Columbia 321 78rpm only turntable - UK Vintage Radio Repair and Restoration Discussion Forum

retroaudio · 29th Sep 2020, 8:33 pm

Hi,
This is a bakelite cabinet with a fairly common turntable with a hysteresis motor. The speed and the smoothing is controlled by 2 large capacitors which seem to invariably fail and leak hot wax. I have worked on one of these before (The Marconiphone version) which was in an RG22A tabletop radiogram.

What is confusing me is the the Columbia version seems to be exactly the same but it also has a carbon resistor in parallel with a cap which is broken and I can't determine the value as the markings ar indistinct. The Marconiphone does not have this additional resistor and I am wondering what difference it makes to the circuit. The turntable in the Marconiphine is a 322 and in the columbia a 321

thanks Alex

29th Sep 2020, 8:33 pm	#1
retroaudio Pentode Join Date: Mar 2005 Location: Cairneyhill, Fife, UK. Posts: 135	Columbia 321 78rpm only turntable Hi, This is a bakelite cabinet with a fairly common turntable with a hysteresis motor. The speed and the smoothing is controlled by 2 large capacitors which seem to invariably fail and leak hot wax. I have worked on one of these before (The Marconiphone version) which was in an RG22A tabletop radiogram. What is confusing me is the the Columbia version seems to be exactly the same but it also has a carbon resistor in parallel with a cap which is broken and I can't determine the value as the markings ar indistinct. The Marconiphone does not have this additional resistor and I am wondering what difference it makes to the circuit. The turntable in the Marconiphine is a 322 and in the columbia a 321 thanks Alex