Encoder repair problems

[RoycePC]

Hi - first post after spying on you all for a while.

I am trying to fix a secondhand Behringer BCR2000 Midi controller.
It has erratic  encoders (some switched, most not) and some feel a bit tight. Too many cokes in the studio is my guess.
My usual encoder fix is to "dribble" some contact cleaner/lube between the shaft and the bush on the encoder case.
Worked a treat, but 3 days later after the cleaner flashed off, I guess, is was as bad as before.

Tried this a few times, fixing the problem then leaving the unit with the case on its side hoping the crud inside would pool outside the encoder area. No luck
I opened the BCR up and took out a couple of what look like Bourns PEC11 stripped them, found what looked like oil pooled in them and cleaned / washed them in isopropyl alcohol.
Reassembled and put them back in and they work perfectly. Three days later...... 
 So I am at a bit of a loss as what to do next.

I have heard that there should be some lubricant in them. Is this where I am screwing up?

Royce

[Audiorepair]

You'll probably have to replace them, they wear out.

You can usually find one in the below search that will fit by measuring yours and comparing it to the datasheets.
Sometimes you might have to cut the shaft down a bit, or use one that doesn't have a threaded bush for mounting, or vice versa, or one with detents with non detents or a different number of them etc.

Or see if you can find a thread where someone else has done this and can supply a part number.

https://uk.farnell.com/w/c/automation-process-control/motors-motor-controls/encoders-accessories/rotary-encoders?push-switch=with-push-switch


(Link edited to show more items than those from Bourns)

[RoycePC]

Thanks for the reply.

I was really interested in knowing what was happening to the encoder.
It seems that after the cleaning fluid is applied it works perfectly and then when it flashes off that is no longer the case.
Initially I though it was that the 'contact cleaner' was leaving a lubricant that was interfering with the contacts, but as the alcohol clean should not leave a residue that doesn't seem to be the case.
Does anyone know what is happening inside these critters?

Is the spring pressure of the wipers just dropping off?
Is the cleaning fluid offering a conductive path to the contacts?
Is the fluid lubricating the wiper and so reducing contact bounce?

Royce

[David_AVD]

I would just replace them. They are cheap and pretty easy to get from Mouser, etc.

[RoycePC]

Thanks for the help.
Unfortunately the controller has 8 switched encoders and 24 non-switched ones.

I have fixed many other of these mechanical encoders (the Alps exploded diagram on their website looks exactly like the ones in this BCR2000 rather than the Bourn ones).
Even if they are failing, I don't understand their failure mode.
I can bring them back to good as new with a few drops of volatile cleaner , but only for a few days, even with no use.

I'll see if I can get some new ones.
Thanks again for the help.
Royce

[David_AVD]

Get yourself a can of Innox MX3 from Altronics or Bunnings. It is quite effective at cleaning up intermittent switches and pots.

[RoycePC]

Thanks everyone for the help.
Stripping the encoders and cleaning them with Shellite (I think this is called Colmans fluid in the US) - which I'm told is the base of Deoxit 5 without the secret deoxidising agent-  and then using a small amount of Inox Mx3 worked a treat.
I have no idea why the previous owner put a lot of thick oil in the encoders, but they now have been working for a while so I hope all is well.
Thanks again

[floobydust]

I went through this with Onkyo AV receiver volume control encoder. In the end, I gave up cleaning/DeOxit/lube because it still never worked well after all that hassle.
I took the encoder apart and found it was simply worn out on the stator. Once the factory grease is gone, it quickly dies. The wear gives more switch bounce than the firmware could handle, it couldn't make sense of it being turned in what direction. They appear to have a 15,000 rotation life spec. but I find Behringer is using low cost parts I end up replacing many potentiometers and electrolytic capacitors in them.
I would just get the Alps part for $2 and not look back.

[rkabz]

Pictures attached of budget encoder in bits. Better quality ones have bifurcated wiper 'blades' with gold or silver plating. This one is plain old stainless steel. The wiper blades are twisted so present a sharp edge to the stator, wearing it out in fairly short order. This particular encoder was in a TENMA power supply only a couple of years old. The PSU was almost unusable because the voltage could not be set. Replacing the encoders was the only option. In another instance of a poorly performing encoder (quality Japanese brand) found in a Cambridge Audio power amplifier, it turned out that the lubricating grease had dried out and hardened over time, but the contacts were still in good condition. Cleaning out the old grease with iso and using a very light contact lubricant fixed it. It's been OK for 4 years since I did this.