To CVP 509 owners

[JohnDiV]

To all who own CVP 509PE and maybe the 500 series not sure about that.

There is an issue with the amp inside. I have a slight humming sound from the speakers below. Does not depend on volume. They are sending a repair guy out to cut a trace on the board to separate the DC an AC ground. It is not a loud hum at all and you only hear it when your head is under the piano, however it is there and it is 60 cycle hum. Just a heads up for the 509 owners. I am not sure what serial numbers are affected, or I am just the lucky one, but this unit was made on 1-19-2010. Really recent.

[JohnDiV]

Just wanted to let everyone know that the hum that I had written a post about was fixed today. Yamaha's fix to cut a trace on the board to seperated the DC and AC grounds and it worked like a charm. No more slight hum.

Again this was a low level of noise but it was a 60 cycle hum and not a broad sprecturm of noise (hiss) which is nomal to have a little of when you put your ear about 2" to 6" near a speaker or on the speaer grill(s).

[Gwenlyn Norton]

Thanks so much for the information, John. We just purchased the 509 and do not hear any hum. We must be one of the lucky ones. We will certainly keep our 'ears peeled,' however.

[Nikki]

My CVP-509 does appear to have this hum. I can't hear it when I sit to play. If it's only audible when I have my ear inches from the speakers then it may not bother me. Who knows, I may want to sell it in a year or two and the buyer may want to know if this fault has been fixed. In this case I may want to have it fixed. There was a YouTube video demonstrating this fault, but it appears to have been removed. Is there any situation, apart from when one's ear is close to the speakers, where this hum is an issue?

How much do the engineers have to dissect to get to the PCB?

Nikki

[JohnDiV]

Hi Nikki,

No the only issue was the hum.

[Nikki]

Originally Posted by JohnDiV

Hi Nikki,
I would get it fixed if I were you while the are hot to fix it.

OK, I'll definitely get it fixed. I have an aquarium running a pump just a metre away that emits a 50hz hum so it's masked a little.

Nikki

[bigaxl]

Originally Posted by Nikki

There was a YouTube video demonstrating this fault, but it appears to have been removed. Nikki

This video was uploaded by myself. I removed it, cause here ist a deal with Yamaha Europe. This week my CVP-509 will be changed to a complete new one. I will report...

[Nikki]

Originally Posted by bigaxl

This video was uploaded by myself. I removed it, cause here ist a deal with Yamaha Europe. This week my CVP-509 will be changed to a complete new one. I will report...

Small world. Do you mean "it's a deal"? A new one? You've got my attention now. I will await your report..

[bigaxl]

Originally Posted by Nikki

A new one?

Yes. I own my CVP since last 15.12.2009. I told my dealer/Yamaha, that I don´t tolerate any repair or experiments. No betatesting here!

[RBmusic]

Without knowing the SPECIFIC circuit board I am of the opinion that cutting etch is a hack and tacky way of fixing ground hum.

How & why anyone got to connect a/c ground to the amp (audio section) ground on the same board is just weird.
IMO it represents a DESIGN PROCESS problem, I can't see cutting etch at a place where it just happens to be convenient to do so, as any kind of a solution, just a hack.

No design rules at that place ?
I guess not (-:

[JohnDiV]

The connection of the AC and DC ground
Just my thoughts. PS no hum or hiss anymore.

[Nikki]

Originally Posted by JohnDiV

Not an experiment, a valid fix.

Thanks for allaying my fears. Was starting to get worried. You should know, you build nuclear power plants FGS!

Originally Posted by JohnDiV

Sometimes when you get an exchanged you get another problem like keys not lined up, or led not working. You just did not notice it yet.

Like exchanging an LCD TV with one dead pixel for one with 10? It's a lottery.

Keys not lined up? One key is marginally higher than the rest on my CVP-509. It's tolerable.

Nikki

[JohnDiV]

Hi Nikki, it is normal to have keys slightly higher than others.

[RBmusic]

Originally Posted by JohnDiV

The connection of the AC and DC ground was on the regulator board not the amp. And they do it all the time . At some point the AC and DC grounds have to connect. However in this case they connected it once to many times on the Regulator board. The AC and DC ground is still connected on the board, has to be. But not were that added a trace to ground. Just a ground loop. Not an experiment, a valid fix. Also the hum was very low, I listened to other manufacturer and their Speakers had hum/hiss louder then the problem Yamaha had. Sometimes when you get an exchanged you get another problem like keys not lined up, or led not working. You just did not notice it yet.

Just my thoughts. PS no hum or hiss anymore.

The process problems are;
a) That it shouldn't have been possible BY DESIGN to connect grounds in more than one place. To me this indicates a lack of design discipline.
b) That it got to the customer level. This is more than a lack of serious bench testing.
Even with SIMPLE bench testing it would be a part of a normal test protocol to scope various points for ground ripple.
It shouldn't have to be HEARD, it can be measured.

Again, I m not familiar with the details of this board, but it is my understanding that it is essentially the same as the 40x, 30x series and perhaps a generation before that.
More and different voices, different signal processing, etc., but almost certainly the same board layout.
So how long has this "legacy" problem been in clavs ? and how did the tech just have it at his fingertips as THE instant fix ?

[dbjorck]

Hi!

Originally Posted by RBmusic

Again, I m not familiar with the details of this board, but it is my understanding that it is essentially the same as the 40x, 30x series and perhaps a generation before that.
More and different voices, different signal processing, etc., but almost certainly the same board layout.
So how long has this "legacy" problem been in clavs ? and how did the tech just have it at his fingertips as THE instant fix ?

I remember this problem being mentioned on a 2xx years ago.

Yamaha is simply no longer the quality product it is supposed to be. And they are resting on their laurels riding the wave of previous reputation. And that upsets me.

It is still mostly a very good instrument though. Although I have two broken buttons, and now 5 broken keys - problems which started just after the warranty ran out, and which according to the salesman will be more expensive to fix than buying a new piano. I am not a happy customer. It is more and more becoming "Casio".

Brgds

Danny