Sustain issue with Yamaha MM8

It sounds like you are having an issue with the sustain pedal for your Yamaha YPT-300 keyboard not working properly. There are a few things you can try to troubleshoot the problem:

1. Check the connection between the pedal and the keyboard to make sure that it is securely plugged in and not loose.
2. Check the settings on the keyboard to make sure that the sustain pedal is properly configured and enabled.
3. Try using a different sustain pedal to see if the problem is with the pedal itself or the keyboard.
4. Check the manual of your keyboard, some models have a specific setting to turn on/off the sustain pedal and make sure it's not turned off.
5. If the above steps do not resolve the issue, it's possible that there is a problem with the keyboard's internal connections or a malfunctioning component. In this case, you may need to contact Yamaha's customer service for further assistance or consider getting it repaired by a professional technician.

It's important to note that troubleshooting and repairing electronic equipment can be dangerous, especially if you're not familiar with the device, so it's best to contact a professional technician if you're not comfortable working with it.

I would suspect the sustain pedal jack on the keyboard is either dirty or defective. Try using some contact cleaner first, and if that doesn't work replace the jack.

To start with always best to use the correct power supply these should be readily available from any good Yamaha store. Is the sustain pedal a Yamaha pedal? The plug end of the pedal connect a multimeter across the two connectors and set meter to show continuity. If there is no continuity press pedal, hopefully this will now respond. If not then the break is in the pedal. If meter idea works then it could be the socket on the keyboard, these can work loose on the pcb they are mounted to if they are used a lot.

You could open up the keyboard and look inside checking the solder joints on the socket or simply take to a Yamaha service centre.

You could also try a master reset of the keyboard, hold down the highest note whilst turning on, this will reset to factory default.

Let me know how you get on.

Buy sustain pedal made for CASIO or switable model.
Pedal for Yamaha or Roland will work in reverse on a Casio.
If you cannot return for exchange, then open up and solder a different type of micro switch.

Since you didn't specify the model of the Yamaha I will take a good guess. MOST keyboards of all types default via their internal programming to use a pedal that is either a close circuit or open circuit switch. Basically it is two contacts from a wire that is connected (closed) or normally not connected (Open). When you press a pedal, the contacts either open or close. Your pedal has a switch that can choose either one. Now,.. the keyboard has some internal software that controls how the keyboard "sees" the pedal. It sounds to me that you have to get into the "control" section of the interface on the Yamaha and scroll to the "Pedal" polarity section. You might see it as a - (minus) or a + (plus) icon. See if you can make
one of them a default every time you power up. You see, every time you power up the keyboard, it is sensing something different. One last thought... or question...are you keeping the sustain pedal plugged in? or are you connecting and reconnecting it? The keyboard usually "remembers" or senses the polarity from the last power up. I have had similar issues with the Motif keyboards from Yamaha, but have remedied the issue by digging into the internal controls. Lastly, search the manual that came with your Yamaha. See if there is a section under Pedal or pedal polarity.

every sustain pedal got different polarity.. normally just go to global setting on your keyboard and change damper polarity setting to plus or minus (select which one work with your sustain padle).

This is confusing... you say "the sustain works when you disconnect the cord"? How can that happen? and doesn't work when it is plugged in.

MOST sustain pedal problems are due to people using a different pedal than the keyboard is designed to use. It is very common that someone tries to use a Roland sustain pedal on a Yamaha and oof course it doesn't work because the Roland pedal is normally closed and Yamaha usually requires a normally open contact.

A FEW keyboards now check the state of the pedal input when power is first turned on and configure the pedal polarity accordingly. For these keyboards, make sure the pedal is plugged in before power is turned on.

When push comes to shove, a factory reset never hurts.

Assuming you'd like to proceed with a factory reset, follow these steps:

This procedure makes it possible to restore the S08 to the original factory-installed Internal Voices, Multis and System settings.

WARNING: The current settings for all Multis and User Voices will be deleted. If the current settings and data are not expendable, create a backup before executing the Factory Reset.

1) Press the [UTILITY] button.

2) Press the [JOB] button. The 'FactorySet' screen will be displayed.

3) Press the [ENTER] button. The 'Sure?' message prompt will appear.

4) Press the [INC/YES] button to execute the Factory Reset. The 'Completed!' message will be displayed to indicate the procedure has been successfully executed.

5) Press the [EXIT] button to return to the Utility Mode.

What I figured out is that when i turn on the keyboard, if i hold down the pedal by accident, it will work in reverse. I dont know if this is what you mean. If it is, just dont touch the pedal when you turn it on. If it isn't, try to return the pedal. I dropped one, it had this problem, and they gave me a new one. Your cord for it might have been bent (?). Also, turn the keyboard on with the pedal already plugged in. It's not made to be plugged in while it's on. Hope this helps. - Matthew

I found that if I plug in the sustain pedal BEFORE turning the power on, it works fine. If I plug in the sustain pedal AFTER turning the power on, then it works in the opposite way. Probably just the design. So I would try playing with that before doing anything drastic.