I finished the changing of all the wax paper capacitors this morning, there were only 6 in total, even the 100pF and 200pF were wax paper and copper rolled into a cylinder, and showed a small leakage. It is surprising how much the wax sizzles when you heat it with a soldering iron, it must have absorbed quite a lot of water over the years.
This is the underside of the chassis now all the components have been checked and changed.
I seem to have got a bit low on yellow axial capacitors, they are the best type for re-stuffing, making it very easy once you have extracted the old wax mess. I open up the rolled over end of the capacitor by running a screwdriver around the rim then a soldering iron bit. Then pull the end of the capacitor out they normally break away easily, once the capacitor has been warmed and the wax softened enough the rest of the capacitor can be pushed out from the other end. I sometimes keep and reuse the end connections to the capacitor to act as stoppers on the new capacitors leads to support the end plugs.
I was puzzled by a contact designed to make with the tip of the tuning knob spindle. It had come loose from its mounting, the wire from it goes to the dial lamp. Its purpose was clear when I looked for the dial lamp on the schematic. The tuning knob spindle is on a spring and it can push in and makes contact to switch on the dial lamp, but normally it is disconnected to save battery.
2 of the resistors were way of their tolerance. One listed as 50k was reading almost 100k so I tacked another 100k to it and hid the small additional resistor under the original dogbone. Another 250k resistor was reading in excess of 700k, I managed to find another small dogbone type which measured about 300k and fitted that.
The reaction condenser is rather unusual, it is mounted on the back and ganged to a 10k potentiometer which also acts as the volume control. The pot shows no continuity so it is going to have to come out to be dismantled to see what is going on. Unfortunately I will also have to remove the wave change switch in order to be able to remove the reaction control.
I may be a little while.
Mike
This is the underside of the chassis now all the components have been checked and changed.
I seem to have got a bit low on yellow axial capacitors, they are the best type for re-stuffing, making it very easy once you have extracted the old wax mess. I open up the rolled over end of the capacitor by running a screwdriver around the rim then a soldering iron bit. Then pull the end of the capacitor out they normally break away easily, once the capacitor has been warmed and the wax softened enough the rest of the capacitor can be pushed out from the other end. I sometimes keep and reuse the end connections to the capacitor to act as stoppers on the new capacitors leads to support the end plugs.
I was puzzled by a contact designed to make with the tip of the tuning knob spindle. It had come loose from its mounting, the wire from it goes to the dial lamp. Its purpose was clear when I looked for the dial lamp on the schematic. The tuning knob spindle is on a spring and it can push in and makes contact to switch on the dial lamp, but normally it is disconnected to save battery.
2 of the resistors were way of their tolerance. One listed as 50k was reading almost 100k so I tacked another 100k to it and hid the small additional resistor under the original dogbone. Another 250k resistor was reading in excess of 700k, I managed to find another small dogbone type which measured about 300k and fitted that.
The reaction condenser is rather unusual, it is mounted on the back and ganged to a 10k potentiometer which also acts as the volume control. The pot shows no continuity so it is going to have to come out to be dismantled to see what is going on. Unfortunately I will also have to remove the wave change switch in order to be able to remove the reaction control.
I may be a little while.
Mike
