Space Control lives again
03-27-2008, 09:47 AM
#1
Thread Starter
Space Control lives again
I have managed to get another Space Control working, this one has issues with the elevator and rudder not moving enough. Along with the usual re-cap that all old electronics need , there were some bad transistors and resistors that needed replacement.
I had a bit of bad luck in testing it when the power pack in the transmitter went up in smoke and caught fire! Turning the switch off did not stop it, and so I quickly unplugged the power pack but that had no effect, it was still shorting and burning. As a last ditch effort, I opened the lid and saw glowing wires, so I grabbed the dykes and cut the wires, that stopped it.
What happened was the power pack has a DC to DC converter that makes 135 volts from a 7.2 volt 9000mAh battery pack. It also supplies 2.4 volts from the same pack. These voltages are for the tube plates and fillaments respectively. The transformer is wound with fine enameled solid copper magnet wire, and over time the enamel broke down, and the windings shorted. This made the converter transistors draw more amperage, and although the converter was working, it ran pretty hot. Eventually, one of the transistors shorted and caused the transformer windings to glow like a toaster and set fire to the power pack's plastic case, it was spectacular, too bad nobody was with me to capture it on camera.
After a one month setback to rebuild and rewire the converter, I fired it up and was able to finish repairing the receiver brick, which now is working correctly.
I had a bit of bad luck in testing it when the power pack in the transmitter went up in smoke and caught fire! Turning the switch off did not stop it, and so I quickly unplugged the power pack but that had no effect, it was still shorting and burning. As a last ditch effort, I opened the lid and saw glowing wires, so I grabbed the dykes and cut the wires, that stopped it.
What happened was the power pack has a DC to DC converter that makes 135 volts from a 7.2 volt 9000mAh battery pack. It also supplies 2.4 volts from the same pack. These voltages are for the tube plates and fillaments respectively. The transformer is wound with fine enameled solid copper magnet wire, and over time the enamel broke down, and the windings shorted. This made the converter transistors draw more amperage, and although the converter was working, it ran pretty hot. Eventually, one of the transistors shorted and caused the transformer windings to glow like a toaster and set fire to the power pack's plastic case, it was spectacular, too bad nobody was with me to capture it on camera.
After a one month setback to rebuild and rewire the converter, I fired it up and was able to finish repairing the receiver brick, which now is working correctly.
