Panasonic MX - 4 movement of switch power supply, often easy to the fault of power tube and can't start the burning, and very stubborn. The machine power board and main board is separated, can separate out maintenance, circuit board is in standby state, after the power supply in the whole machine don't let the power plate when the phone is switched on in work condition should be in Q847 collector and Q846 base jumper between a 3.3 k Ω resistance. And the machine heart power board can't directly answer the false load, should be in power on the rear can pick off load, otherwise can't start. wH7service manual download site
 wH7service manual download site
 wH7service manual download site
 wH7service manual download site
After the machine to replace the power tube, is more than a month long, short, power tube and damaged a week, with the original power supply pipe. The root cause of the failure of power supply cooling plate is too small, easy to overheat and breakdown. wH7service manual download site
 wH7service manual download site
1. Increase the cooling plate. This method due to the internal space is limited, not easy to decorate, also not easy processing, and the effect not beautiful. wH7service manual download site
2. The use of micro air fan cooling. This effect is very good. TV set himself to adopt this method for the user to completely solve the problem. wH7service manual download site
Fan can be used within the computer heat dissipation axial flow fan are on sale (computer market). Just put the fan is fixed above the cooling plate. Power from the ignition coil, with around one or two rounds in core wires (depending on the motor speed of laps, as long as the heat dissipation plate is not too hot), after single-phase rectifier filter added to the motor. When the TV line circuit, during normal working voltage is induced fan didn't work; And when standby mode, fan does not turn. wH7service manual download site
 wH7service manual download site
3. Another method is to use two identical power tube parallel, single pipe can reduce half of the current, hot also reduce.wH7service manual download site