Super Class A power amplifier power circuit

The output protection circuit is composed of VT2i, VTn, etc. When the output tube is overloaded or short-circuited (　a", delete >2A
), the base current of the output tube is shunted to protect the output tube.
    Circuit adjustment: The first step is to adjust the Input stage and voltage amplification stage. Disconnect ‰, R31, remove and short-circuit AB.
Turn on the power supply. At this time, VDi~ⅥOu should glow. Measure the voltage of AB contact to ground and it should be ov (normal within ±1V) o Otherwise
, you can adjust the resistance or Rs. If the requirements still cannot be met, you can check VTi ~ VT12 one by one. If any abnormality is found, replace it.
    The second step is to adjust the downstream stage, remove the AB short circuit, connect ‰, R31 and R44, and connect RPi and Install and turn to the minimum position.
Insert a 5-8fl (5~10W) wire-wound resistor and an ammeter into each of the two ±30V power supply circuits, and connect the output end to
a thin dummy load. Turn on the power and turn the ) l and Wei Mao make the ammeter reading about 120mA. At this time, measure
the voltage between A and B. The normal value should be 4.1V. At the same time, V CE15=V(:E16 0. Measure the voltage between midpoint C and ground, and it should be within ± o,
within lv, and the tube has no heating phenomenon o
    Detect the dynamic bias circuit, input an AC signal at the input end, and measure the voltage at the AB terminal . If it can change between 4.1 and 5.5V with
the strength , it is normal. o Everything is normal After adjustment, let it sit for 30 minutes and then measure again. If
there are no abnormal changes, the adjustment work is over.
    ‰ and ‰ are the negative feedback loop of the whole machine, and the closed-loop gain of the whole machine is A v - R4/R45≈29dB.