Nord Lead 3 Values Jumping (Arp, Glide, Unison), LCD shows potentiometer values changing randomly

[ghoulian]

Hi all! I picked up a Nord Lead 3 with an issue that's puzzling me. The display shows the parameters that the potentiometers control are being constantly changed (Arp, glide, unison).

After a few turns to 0 or 127 it relaxes, but returns to the previous state after a restart. I've replaced the 3 pots and the behavior is still present.
If there's anyone here who might have any clues, I would be so greatful!
I was hoping to repair this to keep for myself, but I'm still an amateur, and this has been puzzling me!

Short videos of what I am seeing:

[Angelo K]

Hi, I noticed that I also have the same problem with my Nord Lead 3.
I haven't used it for about a year, and last week after turning it back on I noticed this strange behavior: all the potentiometers on the LCD panel change value by + - 1, and I noticed that these values ​​are also sent via midi (CC).
Basically all the potentiometers of the Nord Lead on the left, including ModWheel and Pitch Bend.
I found the wiring diagram, I would like to try replacing the 2 10uF capacitors and see if the problem will go away.
Unfortunately I have little time this week, but as soon as I can I will try to change them.
I also tried replacing the 10Kb potentiometers, but nothing has changed. My suspicion goes towards the two capacitors.
If any other user encounters the same problem it would be appropriate to collaborate and find a common solution.

[ghoulian]

Hi, I noticed that I also have the same problem with my Nord Lead 3.
I haven't used it for about a year, and last week after turning it back on I noticed this strange behavior: all the potentiometers on the LCD panel...

Wow thank you for your response! I was starting to lose hope on a possible solution. I really hope this turns out to be the fix! I'll order in some capacitors as well, and I can give it a go too Btw, could you share the wiring diagram here if possible?

[Angelo K]

Hi, here are several Clavia schematics, you should enter the password written at the bottom of the list. ( All "Schematic" PDFs are password protected. The Password is: #nord)
In the Pdf Schematics there are two versions of the LCD panel ( Nord Lead 3 and Nord Rack 3 ), you should see in your PCB which version you have (I have 1.41), I noticed that some parts are different (also the values ​​of the capacitors that I should replace).
Update me if you can do the test.
Regards

https://bespin.federalproductions.com/m ... rd-Clavia/

[ghoulian]

Hi, here are several Clavia schematics, you should enter the password written at the bottom of the list. ( All "Schematic" PDFs are password protected. The Password is: #nord)
In the Pdf Schematics there are two versions of the LCD panel ( Nord Lead 3 and Nord Rack 3 ), you should see in your PCB which version you have (I have 1.41), I noticed that some parts are different (also the values ​​of the capacitors that I should replace).
Update me if you can do the test.
Regards

https://bespin.federalproductions.com/m ... rd-Clavia/

Thank you! I've taken a look and it makes a lot of sense that C4 would be a prime suspect. I actually poked around inside with an ESR meter, and C4 is showing a high ESR for me. I've got new caps coming in Saturday, and the first thing I will do is replace C4 and test! I will also try with C3 if that doesn't work.

[kotatsu]

Hi everybody and thank you for this thread.

If it is not too much of a burden for you, would you mind taking a few photos of the process of replacing the capacitors? It's always nice to learn and to eventually have a place to look in the case a similar problem arises.

[maxpiano]

Hi everybody and thank you for this thread.

If it is not too much of a burden for you, would you mind taking a few photos of the process of replacing the capacitors? It's always nice to learn and to eventually have a place to look in the case a similar problem arises.

They are standard SMD (surface mounted ) capacitors, if you know how to solder/desolder SMDs it is nothing special, if you don't... well, I wouldn't try it on an expensive keyboard as a first time.

[ghoulian]

Angelo, I replaced C4 and didn't see a change in the behavior. C4 also seemed to be in good shape once i took it out of circuit to test. C3 is a bit tricky to get to, so im going to hold off on trying to replace it for now. Could you give it a shot as well when you get the chance?

[Angelo K]

Hi, unfortunately I haven't had the chance to try, I'm out for work and I have other repairs to do as soon as I get home.
So from what you say, replacing C4 hasn't changed anything at all....very strange then.
To remove C3 from the PCB I would do it with 2 soldering irons, each with its tip on a separate pin, it should come off in a couple of seconds, being very careful of the plastic parts near them (but I would cover them with Capton tape, or other covers, such as aluminum foil to protect the rest.).
Another system is to use pliers and slightly rotate the cylinder of C3, so as to break its pins, which will remain soldered to the board and which you can remove very easily with the soldering iron and copper braid ( you can see many videos on youtube about this trick..)
If even replacing C3 doesn't change anything, I would go and check if the 5v voltage is constant in that branch, and as a last test I would try to isolate the pitch bend, because I know that in many Nord keyboards it has given a lot of problems.
Nearby, under the capacitors there is also the multiplexer, if you notice well it would be the integrated circuit that receives the signals of all the potentiometers and then sends the data to the motherboard through the external cable (try cleaning the contacts with deoxidizer on both connectors on the LCD panel side and on the MAIN PCB side).
As soon as I get back, I will do other tests, but I think it is necessary to pay more attention with an oscilloscope if with these checks just mentioned the situation does not improve.
Best regards

[ghoulian]

Thank you so much! I'll keep posting updates here as I try the things you mentioned