Yamaha ypp-55 digital piano issue...

[bigdaddy234]

Hey guys, picked up a ypp-55 that was dropped i think....when its turned on it makes a cracking noise from the speakers and when you play notes you can hear them come threw the cracking sound....... any idea what this could be? i opend the piano and eveything looks fine ..nothing unplugged etc..... im assuming its the main board seeing how it still turns on etc...... has anyone ever heat treated these boards with a heat gun etc?

any suggestions would be great , thanks.

 

[The Y_man]

Does the crackling come thru headphones? Also, does it crackle while moving the volume control without anything playing?

The Y-man

 

[DickR]

Yes that's a first thing to check as the Y-Man suggested. If the sound is ok trough headphones you have to look at the speakers. If a 'coil' is damaged or bend by the drop, they give a crackling noise if they work at all. Also you can try LINE-OUT on a pair of external powered speakers or home-stereo.
Heat treating??? Only if you want to take the paint off

 

[bigdaddy234]

thanks for the replys guys.... I will check to see if the sound comes threw the headphones.......i should mention that it mostly just crackles ...very seldom will you hear notes as DickR said........ what do the coils look like?.... it sounds more like a bent or damaged coil to me......

 

[DickR]

Basically 'coils' are 'spools' at the end of the paper or plastic speaker-conus. You can not see them unless you open the speaker.
They have to move in free air (but very close to it) around a strong magnet and move, if they get a signal, quickly up and down and so move the 'conus' and produce sound.
If for any reason the coil is bend or more or less blocked by dirt or whatever, they can't move free anymore. The result is..... guess, yes.... a crackling noise.
If you have the keyboard open press VERY CAREFULLY the conus op and down a tiny bit. If you feel any 'gritty' or even hear a 'scraping' sound. The speaker needs to be replaced.
I need a coffee now.
Hope you find it, let us know.

 

[bigdaddy234]

Hey guys, so after further testing...... when you first fire the piano up it just hisses threw the speakers........or headphones, doesent matter...... then after 5-10 min the hissing stops and then it will be completely silent....then randomly it will play the demo (i leave it in demo mode) but it sounds very crackly and only plays it for a second or two then it will go back to being silent. Once when it started playing the demo i quickly took it out of demo mode and played some notes on the keys and they were working....then it cut out again and went silent.... the speakers are working fine and so are the keys and all of the buttons and volume control also work.......it really sounds like a main board issue to me......can they be fixed?

 

[The Y_man]

Sounds like pre-amp on last legs.....

The Y-man

 

[bigdaddy234]

so what part do I need? or can it be fixed? im good at soldering

 

[The Y_man]

It's likely a cracked solder joint (if it was dropped) - hence the behaviour change as the temp on the board changes.

You might be able to find it if you remove the board and use an inspection magnifying glass/light - but they can be hard to see.

The only other way is to test the joints, but you need a circuit diagram and relevant test points.....

The Y-man

 

[bigdaddy234]

what about heating the underside of the board with a heat gun remelting all the solder joints?

 

[DickR]

HEAT GUN??? Oh oh, that is drastic!! Doing that, and if the problem is not in a soldering, for sure you create bad solderings or melt components unless maybe if you have prof equipment and skills.
Advice: take the keyboard to a qualified repair person, With a scope attached they can tell you quickly what the problem is.