Replacing a Fuse


Welcome. In this video, we will go over fuse replacement for a Compact FUSION SCR Power Controller.

You will need the following:

  • A #2 Philips bit screwdriver
  • A small flat head screwdriver
  • If you are working with a 10 - 50A controller, you will also need a pair of fuse-pulling pliers.
  • A 80 - 160A controller will call for a #3 philips bit and a torque wrench.
  • You will also need some electrically-conductive anti-corrosive paste, like Penatrox A, and the replacement fuse or fuses - these are available for purchase from Control Concepts

Before replacing a fuse, you must turn off line power and control power. Then use a screwdriver to remove the controller lid. Disconnect the display wire and set the lid aside.

Now, remove the main wire harness by pulling very gently on the connectors - not the wire itself. 

You will also need to remove the flat flex cable as shown. Pull the key toward the cable from both edges of the connector. The key tabs will stay attached to the connector.

Remove the four screws in the corners of the gate driver board. Gently lift the board out of the controller.

Now the steps vary depending on your controller size. A 10-50A Compact FUSION is pretty straightforward: simply remove and replace the fuse. We will focus more on the 80 - 160A sizes.

These controllers have fuses attached to insulators. Here is a 160A controller - we remove the screws, paying attention to how the bus bars, wires, and lugs are oriented.

An 80A controller also has a DVDT board that must be removed from the SCR to get to the bus bar.

Once you've removed the bad fuse, take the new fuse and apply a thin layer of conductive anti-corrosive paste where it contacts the lug and the bus bar.

Insert the fuse, reattach the red wire with the ring terminal, and the lug. Torque the screws holding the fuse to 75 in-lbs.

For an 80A controller, you will do the same: torque the screws around the fuse to 75 in-lbs, and then re-attach the DVDT board and torque the stand offs to 25 in-lbs.

Now we continue working backward: Connect the leads from the current transformer. Re-insert the gate board with the 4 screws, and keep the board supported and not over-stressed while you connect the installation displacement connectors. Next, connect the flat flex cables, starting with the shortest. Be sure that you insert these cables into the key evenly - they should not be crooked or below the key altogether.Re-connect all the wiring to the correct headers, as well as any fan wires if present. (say 2x, once without) Reconnect the display cable. Re-attach the controller lids. Finally, apply control and line power and make sure a blown fuse indicator is NOT present.

For more information or assistance, download the Compact FUSION Installation manual from our website at or contact the experts directly by calling Control Concepts, Inc.