Mitsubishi Electric CITY MULTI PQRY-P200YMF-B Service Handbook page 86

Power transistor
Measure resistances between each terminal of transistor module with tester, and use the results for troubleshooting.
Specified resistance value is dependent on tester type to be used for resistance measurement, because diode
transistor has non-linearity, thus difference of impedance and voltage in tester being influential. As the internal
impedance of resistance range of analog tester equals to the center value of meter indication, the affect of internal
impedance can be minimized if the tester having close center value of resistance range. Because internal voltage is
normally 1.5V, the tester to be used for troubleshooting of transistor module should satisfy the following conditions.
Internal voltage
Central value of resistance range
The measured values for troubleshooting are shown in the table below.
(Use the minimum range for tester resistance range.)
C1
B1
E1
B2
E2
E2
Diode stack
Perform continuity check with tester. Judged as normal if the following characteristics are observed.
(Use the minimum range for tester resistance range.)
1 2
1
2
3
1.5V (Power source : one dry cell battery)
10 ~ 40Ω
C2,E1
3
+
–
C
B
E
Tester
Tester -
C
B
E
Tester -
Tester
–83–
Transistor module has 6
circuits shown in the left.
(See figure below)
⊕
C B
∞
2~100Ω 100~1500Ω
2~100Ω 100~1500Ω
⊕
Tester
+
1 10~50Ω
2 10~50Ω
3 10~50Ω
Tester -
+
⊕
∞
1
∞
2
∞
3
E
∞
–
∞
∞
∞
–
10~50Ω
10~50Ω
10~50Ω