Orion and Orion II small encoders - replacement sources and installation tips

The six small encoders used in the Orion and Orion II are no longer available and the non-exact replacement encoders offered by Ten-Tec service are expensive. There are no exact replacements available on the market with a 25mm shaft length, 6mm diameter round shaft, and integrated switch. If you're unable to obtain exact replacement encoders, the Bourns PEC11L-4225F-S0015 and PEC11L-4125F-S0020 encoders are offered by Mouser. They work okay, with detents (clicks) as you turn them, but with a bit faster action than the originals. I used the S0020 encoder but believe the S0015 would be slightly preferable with a slower pulse rate. There may be two pulses per detent so it can be tricky setting the value precisely, between detents. If you know of another encoder source, please contact N1EU so this page can be updated.

Caution: do not attempt encoder replacement unless you are capable and confident in doing the disassembly and PCB component removal. This is a fairly involved disassembly and fairly demanding component removal/install.

Consult front panel disassembly instructions and RIT encoder changing instructions given by K4ZNO.

In terms of removing the old encoders from the PCB, here's what I did:

  1. I used a solder sucker and 750F iron, and hit every encoder pad - apply the iron for a minimal amount of time to avoid overheating/damaging the pads. After this step, you should see light shine through the two pads on top and the outside two pads on the bottom of each encoder. You won't see light through the middle pad on the bottom or the two side pads, because these three are connected to the ground plane (big heat sink).
  2. Cut all terminals from the body of the encoder, as close to the encoder as possible to leave as much terminal length connected to the pad as possible.
  3. The four terminals (with light shining through) should come right off the pads. Use solder iron and needle nose pliers to remove the 3 ground terminals remaining from each encoder.
  4. Hit the ground pads with solder sucker again to clear the holes. If they still won't clear, use a sewing needle or sharp probe while heating the pad to clear the holes. You need to end up with all 7 holes fully cleared on each encoder.
  5. Use flux removal pen or q-tip dabbed in acetone to clean the board/pads.
  6. Carefully prep each encoder for insertion - the 5 small pins should be straight and aligned. In order to get the larger side pins to fit their holes, I worked the pins with long nose and needle nose pliers to end up with 10mm separation between the ends of the pins. I also "squashed" the crook out of the pins.
  7. Carefully place the encoder over the holes and confirm all pins are aligned with the holes. I tended to rock the encoder up and down slightly between the 3 and 2 pin sides to confirm they were inserting freely. I exerted slight pressure with those 5 pins inserting downward, while rocking the encoder carefully side to side to get the larger side pins to seat. You should end up with the encoder body square and flush with the PCB. Watch the side pins closely and if one is not seated properly, you'll see the metal push away from the plastic encoder body. Just pull the encoder out and realign the pins and try again. You'll get the hang of it after one or two.
  8. Follow K4ZNO's excellent advice of mounting the encoder PCB back on the display board to insure proper alignment of the encoder shafts before soldering. Note that the nylon nuts securing the encoders are only finger tightened - don't use a nut driver or wrench on them. The alignment of the encoder shafts is fairly critical in order to avoid binding/friction at some point in the shaft rotation.

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