Thermal Dynamics CUTMASTER 60i Service Manual page 50

CUTMASTER 60i
5. Inverter Board IGBT Test. Measure J305-3 to GND PRI.
Art # A-13330
a. With meter on diode scale place + lead on GND PRI and – lead on J305-3. Normal reading should be two
times that of a diode in the forward direction, as it is measuring 2 diodes in series. (About 0.6V to 0.7V
with Fluke.)
b. Half of that, one forward diode, while rare, may indicate one shorted IGBT. If that is the case replace the
Inverter board.
c. Lower resistance/voltage including at or near zero indicate shorted IGBTs, replace the Inverter board.
d. If the reading is higher or slowly increasing, capacitor charging, you may have mixed up your + and –
meter leads. Reverse them and if the reading is still high, high in both directions, indicates open IGBTs,
replace the Inverter board.
5-16
3Ø
1Ø
MOV304 MOV305
GND PRI
BRIDGE+
TP8 TP23
15 UV LO LINE
J302
TP22
D302
HI LINE
TP4 TP21
BUS CHK +15V PRI
ACINSEN
D303
1 C301
C300
1
T301
C303
+15V
J303
+
6 4
+24V
3 1
HS302 D304
C305
D307 -15V
C307
SERVICE
E300
CHASSIS
GND
GRN/YEL
MOV300 MOV301 MOV302
1
K300
MOV306
R300 R301
1
T300
R302 R303
C302
J305
J304
1
1
Manual 0-5475