YAQIN MC-10T, Инструкция по эксплуатации, Страница: 6 / 13

INSTRUCTIONS
It’s very important to maintain the stability and accuracy of the operating points of the tube amplifier,
especially of the power amplifier tube. The screen current changes when the tube gets ageing, or
replacing the tube. Break away of the required operating points will influence sound resolution and
the stability of the machine. So, please check and adjust the screen current after a long time of use,
and it is the same when changing the tube.
METHODS of MEASUREMENT of the TUBE SCREEN CURRENT
Use a multi-meter to measure. Transfer the multi-meter to volts d.c.1V gear, and the minimum
volume of the amplifier, then insert the anode of the multi-meter pen into the positive hole ,
and the cathode into the negative hole respectively. The bias voltage should be about 0.35~0.4V.
Adjustment Methods of the Tube Screen Current
When replacing the tube, use a multi-meter to see whether there is a deviation from the screen
current. It should be about 0.35~0.4V when the standard supply voltage. If you find out a deviation,
please use tools to adjust the variable resistance in each hole . . The variable resistance
increases clockwise, and decreases anti-clockwise. Make sure that the screen current is about
0.35~0.4V with the standard supply voltage. Measure and adjust it once again when the tube is hot
enough.
Attention
：
When the machine voltage is in 220, 230V, 240V, please adjust and measure under the
standard power supply.
When the machine voltage is in 100V - 110V, 115V - 120V, please adjust and measure
under the standard power supply.
NOTICE
:
Sheath tube into the hole, should be careful in the direction of positioning
Pre delivery inspection and debugging of the screen current has been carried out by professional
staff, and we’ve scheduled numbers (eg.V1, V2, V3, V4) on the amplifier. So, please operate in strict
accordance with the numbers; otherwise, excessive current caused by screen current discrepancy
between the tubes will destroy the tube.