ANODE CURRENT METER :

Power is measured by this meter. With the power turned to zero it will normally read about 20% full scale. It measures the current drawn by the oscillator tube in the generator.

The behaviour of the indicator on this instrument can tell a lot about the quality of the weld. Once a successful weld has been achieved the same reading can be expected each cycle.

A good weld will cause the indicator to rise, dwell then fall slightly. After it has fallen, the weld timer should be set to stop the cycle.

Should the die sit on the cardboard inserts a lower reading will be observed. When the indicator goes hard over to full scale, an overload has occurred and the machine will switch off.

If everything can been seen to be normal yet the reading is 40% low a supply phase fuse could been blown. No reading indicates no HF power at the valve.

GRID CURRENT METER :

On large machines this meter is fitted to indicate the grid current flowing in the oscillator circuit. It is for the tube condition diagnosis and is of little interest to the operator.