Thermal Arc ARCMASTER 300 AC/DC, Service Manual

Page: 56 / 116

300ACDC
11
ADVANCED TROUBLESHOOTING
11 – 11
5
Verification of the Power
Input Circuitry
CAUTION
Before performing any portion of the procedure
below, make certain the unit is placed in the initial
set up condition as described
in section 11.4.1
"Preparation".
5.1 Verification of the AC Input
Voltage using an AC Voltmeter
1) Verify input voltage (Phase-to Phase) using an
AC voltmeter. (The capability of the voltmeter
should be more than 600VAC). Measure the
point between lines U1 and V1 on the input
switch, S1.Measure the point between lines U1
and W1 on the input switch, S1. Measure the
point between lines V1 and W1 on the input
switch, S1. The location of points U1, V1 and
W1 on switch S1 are indicated in Figure 11-7.
When using a single-phase connection, the
voltage can be verified only between U1 and
V1.
Figure 11-7: Check points U1, U2, V1, V2, W1 and W2
2) If the input voltage is out of the operating range
of the unit, which is
±
10% (187
-
253/414
~
506
VAC) of the rated voltage (208, 230/460V),
verify the available power capacity at the
installed site. If the input voltage is within the
operating range, recheck the input voltage
while welding, as welding may cause the input
voltage to decrease to a value below the oper-
ating range of the unit.
3) Verify input voltage after the input switch (S1)
using an AC voltmeter. (The capability of the
voltmeter should be more than 600VAC.)
• Using an AC voltmeter, measure between
the points U2 and V2 on the input switch, S1.
•
Using an AC voltmeter, measure between
the points U2 and W2 on the input switch, S1.
• Using an AC voltmeter, measure between
the points V2 and W2 on the input switch, S1.
The location of points U2, V2 and W2 on
switch S1 are indicated in Figure 11-7. When
using a single-phase connection, the voltage
can be verified only between U2 and V2.
4) If this voltage is out of the operating range,
which is
±
10% (187
?
253/414
?
506 VAC) of
the rated voltage (208, 230/460V), replace S1
following the process in section 12.3.26.
5) Verify the rectified output voltage of the input
diode, D1 using a DC voltmeter. (The capabil-
ity of the voltmeter should be more than
1000VDC.) Using a DC voltmeter, measure
between the points 1 (P)[+] and 2 (N)[-] on D1.
Points 1 (P) and 2 (1) are on D1. See Figure
11-8. The measured voltage should be approx-
imately 1.4 times larger than input voltage
measured in #1 above. Replace diode D1 if the
calculated measurement is not within the cor-
responding range (260
?
360/580
?
720 VDC)
following the process in section 12.3.31.
Figure 11-8: The check points 1 (P) and 2 (N)
S1
U1
V1
W1
V2
U2
W2
D1
1
2