Manufacturer: Northern Electric, Toronto, Canada
Model: 5200
Approximate Date Of Manufacture: 1947-48
Type: 5-tube Superheterodyne AM BC band radio
Tube lineup: 35Z5GT, 50L6GT, 12SA7, 12SK7, 12SQ7
Status: working, restored
Where purchased: eBay, July 2005
The case is bakelite painted with a mottled metallic finish. This model as sold in six different colours referred to as Sea Grass Green, Alpine Rose, Desert Sand, Tusk Ivory, Delft Blue, and Tortoise Brown. I believe this was the Alpine Rose version. It looks copper coloured now but under the knobs where it hasn't been exposed to light for over fifty years, it is more of a red colour.
It is somewhat unusual having no back and the loop antenna on the side which looks like a spider's web. The chassis isn't directly connected to the line, but still could give one a nice shock if they were well grounded. Definitely not up to today's safety standards.
As received there were some small hairline cracks in the bakelite case and some small scratches in the paint, but overall quite attractive looking. It was not working. When powered up all tubes lit and there was some audio but no stations could be received. It was pretty clean inside, with just dust and no signs of ever being repaired except for a loose knob which had been taped. Even the pilot lamp was working. The schematic was found in the RCC manuals.
When testing the tubes the IF amp tube tested as possibly being shorted and the AF amp was weak. I substituted known good tubes and there was no change in symptoms. All power supply voltages appear nominal and the audio amp seemed to work okay (as checked by touching the volume control and getting a hum). I traced the continuity of all wiring, measured the resistors and coils. One oscillator coil was open. Fortunately I was able to reconnect the wire. After that the radio tuned in stations although it was a little distorted (a typical symptom of leaky caps and/or alignment).
All resistors were roughly within spec, although most were on the high side as is typical for carbon resistors as they get old. I replaced all of the paper caps. All were leaky except for the one to the phono input (because it has no DC voltage on it it is not as subject to the metal migration that causes it to become leaky). As is often the case, a leaky cap going to the volume control was the major culprit in causing distortion at higher volume settings.
I also replaced the electrolytic caps (four of them, three of which were in one can). I installed a small terminal strip and routed the wiring for the new electrolytic caps to the terminal strip, leaving the old cap intact but disconnected.
I performed an alignment as per the documentation. My recently acquired VTVM worked very well to peak the audio output.
I touched up some of the black paint on the two metal tubes as they were pretty scratched up. I cleaned the knobs and cabinet and reassembled it, taking a few last pictures.