Wiring a Technics SP-15 turntable for remote start?

[spinjector]

Can anyone pass along any helpful hints on wiring an old Technics SP-15 turntable to a broadcast console for remote start?

I wired an SP-15 into my college radio station's console...ummm...15 years ago, but I can't remember exactly how I did it.

I cannot remember if the console output a momentary closure that paralleled the Start/Stop button, or - and this is the direction my memory is leaning - the console provided a continuous relay closure to make or break the power going to the drive coil.

Now that I am older and wiser (mostly), triggering the Start/Stop button makes more sense, and I can't think of how or why the previous student engineer(s) did it by breaking the coil power.

Thanks guys.

 

[MattB]

> Can anyone pass along any helpful hints on wiring an old
> Technics SP-15 turntable to a broadcast console for remote
> start?
>
> I wired an SP-15 into my college radio station's
> console...ummm...15 years ago, but I can't remember exactly
> how I did it.
>
> I cannot remember if the console output a momentary closure
> that paralleled the Start/Stop button, or - and this is the
> direction my memory is leaning - the console provided a
> continuous relay closure to make or break the power going to
> the drive coil.
>
> Now that I am older and wiser (mostly), triggering the
> Start/Stop button makes more sense, and I can't think of how
> or why the previous student engineer(s) did it by breaking
> the coil power.
>
> Thanks guys.
>
Trigger the start and stop. No reason to mess with the drive coil.
<P ID="signature">______________

njrm.org - The New Jersey Radio Museum
</P>

 

[awsherrill]

I seem to recall the SP-15 brought out the start-stop switch contacts to a jack underneath the drive deck. Or maybe that was a user modification.

One tricky thing about remote start-stop of these TTs...it was a toggle deal. There was a start-stop switch with a single pair of contacts. Short the contacts and the turntable started spinning, short'em again and it stopped. It got confusing if your console buttons got out of sequence with the TT operation, i.e. you hit the ON button on the console and stopped an already-spinning turntable. I think Henry Engineering sold a logic box that would interface between the console and turntable to keep the ON and OFF logic correct.

 

[SML]

> Can anyone pass along any helpful hints on wiring an old
> Technics SP-15 turntable to a broadcast console for remote
> start?

Open up the bottom, find the yellow and orange wires in the bundle coming across from the switch, strip away a little insulation from each wire and solder on a pair to the outside or an insulated jack on the bottom. A momentary closure starts, another stops it.

 

[spinjector]

Thanks. That's probably what I will do, but I would rather put a small relay right there that I can fire with a 5v pulse from the board. I'd worry about that control line picking up noise inductively from the environment.

Thanks for the suggestion!

> Open up the bottom, find the yellow and orange wires in the
> bundle coming across from the switch, strip away a little
> insulation from each wire and solder on a pair to the
> outside or an insulated jack on the bottom. A momentary
> closure starts, another stops it.

 

[spinjector]

Yes that is the case. I will just wire it to the ON button and let the board-ops keep track of whether or not the deck is spinning, they shouldbe able to handle it. Hmmmmm, then again some of our board-ops might have trouble with that.......

> I seem to recall the SP-15 brought out the start-stop switch
> contacts to a jack underneath the drive deck. Or maybe that
> was a user modification.
>
> One tricky thing about remote start-stop of these TTs...it
> was a toggle deal. There was a start-stop switch with a
> single pair of contacts. Short the contacts and the
> turntable started spinning, short'em again and it stopped.
> It got confusing if your console buttons got out of sequence
> with the TT operation, i.e. you hit the ON button on the
> console and stopped an already-spinning turntable. I think
> Henry Engineering sold a logic box that would interface
> between the console and turntable to keep the ON and OFF
> logic correct.

 

[rrsounds]

The problem with the SP-15 MKII (an otherwise wonderful, quick-start direct drive turntable, built like a tank) is that a single button toggles between the start/stop functions. If it's off, the button starts it. If it's running, the same button stops it.

Just remoting the button's function means you don't have a dedicated button for each purpose, and if you hit the button twice accidentally, you get a 'burp' of audio, as the turntable starts and immediately stops again. Not very professional sounding on the radio!

One way to solve this is to power a small relay in parallel with the SP-15's brake. The brake is engaged when the turntable is stopped, and off when it is running. By routing your (two) remote start and stop buttons through the NC and NO contacts of the relay to that single toggle control of the turntable, your remote buttons will ALWAYS be in sync with reality. It is IMPOSSIBLE to 'stop' the turntable with your remote 'start' button, and vice versa. Voila!

You can also use additional contacts on the relay to send voltage to lamps in illuminated pusbuttons, for visual feedback indication to the operator as to whether the turntable is running or not.

BTW, I didn't come up with this; Greg Strickland showed me, MANY (~30) years ago!

David Reaves
TransLanTech Sound, LLC
Home of the Award-winning "Ariane Sequel" Digital Audio Leveler



> Yes that is the case. I will just wire it to the ON button
> and let the board-ops keep track of whether or not the deck
> is spinning, they shouldbe able to handle it. Hmmmmm, then
> again some of our board-ops might have trouble with
> that.......
>
> > I seem to recall the SP-15 brought out the start-stop
> switch
> > contacts to a jack underneath the drive deck. Or maybe
> that
> > was a user modification.
> >
> > One tricky thing about remote start-stop of these TTs...it
>
> > was a toggle deal. There was a start-stop switch with a
> > single pair of contacts. Short the contacts and the
> > turntable started spinning, short'em again and it stopped.
>
> > It got confusing if your console buttons got out of
> sequence
> > with the TT operation, i.e. you hit the ON button on the
> > console and stopped an already-spinning turntable. I
> think
> > Henry Engineering sold a logic box that would interface
> > between the console and turntable to keep the ON and OFF
> > logic correct.
>

 

[spinjector]

Thanks for the idea about the brake solenoid. But what I ended up doing was sticking a little 5v relay inside, with the N.O. contacts in parallel with the Start/Stop button. This is how it was done (I think) at my college radio station, and the daytime personality who will be using the TT went to the same school as me, and so she is used to both the turntable, and the Start/Stop nature of the remote start...

I used a relay because I did not want to cross the electronics of the TT with the open-collector electronics of the console, which in turn would link it with our house 5v supply, and thus the other 11 consoles in the building. Not a good idea for sensitive TT electronics I think...

Thanks!