2000XL encoder replacement - mystery wires?

My XL has the data wheel problem where you need to pull up on it the whole time to get it to register any movement. So I did my research, bought the part, watched some tutorials.

Got the part, took the MPC apart to do the job, and... the underside of the board has a bunch of wires in and around the encoder which I haven't seen in any of the repair pics and vids I've looked at.




Top of the board appears normal I think



Doesn't help that most of the forums in the world have busted pictures now, so you can't even see what people were talking about in repair tutorials from 10+ years ago.

Has anyone seen this before? Why are they there? Do they need to be there? Two of the wires are attached to what I assume would be the up/down contacts in the row of three on the encoder.

I'm very much an amateur at soldering, so the job was going to be daunting enough as it is without having to avoid half a dozen tiny wires around the job the whole time.

Lampdog wrote:Zoom in on the traces that are rubbed out and silver.

Those worn out traces are the SAME as the blue wires. Meaning someone previously reconnected those incomplete traces with wires. Those wires are from a repair somewhere in the past.

Yeah, could have been done at factory, or somebody else did a repair. Looks like an accidental burn on the board though... and likely a repair.

So for the fun question... is there an issue with the repair job... or is it the encoder? Uhm... might be able to get some understanding by checking the wires... or maybe using a multimeter... depends on how skilled you are or feel like becoming with electronics.

Edit: zooming into the picture you can see the attempt to repair those traces... oof. To my (old) eyes, and not having it in front of me... those traces look like it is quite possible that they don't connect... hence the blue wires being run for a repair.

Thanks guys, interesting that it may be a repair, and that it may even be factory?

And thankfully the problem is definitely the encoder, it gets pushed in and needs to be pulled out and it doesn't click at all. It only registers movement from very careful turning while pulling up on it, and it registers up and down scrolling consistently while doing that. So I guess all the connections these wires are making are doing their jobs.

I guess I'll just carefully avoid the irrelevant wires, do the encoder replacement, and reattach those same wires. I can see myself really opening a can of worms here though.

You'll see stuff like this a lot on older gear especially... producing those older boards was sometimes hit or miss, and it used to be *much* cheaper to just repair defects like this because they'd have a soldering engineer on staff who could do patch jobs. To me it looks like an odd defect... and botched initial repair... it's possible it went in for repair and somebody dropped some acetone or something by accident that damaged it. Totally sucks, but older gear like this is actually easy to repair like that since you can see all the traces much more easily. Definitely keep those pics around for posterity though... if one of those wires ever comes loose it'll make it easier to figure out where it was supposed to go.

Given your descriptions of the knob problems... yeah it sounds like the knob replacement is the key. If I had to guess... looking at the picture you or a repair technician will need to make sure two of those wires are reconnected properly. Anyway... good luck in getting it back in working order!

I guess nowadays there's less chance of seeing this because it would be a lot smaller and harder and more expensive to do, and a lot of stuff is built with generic off the shelf components produced by the millions, like for the MPC Live etc. So not worth trying to save it when you can replace it.

Despite the odds, I succeeded. Desoldered the original, but took off one of the pads and I thought I was screwed. But that was one of the pins with a wire, so it didn't need the trace anyway. Got some good solid connections on the two main brackets for strength, and reconnected the two wires. Turned it on and it scrolls up and down beautifully.

The need to pull up on the faulty encoder is clear once it's out. The rotating stalk was punched clean through the unit, and just spins pointlessly. Pulling up on it engages it where it's supposed to be, and you can feel the clicks. Crazy they entrusted so much crucial function and wear and tear for the whole machine on this tiny piece of plastic. If they had spent a few more cents on nicer ones back in the day, it would have saved a lot of people a lot of trouble. Or they could have designed it so pushing down on the wheel doesn't put all that force through a millimetre of plastic.

Well done with the repair, glad it worked out for you man!