Danfoss VLT 3032 Service Manual page 31

REMOVING AND REPLACING
GATE CARD, SNUBBER BOARD
AND IGBT
ESD Caution IGBT
Electro Static Discharge (ESD) can have
damaging effects on
components. The IGBT gate connection
is sensitive to static electricity. Whenever
the gate leads are disconnected from the
gate card or IGBT, the gate lead terminals
must be shorted together. This can be
accomplished with test leads or by
inserting small jumper wires in the ends
of the gate lead wire connectors.
GATE DRIVE CARD
1. To gain access to these assemblies remove the Control Card/
Interface Board Carrier. This is done by loosening the two captive
screws on the left side of the Carrier. Slide the carrier towards the
top of the unit and lift out. There is ample cable length to allow the
Carrier to rest in the bottom of the unit.
GATE DRIVE CARD
2. Remove plugs MK1 through MK9 from the gate drive card. Note:
Coded plugs and the wire harness arrangement insure all plugs
can be returned to the correct location.
3. Working around the board, release the eight swag clips with the
use of needle-nose pliers. Lift the board free of the swags as you
go.
Reverse the procedure to replace.
IGBT SNUBBER BOARD
4. Remove the nine Phillips screws securing the IGBT Snubber Board.
NOTE: This is a good time to statically test the Snubber Diodes.
See testing the Snubber Diodes on page 26.
Reverse the procedure to replace. Torque to 15-19 LB-IN (1.7-2.15
NM).
IGBT
5. Remove the three (3) Standoffs (13mm) securing the Bus Bar and
the Motor Coil Wire to the IGBT to be replaced.
6. Loosen the remaining Standoffs, but do not remove, on the
remaining two IGBT's. This should allow sufficient clearance to slide
the IGBT from beneath the Bus Bar.
7. Remove the two Phillips screws securing the IGBT to the heatsink.
sensitive
Reverse the procedure to replace. Prior to installing the IGBT,
apply silicon grease 3 mils thick to the entire base of the module.
Transfer the gate wires from the replaced IGBT to the new IGBT
insuring correct polarity. Upper set (E2-NEG, G2-POS), lower set
(E1-NEG, G1-POS). Alternately torque the IGBT mounting screws
initially to 8-10 LB-IN (.90-1.13 NM), final torque to 22-26 LB-IN
(2.49-2.93 NM).
Replace the standoffs and insure all standoffs are torqued initially
to 8-10 LB-IN and finally torqued to 15-19 LB-IN (1.70-2.15 NM).
IGBT SNUBBER BOARD
32
IGBT'S