Yamana DGX 630 E keys make strange sound

SOURCE: No sound when piano keys are pushed on my Yamaha dgx-620

I'm sorry but it sounds like you will have to have it repaired professionally.

SOURCE: I have a Roland HP 101 digital piano however certain dont sound

White spirit is NOT what you should use. Mineral spirit leaves a residue film.

Use 99% isoprophyl alcohol.

ALSO inspect the contactboard for cracks by candeling with bright light behind it.

Testimonial: "bur isnt it strange that certain keys have stopped working? ie most the A keys"

SOURCE: Yamaha Electronic Piano- certain notes malfunctioning

Either the first or second closure matrix line for the "A" keys is bad.

This may be a cracked or shorted circuit board.

A bank of diodes is used to prevent sneak electrical path if more than one octave has notes pressed.

First thing is to clean ALL the key contact areas and the conductive rubber pills with 99% isoprophyl alcohol.

This involves dis-assembly of the key area. If you are not competent in electronics, best left to a pro shop.

The keys are scanned in a matrix, two contacts per key and all the individual notes are in common (all the "A;s", "B's"...) And each octave is strobed for the first set of contacts and then for the second set of contacts. an the whole octave is read in parallel.

The reason for two contacts is one closes first and then the other as a key is lowered. The time between these is measured and is the note VELOCITY which for a piano controls the loadness of the note. IF ONE of the two fail, the loudness will vary as yours does.

Bill Coan

• 49 Answers
• Posted on Oct 31, 2010

SOURCE: the keys in the middle

Although the keys have a weighted feel, this is not because of a system involving connection t hammers as in an acoustic piano. This is done mechanically, however, which would indicate a need for cleaning. If you have an authorized Yamaha service center in you area they would need to do the cleaning.

SOURCE: I'm using the Yamaha P-85

In playing fast you have to make sure to release the note fully and let the key come up. These keys have TWO contacts that are used in the scheme to measure note velocity. If BOTH contacts don't open, the note will NOT re-fire. The second symptom you have written would be a characteristic if one of the disconnect diodes has shorted. These diodes direct the strobe signals that scan the matrix of key contacts to avoid other octaves responding when multiple keys are depressed including those in other octaves. Servicing of the unit is required. It is unlikely you have the tools to DIY this problem. ONE THING to try is to tip the unit and gently tap it to see if some debris MIGHT have fallen in that may be shorting some of the matrix connections.