Repairing amplifier method: (here refers to the method of general overhaul of the power amplifier) 1, the voltage amplifier section power supply (such as: voltage amplifier section is of positive and negative voltage of 45V, use positive and negative voltage of 20V to repair it), it's safer that way. 2, repair amp circuit, be sure to input amp signal short circuit to ground. 3, the amplifier power tube removal is impossible for me to fix it. Power tube removed, not midpoint voltage measuring. Midpoint voltage either positive pressure or negative pressure. And is either positive or negative values of the power supply voltage. Speaker protection circuit relay without suction. Note: step-down repair may make the circuit of the relay not absorbs, this is normal. Don't doubt protected neutral-point voltage is too high.SkFservice manual download site
SkFservice manual download site
4, if one is afraid to burn power tubes, you can do so: for the time being used for pipe 2SA940, 2SC2073 alternative. Because the average household power amplifier not a partial class. Quiescent current is small, not burnt tubes, pipes must be with the heat sink paste. Don't make too much noise when the audition, then trumpet auditions. 5, on the bias circuit component parameters must be accurate. Biasing transistor pin, tube-type must be selected. 6, use the pipe "complementary pair tubes" amplified double beta number should be consistent. 7, various supply voltage is a negative value must be symmetrical. Front electric 12V positive and negative or positive and negative 15V to symmetry. Especially inexpensive amplifiers, pre-supply voltage from power supply, and then by the resistance after buck for preamp supplies. A long time, current limiting resistance will become larger, positive voltage current limiting resistor rather than a negative voltage current limiting resistor bad fast. Because a single amplifier, voltage circuit than the negative-voltage circuits. In other words, positive voltage load is larger than the negative voltage of the load! So, predecessor of positive and negative voltage asymmetry will directly affect the output voltage asymmetry. 8, circuit after the confirmation, you can access power transistor test machine. Restore the original input signal short contacts. Voltage is recovered, it is best to use a voltage regulator, slowly, from low to high pressure. Connect speakers to have any harmful voice, as long as the circuit no faults should be no sounds.

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