First Dry Run - Ariston RD11 and Bi-Onda Controller

Since I am getting ready for my extended trip for work, I don't have a lot of time to devote to the Bio-Onda controller project.  Even worse is that I am having to pack everything away, which is making my wife very happy of course, but me sad.  Before I packed everything I did want to do a full dry run, that is to connect the controller to the Ariston RD-11 turntable and see everything turning in beautiful harmony as driven by the controller.

But before I could that, I did need to do a little bit of work on the Ariston's motor.  I heard a definite cyclic clicking noise coming from the motor and a bit more motor noise than would be considered normal.  Remember I had bought this turntable from a guy on a local internet classified, I have not done and servicing or reconditioning of the table yet. Suffice it to say for the moment that I did put some time into caring for the motor, after all it has a good 30 or more years of service under it's belt, definitely time for a little TLC!  I will not describe what I did with the motor in this posting, I will reserve that for another post later on.  I did get the motor working fine, much quieter.  So stay tuned for that info at a later date.

I did remount the motor and put the turntable together with the Bi-Onda controller driving the motor fully.  It worked great, sped the platter up no problem, spun nicely.  I tried out the 33.3 rpm and 45 rpm, the acceleration of the motor/platter looked good with the 'basic' values I had programmed before.  Speed was good.  I was especially curious to see how it ran at 45 rpm and was very happy with that.  I did notice that the speed, as per my default setting was a bit slow, but increasing the sine frequency by about 0.3 Hz brought it nicely up to 45 rpm, on the nose.  Me happy.  I did not spin any vinyl though, the table mounts an SME 3009 Improved and I have not set it up yet.  A full turntable reconditioning is slated for this unit, hope to make that into another series.

So far so good.  That was all the time I had for testing, I had to start putting all the equipment neatly and safely away until my return.  Geese, just when it was getting so close and running so well, now I will have to wait to finish it.  Sorry I could not include any pictures, was just too pressed for time.

SoundBound

Firmware Finito

(that means finished !)

Now that the hardware is behaving as it should, I decided to get back to the firmware and see about giving it some necessary cleanup.  There were features to add and unnecessary/debug code to clean out.

The main feature I needed to add, and the one that I was hesitant to tackle, was the acceleration feature.  I knew I needed to add an option to spin up the motor gradually rather than the full-on power up I have been using.  The main idea of course is to compensate for the inertia of the platter and belt system, the heavier the platter, the more important this feature is.  In fact, on my Ariston RD11 they designed the motor pulley with a slip clutch to deal with the inertia problem (you will find this on many Thorens turntables as well).

The way the acceleration needed to work is that when the user started up the turntable, the Bi-Onda controller would have to start spinning at a much lower frequency than 60Hz and slowly, or quickly, ramp up to the final frequency set by the user for their turntable.  I concentrated on acceleration and felt that deceleration was not as big an issue and decided to omit a deceleration routine.

My problem was trying to figure out how I would shoehorn this feature into the existing software without having to re-write the existing code or change the overall structure.  While writing a post on a blog for assistance, the ideas became clear to me and I was able to figure out a relatively simple way to implement it that would only require modification of one function subroutine and would work with any action that started up the turntable (calibration modes, 33 and 45 rpm etc.).  That also reminds me that another reason to implement acceleration is the feature that allows the controller to increase the motor speed to reach 45 RPM, this higher drive frequency can cause difficulty in these motors to start turning from 0 to the high frequency of the 45 RPM mode.  Accelerating from a lower speed usually works well in dealing with this issue.

I made the acceleration feature flexible to anyone's needs.  In calibration mode you are able to turn acceleration on or off and you can set your own parameters for: starting frequency, frequency step in Hz and the delay time between steps.  These are all stored in eeprom and only need to be set once.  So you can pretty much set up your own acceleration ramp (linear).

So now I will need to build an enclosure for this unit and put it in operation.

SoundBound