This 4 band French tube receiver manufactured in the late 1950’s came to the workbench completely dead. And since previous techs probably connected this receiver directly to the mains without taking the necessary precautions some considerable damage was done to the rectifier stage and killed the rectifier tube as well. So in this case checking the mains transformer for shorts was the first job on hand. Luckily the mains transformer survived the ordeal so we went ahead with further investigation, replacing the most damaged and relevant components to see if the receiver would come alive again …
After removing the chassis from the wooden case, the top side, apart from the collected dust, looks pretty good, but flipping it over to the component side revealed some serious issues …
Burned resistors, completely worn out electrolytic capacitors and very leaky oil filled capacitors in the rectifier stage.
Even these Allen-Bradley squared resistors were way of their value…
So after replacing the oil filled capacitors, electrolytic capacitors and bad resistors, as well as replacing the dead rectifier tube with a full bridge rectifier the receiver was prepared for the first test run.
After taking the necessary precautions, which is connecting the receiver to a variable AC power supply with current limiting protection, we gradually increased the voltage, and it came back to life again …
…even the magic eye tube survived …
No problem so far, all the voltages are within specification, no magic ‘white smoke’ appeared, no considerable hum in the speakers and after about 20 seconds … music. Although the recording is of poor quality, the warn and deep base sound of way back when really makes it worth the effort…
So, although the first test run of this tube receiver seems OK, many more bench time will be required in order to give this receiver many more years of lifetime and prevent an early return to the workbench. All electrolytic- paper- foil- and oil capacitors will have to be replaced, many resistors will have to be checked for their correct value, and some major realigning will have to be preformed in order to restore this old timer to the state as it rolled of the factory line.
