which was a brownish colour) and bought a new belt. (19.7 although I think perhaps it should be a 20.0) Set the suspension height to 21mm and the top of the brass pulley to 71 mm per advice from Jacques at Oracle.
Everything worked fine for a few months then ugh.
After much reading I solved the problem by doing 5 things.
1. Removed and cleaned the brass pulley. It had gummy varnish in the bottom.
2. Put 2 drops of SAE 20 electric motor oil on the shaft of the of the electric drive motor.
3. Replaced the pulley making sure the top of it was 71 mm above the acrylic base per Oracle spec. I had to pull the shaft up and mount the pulley as high as possible to achieve this, as the shaft had somehow settled down into the motor about 1/8 - 1/4 inch. I didn't really take note exactly how far.
4. Replaced the oil in the well with fresh SAE 20 electric motor oil.
5. After letting the platter settle for about 20 min.; Adjusted the suspension height down from 21mm to 18mm so that the bottom flange of the pulley was in line with the bottom of the platter hub. This allowed the belt to run parallel to the bottom of the platter instead of the slight angle it had previously when the pulley was lower than the bottom edge of the platter.
Result: Sonic Bliss.
One thing that Brooks does on the bearing is to run the table for 24 hours or more straight and then clean the shaft and bearing hole out completely and reoil. If the tolerance is extremely tight I wouldn,t use a straight 20 wt oil. Very tight tolerances require thinner oil .
I use Mobil 1 synthetic or Tuffoil personally but if it works out for you then you have found the right combination of tolerance and viscosity
If the shaft has any visible wear rings that you can feel or measure, then you need a new shaft and bearing that no kind of oil will cure
bearings and things...and motors
The original motor on my Alex Mk II is still intact, but one needs to be prepared for the day that it is no longer working as apparently none are available. Thankfully I do have adjustments available to set the speed. How did I do this?
My stock Alex has speed adjustments available via a variable resistor/capacitor circuit that are accessable externally. These are the "fine" adjustments. Within the plinth mounted on the circuit board are two small adjustment pots. These are not accessable externall. I took a Dremel and cut out a rectangular opening to allow for external access. I then made a small plug from some thin, dense "craft" foam to put into the hole. You can't see the plug easily, but dust is kept out of the interior of the plinth where the electronics.
If I can find a photo I'll post it, otherwize I'll take a photo and then post it.
|All times are GMT. The time now is 11:47 AM.|
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.
Copyright ©1999-2016 diyAudio