A really bad 'off key' note

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What is your piano brand and type?
Damage to the contact rubber can cause note plays loudly or,
note does not plays at all.
It is caused by:
1. Carbon rubber contacts dirty / dusty (yellow arrow). Clean with a pencil eraser (or cloth). Gently rub it.



2. Contact rubber is torn (your case). If this happen,it can not be repaired or glue. So, you have to replace one octave.
The yellow arrow indicates the side that is often torn.

Rubber side that is torn, usually not seen, unless we move / pressing gently on top (In the rubber contact position is not installed on the board.)
Examples of this picture was yamaha psr.

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On organ mode, in general, almost all brands of the modern keyboard, velocity setting is not enabled. Setting velocity is used to determine how much the level of the sound that follows how strongly you press the keys. It is really just to imitate the sound of vintage organs, which in the past, electronic organ technologi not use the velocity on the keys. So, how strong / slow we press the keys, the sound level will remain the same.
At the Piano mode,modern keyboard using setting velocity. This also to imitate an acoustic piano, which, if we press the keys slowly, the sound level will be slow as well, and vice versa.
So, in your case,at the same volume slider, try to play on the organ modes, note level. Moving to the piano mode and press the keys securely powered (full power). Then the sound level should be equal to the organ mode.
On modern keyboards, also included organ sound that added velocity setting. Usually found on the user bank.

On organ mode, in general, almost all brands of the modern keyboard, velocity setting is not enabled. Setting velocity is used to determine how much the level of the sound that follows how strongly you press the keys. It is really just to imitate the sound of vintage organs, which in the past, electronic organ technologi not use the velocity on the keys. So, how strong / slow we press the keys, the sound level will remain the same.
At the Piano mode,modern keyboard using setting velocity. This also to imitate an acoustic piano, which, if we press the keys slowly, the sound level will be slow as well, and vice versa.
So, in your case,at the same volume slider, try to play on the organ modes, note level. Moving to the piano mode and press the keys securely powered (full power). Then the sound level should be equal to the organ mode.
On modern keyboards, also included organ sound that added velocity setting. Usually found on the user bank.

Possibly.
Depends what you mean by "off".
I know of an electric piano that sat in front of a window that leaked when it rained. Now the piano sounds like the vibrato is running at about 40 cps. It probably needs a new circuit board. But the owner doesn't notice it and he has no audience. "It sounds fine.", he tells me.
On the other hand, you may just have a lose part that physically vibrates inside somewhere when you play notes that resonate with it. It's hard to say without hearing it.

It sounds like there may be an issue with the piano sounds on your Kurzweil sp4-7 keyboard. One possibility is that there may be a problem with the software or firmware of the keyboard, in which case you may need to update the software or contact the manufacturer for assistance. Another possibility is that there may be a problem with the internal hardware of the keyboard, in which case you may need to have it repaired by a professional technician. In either case.

All I can suggest is try a master reset. It could be a software bug or a dried out electrolytic capacitor in the power supply.

Either the first or second closure matrix line for the "A" keys is bad.

This may be a cracked or shorted circuit board.

A bank of diodes is used to prevent sneak electrical path if more than one octave has notes pressed.

First thing is to clean ALL the key contact areas and the conductive rubber pills with 99% isoprophyl alcohol.

This involves dis-assembly of the key area. If you are not competent in electronics, best left to a pro shop.

The keys are scanned in a matrix, two contacts per key and all the individual notes are in common (all the "A;s", "B's"...) And each octave is strobed for the first set of contacts and then for the second set of contacts. an the whole octave is read in parallel.

The reason for two contacts is one closes first and then the other as a key is lowered. The time between these is measured and is the note VELOCITY which for a piano controls the loadness of the note. IF ONE of the two fail, the loudness will vary as yours does.

OK... It wasn't clear from the original.

Sometimes the keyboard has a mode that splits for upper and lower part of the keyboard, usually splitting at the F#/G. Also CERTAIN voices will ONLY sound one note at a time. Piano setting would not have this problem of course.

When you play a single note does that sound? If it doesn't in the fingered mode, then there may be a processor problem in the unit/

If it does, there is probably a problem in the matrix that scans the keyboard electrically. If one of the keys were ELECTRICALLY stuck on, the processor within could not read whole sections of the keyboard.

To troubleshoot the problem, press exactly one key at a time... do they all work for say a piano voice while in the fingered mode.

Next press a key at the high end of the keyboard and try others. See if you can find an octave that fails to work.

The problem is likely imbedded in the electronics and could be anything from a dirty key contact to a cracked circuit board. It is NOT likely you can fix this yourself unless you are experienced in electronics.

It's not really for the faint of heart, but generally this is caused by gunk getting into the key circutry. Underlying the 3000's keyboard is a silicone pad with 2 contacts on it, the measurement between each being hit is the issue usually but yours just sounds like there's something in there causing a physical or contact obstruction.

What you really want to do is to remove the keys and clean everything but this isn't easy... You could try using 99% alcohol (from a pharmacy) to clean inside it which may well help you.

There's a good thread on a similar issue at:

http://www.electronicspoint.com/roland-hp-3000s-digital-piano-dodgy-note-t18946.html

Which may help you work out how to do the disassembly if you are brave, but I would start with pouring some alcohol in and poking it and hoping for the best 1st. It sounds crude, but it works amazingly well with some things.