Humming Sound In Yamaha PSR e403 Keyboard

By on January 23, 2015
yamaha keyboard repairing









yamaha keyboard repair

My nephew called me to check on his Yamaha Keyboard with the problem of humming sound. On testing I observed the humming sound coming from both the speakers and it kept  gradually increasing. Hence we opened the keyboard for inspection.

yamaha keyboard repairs

This type of Humming sound problem are most likely due to either earthing problem or due to some faulty capacitors hence I decide to directly check the amplifier section.

On visualize inspection everything looks ok. I have removed the PCB; there are very few components on this section.

yamaha keyboard repaired

So I have downloaded IC data from the internet for reference for IC BA 5417 and I have decided to test the capacitors which are directly grounded from IC (Because I am getting Humming from both the speakers if you get humming from only one speaker then test respected output pins i.e. pin number 2-3 and 5-6) so I have started with big capacitor which is connected to pin no 4 and 8 which is supply voltage to IC.


I found the 1000uf 25 volt e-cap bad and this is the reason why it causes the humming sound.

yamaha keyboardrepairing

After replacing the capacitor I powered “ON” the Keyboard and tested it for ½ an hour. The humming sound was gone. My nephew was so happy and I can’t describe in words about his expression.

This article was prepared for you by Yogesh Panchal who works as a Computer Hardware Engineer in Mumbai India.

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  1. Waleed Rishmawi

    January 23, 2015 at 9:49 am

    capacitors usually the cause for such humming. a job well done on the repair. keep up the good work

  2. joe

    January 23, 2015 at 10:37 am

    Wish we could see if the top of that cap was bloated... Cap failed ESR?

  3. Robert Calk

    January 23, 2015 at 11:38 am

    Good job Yogesh. Thanks for the article.

  4. Mohamed Sittiq M

    January 23, 2015 at 11:54 am

    Thanks for your information for sharing..
    Mohamed Sittiq M

  5. Mark

    January 23, 2015 at 3:48 pm

    Well done Yogesh.
    Did you test the caps for high ESR? Is that how you found the fault?

  6. Chridtopher Babu Reddy

    January 23, 2015 at 4:10 pm

    good job done thank you keep it up

  7. Lyudmil Barosov

    January 23, 2015 at 5:38 pm

    Hello.Thanaks a lot for information.
    Some times are used capacitors with undervoltage needed.And when appear signal it is added or substracted from that voltage,and the capacitor maybe damaged.For example if the capacitor is for 20 volt and we give it 22 volt sinusoidal
    on the positive picks the voltage will be 31volt and on the negative part of the sisus
    signal the voltage across the capacitor will be
    9 volt,so the positive picks can damage the
    capacitor.By the way the oscilloscope is repaired.Mr Yong you were right.The problem
    was in the horizontal part of the schematic.
    One transistor was shorted-between C-E.KC509

  8. Mike Zook

    January 23, 2015 at 7:57 pm

    Good job Yogesh, Keep up the good work. Thanks for the post.

  9. Sethu ramachandran

    January 23, 2015 at 9:43 pm

    good job done yogesh.. . your Repair article should boost the service partners to migrate to repair all types of Electronic products

    Thanks and good luck to u.

  10. Humberto

    January 24, 2015 at 12:25 am

    Hi Yogesh Panchal, this e-cap causes a lot of hum that goes out for the speakers, its ESR value must be high. Anyway congratulations for your repair.

  11. Yogesh Panchal

    January 24, 2015 at 1:09 pm

    Thanks everybody for your comments.
    I don’t have ESR meter or capacitance meter yet; I just took a chance because most of time I have directly replaced the capacitors which are directly grounded from IC voltage supply Pin in audio system with Humming problem and capacitors also not that much expensive. Infect I keep some capacitors spare with me for testing purpose also i.e.

    1000uf 25V
    470uf 25V
    220uf 10V
    47uf 16V
    100uf 16V
    10uf 50V


    • living

      November 19, 2016 at 6:24 pm

      After changing th d 1000 uf 25v capacitor Im still getting the buzzy noise

    • Prashant Patil

      March 12, 2017 at 7:38 am

      Hiiii sir , i am having problem of huming in 1 speaker of my psr e 203 wind redio type huming coming from 1 speaker any solution for that

  12. Ed

    January 26, 2015 at 7:40 am

    Keep up the good work

  13. Tito

    January 26, 2015 at 9:22 pm

    Good article Yogesh. Capacitors are a problem nowadays sometimes if not bloated they just leak.

  14. Joshua Oloo

    January 29, 2015 at 12:36 am

    Thanks Mr. Yogesh for the article.keep the fire burning.Cheers.

  15. Albert Hoekman

    February 2, 2015 at 6:43 pm

    Nice job and explanation, thanks.

  16. Nitram Mosay

    February 3, 2015 at 11:50 pm

    Hi Mr Yogesh Panchal,

    Thank you very much for sharing your information with us,nice article.

    Best regards

    Nitram Mosay PNG

  17. peter

    February 10, 2015 at 5:34 am

    Experience has directed you to a suspect capacitor on the supply board.
    Quick low cost replacement probably quicker than testing & it worked.
    Good instincts but I think you should buy an ESR meter which will sooner or later help your repair work.


    July 13, 2015 at 12:34 pm


  19. Venu shankar

    February 19, 2018 at 7:13 pm

    I have a problem with my PSR 403 keyboard
    When I press any key and getting two notes tone ( exp: press C and getting C and F# , same like all the keys )
    Plz anyone tell me what is the issue and how to solve

  20. Opeyemi Daniel

    March 2, 2018 at 12:31 am

    My yamaha keyboard has the same issue but i tried changing the 1000uf 25v capacitor but it still has the same issues..
    i do not know much about testing capacitors. any help?
    Also whatever help i can get


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