Thermal Dynamics 51 CUTMASTER, Руководство по обслуживанию

Страница: 36 / 88

TROUBLESHOOTING 4-16 Manual 0-2972
C. Diode Testing Basics
Testing of diode modules requires a digital volt/ohm-
meter that has a diode test scale. Remember that even if
the diode module checks good, it may still be bad. If in
doubt, replace the diode module.
1. Locate the diode module to be tested.
2. Remove cables from mounting studs on diodes to iso-
late the module.
3. Set digital volt/ohmmeter to diode test scale.
4. Using the Figures for each test, check each diode in the
module. Each diode must be checked in forward bias
(plus to negative) and reverse bias (negative to plus)
direction.
5. Connect the volt/ohmmeter positive lead to the anode
(+) of the diode and the negative lead to the cathode
(-) of the diode for forward bias testing (refer to follow-
ing figure). A properly functioning diode will conduct
in the forward bias direction and indicate between 0.3
to 0.9 volts.
0.75
VR COM A
Art # A-00307
Anode
Cathode
Forward Bias
Diode Conducting
+
_
Diode Test Symbol
Testing Diode Forward Bias
6. Reverse the meter leads across the diode for reverse
bias testing (refer to following figure). A properly func-
tioning diode will block in the reverse bias direction
and depending on the meter function will indicate an
open or “OL”.
OL
VR COM A
Art # A-00306
Anode
Cathode
Reverse Bias
Diode Not Conducting
+
_
Testing Diode Reverse Bias
7. If a diode checks bad, replace the diode module.
8. Reconnect all cables to proper terminals.