How it works: One video

OK, I recorded a video just to show how the whole thing works. The Sinfonola is open, without the front speakers, so the inners can be seen. (p.d. those in the TMP will recognize the song being played)

BUILDING THE STEPPER (...and III)

Ok, it is finished now.
I used a multi-purpose PBC because being a prototype I had to make some changes on the fly. Now that the design is clear to me, if I have  to make another I will use a blank PBC. I also used the Conrad processor, because I didn´t have time to program a PIC in assembler. Again, if I do another stepper in the future, I rather use a PIC.
Anyhow, all is enclosed in a black box, so from outside, nobody would be able to tell...

On the left is the processor with the power supply and a couple of ICs to drive the the transistors and micro-relays that will make the selection. The relays are in the top and right. I will upload an schematic as soon as I draw it, but is very simple: the real engine is the processor.

The box is lying in the bottom of the machine and uses the connectors to the wobble plate (same than the original rock-ola stepper).

Of course it didn`t work the first time right, but after a couple of chanes in the hardware and correcting a few more bugs in software, now is running flawless.  I made some stress tests today: I ran 50 selections without a single flaw.

I will record one video and will upload it next week.

BUILDING THE STEPPER (II)

I started building the stepper. Last day I tried a 68705 unit that I had at hand to verify that the connection would work. I was too busy to buy a PIC and refresh my assembler knowledge, so I continue using the 68705 programmed in BASIC. Here is the unit,  understanding perfectly the pulses from the wallbox. It is connected trough an optocoupler. I will upload schematics of all later.

This is the stepper box. I just fixed the connectors, three as I planned. The box, from outside, it actually resembles a real stepper, somehow smaller. 

 The small connector in the front is the three-wire to the wallbox, the two Jones plugs on the right are the ones that connect to the selector (one of these connectors laying around in the floor of the cabinet). There we have contacts for all the letters (10), numbers (5) the even and odd tracks (2): a total of 17. The small connector in the left has to go to the Central Unit, to get power supply (32 DC and 25 AC), the other end of letters, numbers and tracks and last, the  switches under the keyboard that tell the Sinfonola that a selection has been made.

I had to install a new connector in the central unit. This is the only modification I had to make to the Sinfonola, and is not serious: I goes almost unnoticied, does not interfere with the normal function at all and if I remove the stepper in the future, it will not affect at all the machine. I used for this an existing hole, and I ran the cables to the floor of the jukebox.

If I don’t have any unexpected problem, all should be working during next weekend.

BUILDING THE STEPPER (I)

As I commented the other day, the device that receives the pulses from a wallbox and commands the Jukebox is called “stepper”. The steppers were sold as an option, and were connected to the jukebox inside the own jukebox.

The Sinfonola never had this option available. At the very beginning, I tough buying a Rockola stepper like the one above and adapting it to the Sinfonola 2000, however this has many problems like:

-          Rockola and Sinfonola have, for some reason a reverse disposition of numbers and letters in the selector.

-          The Sinfonola has a connection for the contacts in the selector, but it hasn’t the other connector for the control unit

-          I will run the wallbox and the stepper at 50Hz instead the American 60 Hz.

My second option was to build the stepper from scratch using pinball stepper relays (the gottlieb AS relays or the lottery relays). I tried a couple of these (thanks to Jetlagger for lending me these), but they are big, noisy and not very reliable. The third option was to use relays or transistors commanded by a combinational circuit. The change from numbers to letters would be made with a capacitor that cannot discharge trough the train of pulses, but has enough time to get discharged in the gap from numbers to letters. This is the way it was done in the original steppers. However this requires designing an R-C network with no much tolerance. After a couple of tries, I decided to change to a PIC microprocessor that will decode the pulses, translate the selection to a Sinfonola language, and activate the output in the selector.

Finally I will use a PIC16F73, even is many years now that I don’t program in assembler. I also don’t feel very happy using a microprocessor in a 70´s machine, but I will enclose it in a box with an external appearance of an older stepper. I already got a couple of the Rock-Ola/Sinfonola type connectors, called Jones Connectors (Thanks again to Miguel Jetlagger) and I will make it to look like the picture below, with the connectors for the selector (18 pins), one of three pins to the wallbox, and I will need 9 signals from the Control Center.

During the weekend I made some tests with an older 68705 application board (that I can program in BASIC much easier) and in 5 minutes I had decoded the pulses and also figured out how to connect it to the Sinfonola. Now I am sure I will be able to connect wallbox and Jukebox. I will post some photos tomorrow.  

HOW DOES THE 3W1 WALLBOX WORK?

ok, to get both machines connected I had first to understand how the wallbox works. As I said before, the 3W1 handles the communication with the Jukebox trough 3 wires. Two are for power supply and they can be connected to the 24 AC from the Sinfonola, the other is the clever guy, the one sending the selection keyed in the wallbox, that has been previously encoded in pulses.

 WALBOX PULSING

Everywhere in the manuals (and I will do the same), it is said that the walbox is “sending pulses” to the stepper unit to indicate the selected combination of a number + letter.

We say “sending pulses”, because is a more graphical figure, but it is not true: The poor walbox does not send anything, simply switches to ground or not the wire for signaling.

Once said this is very important that if we do any design using the signaling circuit, we do not pass current trough it. Originally the signaling was connected in the Jukebox to a vacuum tube that draws no current from the circuit. If instead we install a relay that will take some milliamperes, we will have sparks that will wear out the contacts in the wallbox. If you do your own design, try to use a transistor: in our case we will use an optocupler to isolate the voltages in the wallbox to the rest of the circuit.

HOW THE PULSES WORK:

The wallbox has a disk with a central blade that when rotating wipes trough 26 contacts. Depending on how the selection keys ground these contacts, we will have a different number of pulses:

- The wallbox first sends a train of pulses, one per number selected (i.e. if the selection is A-8 it will send 8 pulses).

- Immediately after it will send 11 pulses if the selected letter was even (B, D, F, H, K) or one single pulse with a width of 11 if it was and odd letter (A, C, E, G, J).

- After this will send nothing for 2 pulses width time.

- It will then send 1 pulse if the letter was A or B, 2 for C or D, 3 for E or F, 4 for G or H and 5 if it was J or K.

SOME EXAMPLES

Just to be able to visualize this, which is no easy, I made the followin drawing:

The first train of pulses is the most complex one: 10 – K, so has 10 pulses for the number, 11 pulses for the even letter, a pause of two and 5 pulses for the K.

Next is the easiest: 1 – A which is 1 pulse, the large pulse for odd letter and 1 for A. Only three pulses in total, this is the shortest possible.  The next is 1 – B, the difference here is 11 more pulses for the even letter.

Try to figure out the last one!

In the next entry (now that is clear to me how the wallbox operates) I will go for the Sinfonola200, which is a bit more complex.

Connecting a 3W1 Wallbox to a Sinfonola2000

Hi,

I just got a 3w1 Seeburg Wallbox, and I intend to connect it to my Sinfonola 2000 Jukebox. This blog can be useful for someone with the same idea.

THE JUKEBOX

The Sinfonola 2000 is a copy of a Rock-ola 443 (100 selections mechanism) made in Spain by Gedasa. I believe that Rock-ola licensed to this Spanish manufacturer the patents for his mechanism and Gedasa produced their own Rock-ola under the name of GEDASA. If someone has more information about the history I would appreciate knowing.

There are minor differences between the Rock-Ola and the Sinfonola: The amplifier is completely different and the keyboard is also connected differently, but most of the parts are interchangeable (I replaced some parts of the turntable, the gripper motor, and the coils that make the selection in the wobble plate with original Rock-ola, and all fit like a glove). Also the external layout of the machine is slightly different. Being the shape of the machine the same, the title cards are located over the front speakers in the Gedasa and the selection keys are higher.

The Sinfonola2000 is ugly (sorry, but facts are facts. The Rock-ola 443 is also not a handsome machine. None of them are a match to a Tempo) and bulky. This is the reason I decided to hide it in a corner and put the wallbox in a more visible place.  

THE WALLBOX

The Seeburg 3w1 gets it’s name from the fact that only uses 3 wires to get connected to the Jukebox (one is ground, the others are mains at 24 alternate and signal). It has 100 selections and the shape that anyone would recognize as the right shape for a wallbox.

In the next days I will write more information on how the wallbox works and how I am progressing with the connection.