Repair and disassembly guides for electronic keyboards.

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Intermittently no sound made


I have a Yamaha PSR 400. The keyboard is intermittently loosing sound, i.e. every 4 or 5 keys then no sound. It's not any particular keys.

Not sure what it would take to fix this or if it's even worth it?


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Hi @jubilee,

Presumably you mean that after playing the keys the sound stops. Is this correct?

What do you do to make it play again?

There may be a loose cable connection between the keyboard circuits and the mainboard and the vibrations caused by playing may cause it to disconnect.

Alternatively, is the power disconnecting from the keyboard (no lights etc) when you do this?

In any event the keyboard will have to be opened and the problem investigated.

Here is a link to the service manual for your keyboard player. It details the steps to dismantle the keyboard and has all the relevant information you need to diagnose the problem

To download the manual when the sentence below the Document preview box changes from This file is downloadable free of charge: ...processing... to This file is downloadable free of charge: Get Manual, click on the Get Manual as this is the download link. Be patient, it takes a little while to find the file.

Hopefully this is of some help.

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Hi, Let me better explain what it sounds like. After every few keys the sound either seems to be lost for a split second/half a second (no sound), sometimes it's actually so quiet I can hardly hear, then other times it gets super louder than the other keys. If I stop playing, then everything goes back to normal until the 4th or 5th key (not location on the keyboard, but the 4th or 5th key in any song or pattern that is played) is played again. The keyboard display and lights never go out.

I was able to download the manual and that helped me to open the keyboard. I tried to vacuum out some of the dust. But I don't know where else to start to troubleshoot this. I tried to start the TEST Program 1 but when I turned the power on, it shut down right away. TEST Program 2 will keep the power but it just says P500 in the display. Not sure what that means. I then tried toggling back and forth between starting TEST Program 1 and 2 and at some point I get ER2 error message.

Any thoughts as to what is the issue?



My reading of the manual indicates that Tests 1 and 2 are the same except that Test 2 doesn't do the first 5 tests (p.19 Program tests 3-7 in the manual). I don't know why Test one behaves as you describe.

I'm wondering if the P500 display message you are getting in the display is actually what is meant for Step 8.

How long does it take to show the P500 after you initiate the Test 2 program?

If it is immediately then obviously it is not doing any tests. If it takes a little while then perhaps it's doing the tests and there are no errors to show up to that point in the test..

Have you tried pressing the "Voice Select +" button to see if the test advances and then continuing on as per the manual?

It is interesting what you said regarding the volume levels. I'm wondering if the volume control pot is playing up. What level have you got the volume at?

Try holding a note and moving the volume control up and down and listen if the volume moves smoothly with the changes or skips and jumps between level where it is at (depending on where it is) and loud



Something else looks like it is about to come up before the P500 comes up but it is so quick I am not able to read it. It looks like it may be an ER or CLR or something like that.

Hitting the '+' sign under the Voice Select area doesn't do anything other than to make a sound (that is if I am hitting the correct button) during the testing. Hitting other buttons makes different sounds.

Volume works perfectly fine it that it gets louder and softer as expected when holding a key and sliding it up and down. Even if I have the volume down really low, the same issue happens.

What is memory backup and why could I be getting Er2?




Not sure what memory backup is but perhaps it is where your "recorded" music may be stored.

If the memory is faulty or corrupted this might be affecting things.

Not sure about your keyboard but I suggest you try a power reset and then a factory reset and see if this alters anything.

If it does work you will lose any stored music that you have created. Any music that is provided by the keyboard and stored for you to play along with is retained. Just that you are aware.

First turn off the keyboard and then turn off and remove the power adapter from the keyboard. Also remove any batteries that may be in the keyboard.

Then switch on the keyboard for about 30 seconds. This will dissipate any residual power left in the keyboard and hopefully reset any setting or data that may be locked up.

Then switch off the keyboard and plug in the power.

Press and hold the far right white key on the keyboard and switch on the keyboard.

This will restore the keyboard to its' factory default settings.

Release the key and then turn off the keyboard.

Switch on the keyboard and then before doing any tests as per the service manual play some music to check if the problem is still there.

If not try the tests as per the manual and check if they now work.



I tried the reset and it didn't correct the issue. Not sure how to proceed from here. I think I'm going to have to give it up. Hopefully I can find someone out there who can fix this and make use of it, or else unfortunately it will have to go to e-waste :(

Thanks for all your suggestions and efforts.


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