The Rosenfield AZ Coin-Operated Phonograph

[Shawn]

Scott,

A lot of the enjoyment I get from these coin-ops is seeing them operate. It is fantastic!!

So, the Rosenfield is scary, I admit that. Its a little dangerous, that is true, but it can be a great machine.  

Some of the danger from this machine comes from the electric motor.  Its 110 volt DC at 2 amps.  That can definitely kill. Most of the Rosenfields found today have either been converted from 110 DC, or came from the factory with a 110 volt AC motor.  Either way you have to be careful with line voltage in AC or DC. Lots of opinions on which is more dangerous. The bottom line is be super careful.
 
What I did to limit the danger is to have a 110 volt DC isolation transformer built for mine.  With this type of transformer, even if you accidentally touch a hot wire, you won't be the ground if you are connected to earth ground.   I also have a strict protocol for the machine when it is plugged in.  The doors and lid are locked with no entry.  And I only plug it in to play it, then unplug it.  If there is ever a problem during the play of the machine, the first thing I do is to unplug it before opening the lid or the doors. I also count to 20 as there is still residual charge in the capacitors of the isolation transformer.

Note here - you may realize that I broke this protocol to film "How Does That Coin-Operated Phonograph Work" for the Rosenfield AZ. That is true. It is one of the few times it has happened. I was super careful, and it really was the only way to produce a quality product. The good news for me is, I survived!

The mechanical action of the motor is also scary and can cause damage. It is a powerful motor. The big issue is that the motor binds up and either breaks something, or burns up the motor. Either is a bad outcome! You can end up with broken parts, stripped gears, or a useless motor. Here's what you need to watch out for. 

- The spring is wound too tight, and when the motor engages to wind the spring at the end of play it binds
- The gearing in the transfer box (the rounded black and gold stenciled part with the Rosenfield tag on top) binds or is improperly oiled
- The carriage or Rosenfield feed-screw (in front of the AZ) or cam is not in alignment and binds during return, stripping or breaking gears
- Something else I have not experienced or thought of puts a part of the machine unexpectedly at odds with the force of the electric motor

Rosenfield created some safety measures to combat these issues in his machine.

First, the instructions clearly say that 2 amp fuses must be in place to operate the motor. This provides a level of safety to the motor when it binds up. As an electric motor spins, the energy from the electricity is 'conducted' to the rotor by the magnetic fields. However, when the motor is stopped, the energy becomes heat and burns up to motor, creating a short circuit. The fuses theoretically "blow" before that happens.

Second, there originally was a sacrificial linkage and pin between the motor and the transfer case. This linkage or the pin that secured it was intended to snap if there was some sort of binding or blockage, allowing the motor to spin freely and not cause physical or electrical damage. As one would expect over the years this linkage was many times (most times) removed, or replaced with material that does not snap, eliminating this fail safe.

The good news is that you can run the complete return sequence of the machine manually before you even plug it in! Its easy, here is what you need to do:

1. Remove that sacrificial linkage, or in AC driven Rosenfields disconnect the drive rod between the motor and the transfer case.
2. The transfer case drives not only the return mechanism up top, but also transfers power to, and drives the winding shaft on the AZ spring-motor. So disconnect the winding shaft linkage
3. Set your carriage at the end of the cylinder, in playing position.

You are now ready to operate the Rosenfield manually.

There is a large knurled knob protruding from the top of the transfer case (see picture).

This knob allows for adjustments when the transfer case is connected to the motor. Disconnected, it allows you to rotate the transfer case completely through a return cycle of the Rosenfield mechanism. Since the transfer case is also disconnected from the winding shaft of the AZ, it turns freely through the cycle without winding the motor.

I did this many times before hooking back up the linkages to ensure everything was oiled, and moving properly.

Additionally,
- You can make sure the AZ mechanism is wound only enough to play through one record. This will ensure it is not too tight when the motor engages at the end to rewind the AZ.
- Disconnected from the transfer case, you can bench test, and energize the motor to ensure it properly functions.

Once you've gotten confident with the mechanism working, you reset the carriage and mechanism back to the beginning, reconnect the AZ drive shaft and motor to the transfer case and drop a Penney!!

So hopefully I've given you some information that will build your confidence to get your machine going!! Its your decision, though. These are 100 year old machines and sometimes have a mind of their own!!

Shawn

[MTPhono]

Thank you Shawn - this is much appreciated!

Scott