For Anyone Needing to Replace Encoder on Agilent 54831 Oscilloscope

[bostonman]

For anyone who needs to replace a rotary encoder on an Agilent 54831M oscilloscope, the 25LB22-Q encoder seems to be a great replacement.

After research and with the help of others on here, this seems like an excellent replacement. The visible differences is the replacement has a slightly shorter shaft (maybe 2 mm) which doesn't affect the plastic knob, but may have a slightly thicker shaft. The plastic knob on mine was also missing and I'm in the process of 3D printing a replacement, so this isn't an issue for me. Maybe the shaft will need to be filed slightly to fit the original knob (?) for anyone who replaces this and uses the original plastic knob.

The electrical differences is needing to physically connect wires from the PCB to the encoder due to pin differences (see my attachment for notes).

Also, the replacement has a plastic tab that fits into a rectangular hole on the PCB to keep from moving. The replacement encoder needed to be filed slightly to fit, but also needed a dab of hot glue due to the width being slightly narrower; I'm assuming the original fit tighter.

Testing showed it has almost the same level of clicking sound, just about the same force to turn the shaft, etc...

If you wire this and for whatever reason it's reversed, I believe just swapping pin 1 and 3 on the PCB will solve it.

This board has two types of encoders, the black shaft has detents and the blue shaft doesn't. Unfortunately I didn't see an option for this encoder to not have detents, so I don't have an answer on replacing the blue shaft ones.