Troubleshooting & repair, Meter circuit accuracy test – Lincoln Electric NA-5S User Manual
Page 119
F-66
TROUBLESHOOTING & REPAIR
F-66
6. Test for DC volts on the voltmeter
PC board.
• Check for 4.75 to 5.25VDC from
TP5 to lead #510C. See Figure
F.9
Note: The coating will have to be
removed from the test points to ensure
accurate voltmeter readings.
• If the display is NOT lit and the
correct DC voltage is present at
TP5 to lead #510C, the digital
meter may be faulty. Replace the
meter.
• If the AC voltage IS present at
leads #601 to #602 and the DC
voltage is missing, the voltmeter
PC board may be faulty.
7. Test Digital Voltmeter Accuracy
• Use a test meter with at least 3-
1/2 digits and +/- 0.5% accuracy.
• Connect the + probe to TP4 and
the - probe to lead 510C. Do NOT
disconnect plug.
Note: The coating will have to be
removed from the test points to ensure
accurate meter readings.
• With the NA-5 voltmeter reading
SET values of STRIKE voltage,
adjust the strike voltage control
until the test meter matches the
settings in the table below.
• If the NA-5 digital voltmeter does
not match the readings, the digital
meter may be faulty.
METER CIRCUIT ACCURACY TEST
(Continued)
NA-5
NA-5 SET VOLTS READING
TEST VOLTMETER READING
15.0VDC
.150 +/- .004VDC
30.0VDC
.300 +/- .004VDC
60.0VDC
.600 +/- .006 VDC