
3-29
M
AINTENANCE
Service Manual
TP8
TP1
TP2
TP4
TP6
TP3
TP7
TP9
P3
TP11
TP16
TP19
TP20
TP18
Figure 3-6 Control Board Test Points and LED Locations
Test Point
Description
Value
TP1
Transfer signal.
A logic high (12V) indicates that the arc is transferred.
TP2
Start signal.
A logic high (12V) indicates that the torch start switch is on.
TP3
GND
TP4
+12V
TP5
Unregulated DC voltage.
Approximately 30VDC at nominal input voltage.
TP6
+18V
TP7
INV-ON signal.
A logic high (12V) indicates that the inverter is on.
TP8
Transfer latch signal.
A logic high (12V) indicates that unit is in transferred mode.
TP9
Temp OK signal.
A logic high (12V) indicates that all temperatures are OK.
TP10
Continuous PA threshold voltage.
Set to 3.55V by P3.
TP11
7.0V
TP15
Error amplifier reference voltage.
During inverter operation this signal is 1.915V at 50A current
setting and .75V at 20A current setting.
TP16
Error amplifier output voltage
TP17
Reference voltage
2.50V
TP18
Output current value signal
38.3mv/amp
TP19
Wiper voltage.
2.5V at 50A current setting and 1.00V at 20A current setting.
TP20
GND
TP21
Buffered, inverted, capacitor feed version of pulse width modulator B signal.
TP22
Buffered, inverted version of pulse width modulator A signal.
Fuses
F1,F2
Cap sensor circuit protection
.5A (see Parts List for part number and specifications)
F3,F4
Start circuit protection
.5A (see Parts List for part number and specifications)
Control Board Test Points
9-96
D24
D25
D26
D27
D15
D8
D29
D35
TP15
D42
TP17
TP21
TP22
TP5
TP10
D38
F1 F2 F3 F4