Remove Faulty Onboard Bridge (V1); Install New Onboard Bridge (V1) - ABB DCS800 Service Manual

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Remove faulty OnBoard bridge (V1)

1. Follow the instructions Remove faulty thyristor modules until step 8 is done.
2. Remove all connectors from the faulty OnBoard bridge and mark the
connectors clearly.
3. Remove the faulty OnBoard bridge and mark it clearly as defective.

Install new OnBoard bridge (V1)

1. Ensure that the new OnBoard bridge is of the correct type ( see appendix A of
this manual).
2. Remove old heat conducting compound (grease) from the heat sink. Clean the
mounting surfaces (heat sink and OnBoard bridge) with an appropriate solvent
(e.g. ethanol) by means of tissue paper. When the heat sink is clean, spread
out the heat conducting compound with a rubber spatula or by hand.
3. Apply a thin layer of heat conducting compound to the new OnBoard bridge.
4. Spread the heat conducting compound evenly by moving the OnBoard bridge
forward and backward on the heat sink.
5. Tighten all clamping screws by hand until the screw heads touch the bottom of
the thyristor module. Then tighten the screws to 2.0 Nm torque.
6. Tighten the screws to nominal torque according to table Nominal mounting
torque for OnBoard bridge and thyristor modules on page 35.
7. Reconnect all connectors to the OnBoard bridge.
8. Follow the instructions Install new thyristor modules beginning with step 10.