Fixing the Align 5.1 Voltage step down

Author: Rob Turnbull
Article Date: 12th February 2008

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Early in 2008 I had an in-flight failure which caused my 600n to pirouette on its own. I managed to land the helicopter without damaging it and after close inspection of the rudder servo (my first guess as to what might have failed) I realised that was not the fault. I then went on to find the culprit, which was the Align 5.1 voltage step down that sits between the gyro and the rudder servo. The positive lead had become disconnected from the diode inside the red heatshrink and consequently, the rudder servo had stopped working due to not being fed any power.

Even though these items are cheap to buy, fixing it is very simple, and the lesson learned here is to add a little damping around the soldered joints, as you will see below.

The first picture below shows the broken wire and I have revealed the leg of the diode by slightly cutting and then peeling back the red heatshrink.

  • Broken positive wireBroken positive wire
  • Tin the wireTin the wire

The second picture shows the newly tinned positive wire. I removed a small amount of the wire sheath, then tinned the wire ready for reconnecting to the diode.

The next step is to solder the loose wire back onto the leg of the diode.

  • Reconnected positive wireReconnected positive wire
  • Add silicone around the soldered joint and wireAdd silicone around the soldered joint and wire

I then folded the red heatshrink back into place and liberally added some silicone around the wire - having let it cool down first. With the silicone in there, it creates a nice damping effect so this wire should not be able to break free through vibration any more.

Hot glue would also be a good choice to achieve this damping effect.

Next, remove the positive lead from the black plug by lifting the little clip on the plug and pulling the wire out. Slide some heatshrink over the newly connected wire and diode, and shrink it.

  • Remove positive lead from the plugRemove positive lead from the plug
  • Apply heatshrink to the re-connected wireApply heatshrink to the re-connected wire

Plug the positive lead back into the plug and thats the job done!

  • Fixed 5.1 voltage step downFixed 5.1 voltage step down

It would be a good idea to add damping (hot glue or silicone) to both sides of the diode, not just one as is shown here - I have done this now, but did not when taking the pictures...