Vibration table power amplifier board maintenance

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The power amplifier of the vibration table is a bridge amplifier output. Generally, the ten-ampere fuse of the tube is burned out, or the IRFP260N power amplifier tube is burned out.

The power amplifier board is usually measured with a multimeter when the power is turned off. The bad electronic components are replaced, and the voltage on the small resistor in series at the G pole of the tube can be measured after the power is turned on to check the quality of the tube.

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When measuring the power amplifier board, no 200V DC voltage is added. The voltage on the circuit board is 15V, which has good safety performance. At this time, it is okay to use an oscilloscope to view the square wave waveform.

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A small 5-ohm resistor is connected in series to the input end of the power amplifier tube. After the power amplifier output circuit is turned on, the DC voltage on the 5-ohm resistor is measured to know the driving current of the power amplifier tube. The normal voltage on the 5-ohm resistor is 0.6 to 0.88mV. If a voltage of 200mV is measured, the tube is broken and you need to replace the power amplifier tube and measure again.

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The power amplifier board is installed on the radiator during use, and then installed in the chassis. The space is small and it is not easy to apply voltage to the 5 ohm resistor. This can only be done after it is disassembled for maintenance.

zshasd1948

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