Kurzweil SP76 piano - loud A-flat

[bass_dinger]

I have a Kurzweil SP76 piano.  It is touch-sensitive (or rather, velocity sensitive).  The harder I hit the key, the louder it is.

 

However, since this morning, the A-flat below middle C is always at maximum volume.  Any ideas on what the problem might be, and how to fix it?

[BassTractor]

On 10/05/2025 at 12:23, bass_dinger said:

I have a Kurzweil SP76 piano.  It is touch-sensitive (or rather, velocity sensitive).  The harder I hit the key, the louder it is.

 

However, since this morning, the A-flat below middle C is always at maximum volume.  Any ideas on what the problem might be, and how to fix it?

Now I don't know the Kurzweils specifically, but it probably has a type of hammer and a sensitive pad underneath (I don't know the right terminology here).
This pad then probably is knackered - - not necessarily after impact: tmight be dirt or corrosion or whatnot - - and in case needs a repair or replacement. You could try opening it. As said, I don't know the specifics of these.

Me, I'd open the piano and, if all of the pads are identical, I'd simply use the pad for a non-used key on the dusty end, moving it to the position in question.

You might also be able to get a new pad from the importer. However, I tried similar for my Roland, without success for half a year, so this might be trickier done than said.

Best of luck whatever way you choose!
bert

 

 

Edited May 11, 2025 by BassTractor

[bass_dinger]

Thank you, @BassTractor. Other Internet searches suggested the same issue, so I need to pluck up the courage to take the piano apart, and look at the pad beneath the A-flat.

 

More likely, I will contact a repairer that I know, and ask him to look at it - I am not a bold or confident fixer of things. 

[bass_dinger]

On 10/05/2025 at 13:05, BassTractor said:

might be dirt or corrosion or whatnot

 

It could indeed be dirt.  This video suggested that I can take the keyboard apart, and clean it.  However, I am not sure that I have the courage to try it, yet.  

 

 

 

[bass_dinger]

I took the Kurzweil apart and managed to clean the contact pads, and the keyboard now works again.   Thanks to @BassTractor who encouraged me to have a go!

 

I needed to take out the G and A keys to get at the A flat key, but once they were removed, the rubber contact pads were exposed, and a liberal squirt of contact cleaner got underneath the rubber contact pad and removed the dirt.  I didn't even need to remove the rubber contact pads to access and clean the contact points underneath. 

 

 

Rubber contact pads are shown here    

As far as I can make out, the velocity of the note is worked out by timing the difference between the first and second signal from the first and second contact points. I am guessing that one of the contact points was dirty and so the system only registered one signal, which it assumed was infinitely fast (and so, the maximum loudness).

 

The video here gave the details of what screws I needed to remove to get into the casing, and what to clean once I was in.

 

 

 

[BassTractor]

4 minutes ago, bass_dinger said:

I took the Kurzweil apart and managed to clean the contact pads

 

Success! Congrats on this.
Very satisfying, innit, to have done it yourself and to have succeeded? You're also better than me: my Roland still stands unrepaired.

all the best,
bert

[Hellzero]

Been doing this so many times during the 90's and early 2000's when I had my own repair shop... But I always removed the rubber strip to make a full cleaning as these were still the cigarettes glory days and most of these keyboards were simply full of smoke residues and soooo sticky. 🤢🥴