Yamaha Electronic Piano- certain notes malfunctioning

If certain notes on your Technics SX-PR150 digital piano are playing at a lower volume than others, it's possible that there could be a few underlying reasons for this issue. Here are some steps you can take to troubleshoot and potentially resolve the problem:

1. Dust and Debris:
   • Check if there is any dust, debris, or foreign objects present around the keys and internal components. Dust or debris could affect the key's action and cause uneven volume levels.
2. Contact Cleaning:
   • If you're comfortable doing so, you can carefully open the piano and clean the contacts underneath the affected keys. Contacts that have accumulated dirt or oxidation might lead to volume inconsistencies. Use a clean, dry cloth or contact cleaner specifically designed for electronics.
3. Key Mechanism:
   • Inspect the key mechanism for any signs of physical damage, misalignment, or wear. Damaged or misaligned keys could lead to uneven volume levels.
4. Sensors and Sensors Board:
   • Digital pianos like the Technics SX-PR150 use sensors to detect key presses and control volume. If a sensor is malfunctioning or damaged, it could result in volume inconsistencies. Check the sensors and their connections for any issues.
5. Audio Output and Amplification:
   • Check if the issue is specific to the internal speakers or if it also occurs when using headphones or external amplification. If the issue is present across all audio outputs, it might be related to the piano's internal components.
6. Factory Reset:
   • Perform a factory reset on the piano to restore its settings to default. This can help rule out any software-related issues that might be affecting the volume levels.
7. Professional Inspection:
   • If the above steps do not resolve the issue, it's recommended to seek the assistance of a professional technician who is experienced in repairing digital pianos. They can diagnose the problem accurately and perform any necessary repairs.

Please exercise caution while performing any internal inspections or repairs on your digital piano, especially if you're not experienced in working with electronic equipment. If you're unsure or uncomfortable with the process, it's best to seek professional help to avoid causing further damage.

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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It's most likely to be dirty key contacts.
The contacts are conductive pads. They get "crud" on them over time, which then just needs to be cleaned in a certain manner.
Best to clean all the pads over the entire keyboard. It's not difficult for someone with experience, but it's not a job for a novice.
My guess is that the keys are toward the center of the keyboard.

It sounds like the piano is in mono setting. One note at a time can be played. Find out how to set it at poly mode, allowing multiple notes to be played at the same time.

There's an extremely comprehensive pair of videos about repairing this problem on YouTube thanks to David Allyn. I have embedded them below, or you can search "P70 Noisy Keyboard Repair".

First try looking in your transpose settings. Refer to your manual to see if any arpeggiation/unnatural chord settings were inadvertently created by you or made by another user. If you believe it is a software problem you can not solve, back up your memory bank, remove your memory card, and hard reset your keyboard. Insert your memory card and check to see if your problem still exists.
If it is a technical problem, it sounds like you may need to get it checked out by an engineer/repairman. Sometimes when a digital keboard's keys collect too much dust/debris they can trigger multiple keys that aren't being pressed. Think about it like a key getting caught on an upright piano and pulling back the hammer next to the one that was played. A digital piano works off of one or several printed circuit boards or PCBs. The printed circuits usually can not short circuit because the wires and circuits sit in fixed positions. If an alien conductive fiber or series of conductive fibers connects a conducter to another, or if there is any humidity inside your piano it may cause circuits to misfire when a circuit is connected in the area. This could explain why notes you are not playing are being activated in the area in which you are playing.

If you are in a humid area and you suspect that this may be the cause you can attempt to draw out the humidity before getting a an expensive diagnostic done. Find a box large enough to house your keyboard. [If it is on a stand take it off and] place it inside the box. Cover the keyboard with plastic wrap (so as to prevent any foreign objects from getting into the instrument) and very carefully surround the piano with white rice. Remove the plastic wrap, close the box and leave it alone for a few days. The rice draws out any moisture from the electronic components. Very carefully (again so as to avoid getting any rice inside it) remove the keyboard from the box; remove any dust from the body, face, keys, and other components. Try your keyboard now. If humidity/moisture on the PCBs was the problem it should be solved. If not it is time to take your piano for a tune-up.
Hope this helps!

Have a professional tune it for you. It may be that some strings have loosened/tightened.

I just experienced my p85 with a key problem on the F# below middle C. You will need to disassemble the keyboard and usually the keys are groups of 6 - 8 keys. If you remove the group that has the problem you might be able to find the problem visually. Mine just involved removing and reinserting the F# key back into the assembly. Then reinstalling the group of keys. If you can't get the key to work properly, you will probably need to buy the group assembly from Yamaha.

The keypads can develop dirt , failure of pads which can result in such malfunctioning. If you are able to open the piano then carefully remove the keypads , clean the surface and reset.
this must solve the issue unless the pads/springs/mechanism are having fault.

What has happened is that one of the contacts on those notes is not working properly. Each key has two contacts. One makes before the other as the key is pressed. The processor MEASURES the time between those as you hit the key to read the VELOCITY you have hit the key with. This velocity is often used for loudness on many voices such as the piano. These contacts are USUALLY conductive rubber pills suspended in silicone rubber "domes". One can disassemble the key area and clean BOTH the black rubber pills and the circuit traces they are pressed against using Q Tips and ONLY 99% isoprophyl alcohol to restore proper operation
One needs to be very careful when disassembling unit as there are many tender ribbon cables and connectors. Best to have clear work area and two people to "control" the halves of the shell while opening..