Nord User Forum

Dear all,

Since I transported my NE3 to the Philippines, two keys died. Disassembled everything and did a thorough cleaning ... no result. Changed the wires that went to the key contacts board ... no result.

I concluded the problem lies in the upper key contacts board. See pics below; arrows indicate the faulty key contacts.




What are my options? Can I order this upper contacts board?

Any advice/help would be greatly appreciated!

Thanks,

Matty

Have you tried bridging the contacts while the board is powered up to see if the tones are generated? two of those carbon contact pads look pretty worn so you might be onto something. Also there's a scratch running across those tracks at the botton of the first picture. Might be worth running a continuity test across each one with your multimeter.

mattydemont wrote:Changed the wires that wen to the key contacts board ... no result.

What do you mean with this exactly? Did you replace the ribbon cables between the keybed and the mainboard?

mattydemont wrote:I concluded the problem lies in the upper key contacts board. See pics below; arrows indicate the faulty key contacts.

Have you ruled out the diodes at those positions. Judging from the photos (though it is not entirely clear), the tracks on the PCB look fine to me at the areas you point out.

mattydemont wrote:What are my options? Can I order this upper contacts board?

Probably, but it will probably take some work to locate a replacement one. I'm not convinced you'll need a replacement though. If it is the diodes that went bad, they can be replaced (they're really cheap parts). If it is actually the PCB that was damaged (not very likely, you'd probably notice serious damage on the outside of your Nord if that was the case) you could theoretically fix it (by bridging damaged parts). If you intend to replace that part, you might as well attempt to fix it (nothing lost if you fail).

I think your best solution would be to find someone who's handy (enough) with a soldering iron and has a multimeter (this could be you ). Then check (measure) the diodes for the keys that have issues (follow the trace on the PCB from the key contact to the diode).

Have your already done some measuring, have have you just thought about it where the issue might lie (I think there's a good chance you are right)?

If you do intend to try and repair this yourself, I think you'll need:

• A multimeter
• Side cutters (electrician ones will do fine)
• Some (needle nose) pliers (not too big please)
• A desoldering pump (optional, but helps)
• Desoldering braid (can be a more time consuming alternative for the desoldering pump)
• Some 60/40 (or 63/37) rosin core solder (easiest to work with) or some lead-free solder; 0.5 to 0.8 mm thickness would be best, but 1 mm would work too
• And the most important bit: replacement diodes (say 5-10, gives you some room for error and any future repairs, if ever necessary) of the right type

A cheap soldering iron (one that just plugs into the wall socket) would work fine, provided it has a fairly small tip (ideally one that looks like a small screwdriver, say 2-3 mm in width). 15-40 watts should be fine, but 80-200 is overdoing it.

Edit: you won't need much solder and you can often get it in small tubes that contain 50-100 grams, which is plenty.

Good advice above -- it's either bad contacts or bad diodes. A replacement PCB should be available through your national distributor.

Pablo

Hi guys, thank you this is very helpful! As suggested, I did a bridging test which allowed me to trace the problem! I used the Hammond sound, which allows me to concentrate on the upper contacts only. Here is a pic of the bridging test:

https://dl.dropboxusercontent.com/u/200 ... idging.jpg

The dead notes are F4 and C#4. I connected the left to the right contact and then followed the right contact's circuit until I heard the sound coming through. For both faulty contacts, this only happens when I connect them (red lines) to the solder spot on the right indicated in the pic. If I bridge the two contacts as indicated in the pic through the yellow line, the two dead notes come alive! Hence, I blame it upon bad wiring in the PCB. I lived for six years in Senegal next to the ocean and that part of the PCB shows some corrosion.

Hence, bottom-line is ... it was neither bad contacts, nor bad diodes, but corroded PCB wiring due to harsh oceanic climate. Aside from the corrosion, I cannot really see any interruption if I follow the suspected wire. Look at the following close-up of the corrosion.

https://dl.dropboxusercontent.com/u/200 ... rosion.jpg

Looking at the corrosion, I guess I best try to source a replacement PCB, what do you think? I can repair this wire, but at some point other wires can become bad, no?

OK, cleaned the copper traces with a fiberglass brush and traced the problem to one single solder joint:

https://dl.dropboxusercontent.com/u/20043117/Solder.jpg

Since I don't have the proper equipment (my soldering iron has a big tip), I will contact an electronics specialist. Thanks for all the tips!

Nice work. Glad you diagnosed it. At least you should be able to get it working for little cost.

Salt-air climates are notorious for destroying pretty much everything. So long as you've given the boards (all of them) a good clean, you will give your Nord the best chance of surviving.

mattydemont,
Abrasive methods risk further damage to the traces so keep being careful! I don't know much about cleaning the corrosion off, it's not covered in the IPC-7711B/7721B PCB Repair Standard

I suggest a gentle wipe with a cloth dampened with distilled water to remove any residual salt. --It needs distilled water or you risk depositing more minerals/salts on the board.

Ask your electronics specialist if they have "solder mask" coating. This is the (usually) green coating that covers the circuit board. It helps prevent corrosion and keeps solder from flowing where you don't want it.
See PCB Coating Replacement for more repair information.

You can get the coating in a pen for small areas
green-overcoat-pen
or
In larger volumes if needed:
urethane-conformal-coating-4223

I know the last two links come from a reputable vendor, so if you decide to do this yourself and track down an alternate, you can at least compare it to this vendor to try to gauge the quality. If needed, post a link here and I can try to help.

Thanks for the detailed pictures and explanation of your problem and how you isolated it. Nicely done!
-pterm