EMI TR3 recorder electic motor confusion. - UK Vintage Radio Repair and Restoration Discussion Forum

filmprojectors · 18th Dec 2017, 5:13 pm

The motor is from an EMI TR3 tape recorder. It's a GB Croydon 230 volt motor and I would like to use it as a take up motor on a film projector I am restoring, but I have 6 wires to connect? Black/white/red/blue/yellow/green it is a two speed motor 750 and 1500 rpm.

Has anyone got any ideas as to how to connect it to run at the 750 rpm speed? The original motor had only two wires.

Thanks.

Bookman · 18th Dec 2017, 7:47 pm

Here is a typical diagram for a two speed single phase motor. Not sure if it can be used to make some sense of the wires you have. In essence if all of the links are undertaken external to the motor then you ought to be able to determine the two windings in that the start winding may and probably will have a different resistance value.
The next problem will be establishing the start and end of all windings and ensuring correct interconnectivity of the low/high speed windings.
Good luck.

dseymo1 · 18th Dec 2017, 8:34 pm

The TR3 service sheet should give a good idea of how it should be connected, or if you have the rest of the machine, a simple bit of reverse-engineering is called for!

filmprojectors · 18th Dec 2017, 8:54 pm

I don't have the tape recorder just the motor, it was given to me by a friend.

Station X · 18th Dec 2017, 8:57 pm

I'd start by using a meter on ohms range to determine what the internal wiring is like. You should be able to identify at least two separate windings.

filmprojectors · 18th Dec 2017, 10:08 pm

Yes I have done that and there are three windings with 185 ohms resistance on each.

Boater Sam · 19th Dec 2017, 4:33 am

Have you identified the common negative? The 2 run windings are in series, 370 ohms across the 2. Across the start winding and the 2 run windings all in series you will have 555 ohms.
You will also need to find out the suitable value of start capacitor.

If you are happy you have the run windings identified, connect one up without the start winding. A twist should set it running without getting hot, you should be able to get both speeds to run by switching windings.

I would have expected the start winding to be slightly lower resistance than the runs.

Bookman · 19th Dec 2017, 2:38 pm

Just to add to Boater Sam comments give the shaft a twist.

barrymagrec · 26th Dec 2017, 1:40 pm

The is a Croydon JA34 1500 / 750 rpm sychronous motor, widely used on EMI and Leevers rich tape machines of the fifties and sixties as a capstan motor. It is wholly unsuitable for take up purposes as it has very little torque until it reaches synchronous speed.

It requires a 4uF start/run cap, mains rated.

For 750 rpm operation the connections are :-

red - live
yellow - neutral
white - cap

If you feed the cap from the neutral you should get clockwise rotation looked at from the top of the motor, feed from the live to reverse the rotation.

1500 rpm operation uses the green, blue and black wires but also connect the red, yellow and white wire together to produce the star connection.

18th Dec 2017, 5:13 pm	#1
filmprojectors Triode Join Date: May 2016 Location: Exeter, Devon, UK. Posts: 20	The motor is from an EMI TR3 tape recorder. It's a GB Croydon 230 volt motor and I would like to use it as a take up motor on a film projector I am restoring, but I have 6 wires to connect? Black/white/red/blue/yellow/green it is a two speed motor 750 and 1500 rpm. Has anyone got any ideas as to how to connect it to run at the 750 rpm speed? The original motor had only two wires. Thanks. Attached Thumbnails

18th Dec 2017, 7:47 pm	#2
Bookman Hexode Join Date: Aug 2017 Location: Taunton, Somerset, UK. Posts: 318	Re: EMI TR3 recorder electic motor confusion. Here is a typical diagram for a two speed single phase motor. Not sure if it can be used to make some sense of the wires you have. In essence if all of the links are undertaken external to the motor then you ought to be able to determine the two windings in that the start winding may and probably will have a different resistance value. The next problem will be establishing the start and end of all windings and ensuring correct interconnectivity of the low/high speed windings. Good luck. Attached Thumbnails

18th Dec 2017, 8:34 pm	#3
dseymo1 Retired Dormant Member Join Date: Dec 2007 Location: Shropshire, UK. Posts: 3,051	Re: EMI TR3 recorder electic motor confusion. The TR3 service sheet should give a good idea of how it should be connected, or if you have the rest of the machine, a simple bit of reverse-engineering is called for!

18th Dec 2017, 8:54 pm	#4
filmprojectors Triode Join Date: May 2016 Location: Exeter, Devon, UK. Posts: 20	Re: EMI TR3 recorder electic motor confusion. I don't have the tape recorder just the motor, it was given to me by a friend.

18th Dec 2017, 8:57 pm	#5
Station X Moderator Join Date: Jan 2003 Location: Ipswich, Suffolk, IP4, UK. Posts: 21,289	Re: EMI TR3 recorder electic motor confusion. I'd start by using a meter on ohms range to determine what the internal wiring is like. You should be able to identify at least two separate windings. __________________ Graham. Forum Moderator Reach for your meter before you reach for your soldering iron.

18th Dec 2017, 10:08 pm	#6
filmprojectors Triode Join Date: May 2016 Location: Exeter, Devon, UK. Posts: 20	Re: EMI TR3 recorder electic motor confusion. Yes I have done that and there are three windings with 185 ohms resistance on each.

19th Dec 2017, 4:33 am	#7
Boater Sam Banned Join Date: Dec 2013 Location: Middlewich, Cheshire, UK. & Winter in the Philippines. Posts: 3,897	Re: EMI TR3 recorder electic motor confusion. Have you identified the common negative? The 2 run windings are in series, 370 ohms across the 2. Across the start winding and the 2 run windings all in series you will have 555 ohms. You will also need to find out the suitable value of start capacitor. If you are happy you have the run windings identified, connect one up without the start winding. A twist should set it running without getting hot, you should be able to get both speeds to run by switching windings. I would have expected the start winding to be slightly lower resistance than the runs.

19th Dec 2017, 2:38 pm	#8
Bookman Hexode Join Date: Aug 2017 Location: Taunton, Somerset, UK. Posts: 318	Re: EMI TR3 recorder electic motor confusion. Just to add to Boater Sam comments give the shaft a twist.

26th Dec 2017, 1:40 pm	#9
barrymagrec Octode Join Date: Dec 2017 Location: Morden, Surrey, UK. Posts: 1,562	Re: EMI TR3 recorder electic motor confusion. The is a Croydon JA34 1500 / 750 rpm sychronous motor, widely used on EMI and Leevers rich tape machines of the fifties and sixties as a capstan motor. It is wholly unsuitable for take up purposes as it has very little torque until it reaches synchronous speed. It requires a 4uF start/run cap, mains rated. For 750 rpm operation the connections are :- red - live yellow - neutral white - cap If you feed the cap from the neutral you should get clockwise rotation looked at from the top of the motor, feed from the live to reverse the rotation. 1500 rpm operation uses the green, blue and black wires but also connect the red, yellow and white wire together to produce the star connection.