HD3070 with Automatic Gas Console Instruction Manual 5-73
16
MAINTENANCE
8. If chopper still does not output 280V after completing step 7, there may be a problem with the control signal or
the chopper module. The chopper drive signal comes from control board 1XPCB3 as an analog level from 0 to
+8 VDC, which varies the duty cycle and subsequent output current of the chopper. These analog signals are on
pins 5 & 6 of REC3 on control board 1XPCB3. See Figure 6-2 for location of 1XPCB3.
To determine if there is a problem with the chopper module or control board 1XPCB3, proceed as follows:
• Ensure that high frequency is still disabled (see step 1).
• Place voltmeter across output terminals of chopper (positive lead to (+) WORK and negative lead to
(-) TORCH and press the START command.
• If the voltmeter reads +280 VDC, then replace control board 1XPCB3.
• If the voltmeter reads 0 volts, then replace chopper module.
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