Service infos
03 / 2002 IGBT gate resistors and intermediate circuit charging relay
Power sources
Minarc 110 & 140
Modification
IGBT gate resistors (10 ohm.) have been added to the spare part set (4297750).
Reason for modification
If the IGBTs are damaged, also the gate resistors (R2, R4, R5, R6, R7 and R8) may be damaged.
For example if one resistor has been destroyed, then the IGBT doesn´t get gate control and this
causes overload to the other IGBTs. When IGBTs are replaced then the gate resistors must be
checked too. See the attached picture.
DC-link(Intermediate circuit) charging relay K1 (9766230)
If fan rotating speed drops after the machine starts and the OCV is max. 85 volts, then most
likely the DC-link charging relay is not working. In some cases there has been lacquer inside
the relay and it is stuck. Relay control voltage is approx. +28 volts.
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