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  • Author Author: shabaz
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Obsolete Potentiometer Controls: 3D Printing to the Rescue!

shabaz

I suspect this is a common problem; lots of old Hi-Fi equipment have worn out pots and other controls, and it can be quite difficult locating exact replacement parts.

A friend had a music device (It’s a sort of DJ CD player with a lot of controls) around 30 years old, and it had a really worn down front panel. The controls were scratchy to operate, and in some cases, the grease had hardened, and the controls were very stiff. Some controls didn’t work, and others were crackly. Someone had already tried to clean it with a can of WD40.

Ordinarily I would turn down such a repair request, but it’s a friend, and he was pretty passionate about this particular device, he had no desire to replace with a modern digital solid-state music player. I decided to fix it, and ran into the problem that I simply couldn’t find alternative potentiometers that would precisely fit.

I briefly considered reverse-engineering the entire front panel board to rebuild it from scratch, but that would have been a lot of work. I decided to focus on the potentiometers instead.


I searched around and found some potentiometers that had the correct shaft (my friend didn’t want the plastic knobs to be altered from the original ones), but the potentiometers themselves were a lot smaller. After some brainstorming, I realized that I could make a little plastic adapter, and use a flexible PCB to route the pins of the potentiometer to match the original potentiometer.


I designed it using FreeCAD (I am still a learner, hence the design is simplistic).

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I don’t own a 3D printer, so I had to use a 3D printing service (I used J.L.C.), it was surprisingly low-cost. I chose to print in nylon, which is quite tough and reasonably heat-resistant.

I designed the flexible PCB using KiCad, and again used the overseas manufacturer to order it. See  Creating a Flexible PCB!  

For the potentiometer pins, I used 2.54 mm pin headers, and pulled out every other pin since I needed 5.08 mm spacing.

image



For the slider potentiometers, I did a similar thing, only I was able to use a normal PCB instead of a flexible one:

image


And here’s the final result! I used epoxy glue to fix the rotary potentiometer into its new 3D printed housing, and to attach the slider pot PCB onto its 3D printed base.

image

One down, about 23 more to go!

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Thanks for reading.

Parents

  • Absolutely awesome!
    I think you should invest on a 3D printer. You will love it! Get a Bamboo lab or Creality. Bang for the buck!

  • in reply to aswinvenu

    100% agree. I bought a Bambu Lab A1 Mini for £169 last month (it got discounted a further £20 last week in their anniversary sale!). It's been brilliant.. totally plug & play.

    I've been learning Onshape, since I wanted a CAD tool I could use in a browser across computers easily.

    You end up using it a lot more than you think.. little thing breaks; quickly print a new one!

  • in reply to Matt

    Hi Matt,

    Wow I didn't realise they had come down so much in price! Since you and  and  are all mentioning Bambu printers I'm going to strongly consider it. I did actually make a mistake in my 3D model, fortunately one easy enough to fix with a file or craft knife, otherwise all 24 of these pot adapters would have been scrap! I took a risk to trust I had it right first time.

  • in reply to shabaz

    I would recommend Bambu too. I had been using Ender3 V2 for 3 years but recently got my hands on Bambu Lab A1. It is much faster, has better print quality and has whole lot of advanced technology like vibration and noise compensation.

    There was an anniversary sale going on Bambu website, I think it's still on for a day or two, you may check that.

  • in reply to rsjawale24

    Yeah, the A1 Mini is still £149 in their sale. Very reasonable IMO.

    In some ways I wish I'd bought one sooner.. like when my kids were little; I could imagine so many things I could have printed for train sets & that kind of thing! However, back then it wasn't as straight forward to print things, and now's the time it's almost becoming a household item.

    This weekend I'm sorting out our kitchen pan storage with a bunch of custom designs & prints that exactly match what we've got. That's the exciting life I live! Slight smile

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  • in reply to rsjawale24

    Yeah, the A1 Mini is still £149 in their sale. Very reasonable IMO.

    In some ways I wish I'd bought one sooner.. like when my kids were little; I could imagine so many things I could have printed for train sets & that kind of thing! However, back then it wasn't as straight forward to print things, and now's the time it's almost becoming a household item.

    This weekend I'm sorting out our kitchen pan storage with a bunch of custom designs & prints that exactly match what we've got. That's the exciting life I live! Slight smile

Children