Left speaker crackles on volume adjustment PSR-530

[JEkema]

Hello All,
Hoping I can get some help here...

I have a Yamaha PSR-530, and when first powering on, the first few turns of the volume knob result in some extremely loud crackling noises coming from the left speaker. After a few turns, it starts to settle down into an annoying (but not earsplitting) crackling.
It does not matter what the volume is originally at, it always crackles loudly at first, then quiets down a bit.

After doing some research, I've found that a dirty/dusty volume control can be the cause of this. Recommended solutions include spraying contact cleaner into the volume control, or turning the volume up and down rapidly about 20 times. I took the keyboard apart, and the volume control did indeed look dirty. I tried compressed air, but the dust was stuck pretty well. Not having contact cleaner, I took a clorox wipe to it and cleaned it up as best as I could. Then I turned the volume up and down 30-40 times, and plugged it back it, but it didn't seem to make a difference...

I also took a look at the left speaker, and blew it off with compressed air, but didn't seem to help. The speaker sounds perfectly fine when not adjusting the volume, so I'm thinking it's something else.


Has anyone had experience with this, or have any other suggestions? It's a nice older keyboard, and plays great. However, I'm not going to dump a bunch of money into it, but if it's something I can do myself, I'm all ears...

Thanks in advance!
James

 

[JEkema]

I looked at a few other posts on here... I don't know why I didn't think of this right away, but I threw a pair of headphones on the keyboard...

And the crackling does come through the headphones as well... Which tells me that it is definitely not the speakers...

Does this help any? I would really like to find out what is causing this...

 

[happyrat1]

You were on the right track with the dirty pot diagnosis. However, using Clorox to clean it probably did more harm than good.

A spray can of contact cleaner costs less than 10 bucks at any Radio Shack. Run like the dickens to the closest one on the 26th and pray you haven't destroyed your pot with hydrochloric acid, which is essentially what Clorox is.

Happy Holidays,
Gary

 

[happyrat1]

Here's a video on how to properly clean a dirty, noisy potentiometer.

 

[happyrat1]

Here's the ingredients list for clorox wipes.

http://www.clorox.com/products/clorox-disinfecting-wipes/ingredients-and-safety/

Read the MSDS data sheets for the particular flavor you used. There's some nasty, corrosive ingredients in there.

 

[b3maniac]

There seem to be a lot of people who aren't familiar with basic electronic methodologies. I always keep some contact cleaner in the tool box.

 

[happyrat1]

Agreed. A little goes a long way. I bought a can of the stuff almost twenty years ago and it's still mostly full. Use it sparingly and a can will depressurize long before you use it up.

 

[JEkema]

Hey Gary,

Thanks for the reply! I hope I didn't ruin anything with the Clorox wipe, for what it's worth, I only wiped off the outside of the metal basically... but sounds like either way it was a dumb move... I did read the container a little, and it said to "unplug small electric appliances before use", so I figured it would be OK... but yeah, I'm definitely no electrician...

And thanks for the video, that was actually the one I watched that made me realize it might not be a speaker problem...

I am a little concerned because the volume control on my keyboard doesn't look a whole lot like the "pot" in the video... it's a little late tonight to take it all back apart, but tomorrow or the 26th I will try to post up a picture of it... And I will have to make a run for some contact cleaner...

If I can ask one more thing, it still seems a little weird to me that a "gunked up" volume control would make just ONE speaker act up... Why wouldn't it effect both? They're not wired separately through the volume control, are they?

Thanks again for the help. I appreciate it!

James

You were on the right track with the dirty pot diagnosis. However, using Clorox to clean it probably did more harm than good.

A spray can of contact cleaner costs less than 10 bucks at any Radio Shack. Run like the dickens to the closest one on the 26th and pray you haven't destroyed your pot with hydrochloric acid, which is essentially what Clorox is.

Happy Holidays,
Gary

 

[happyrat1]

Hi James.

Potentiometers come in many types and configurations and flavors.

A stereo pot is usually a pair of potentiometers layered on top of one another and controlled by a single control shaft or slider.

Here's a few pics of what I'm talking about.

How they work is that there's a small carbon plate or wirewound torus acting as a resistor and when you turn the knob, it moves a conductive phosphor bronze wiper across it in an arc. the three terminals for each pot are the two ends of the resistor and the direct wire to the sliding contact.

How you wire it up in the circuit determines its resistance value in the range of the pot.

Anyway, contact cleaner is safe for the phosphor bronze wiper and the resistive material and also lubricates the switch or pot while it cleans. Like the video demonstrated, you have to open up the casing and squirt the stuff directly inside the pot using the thin straw that comes with the can. Usually there are a few access holes handy for just that purpose.

No other household product is an effective product and would probably damage the component.

Also you should squirt a little into the front panel bushing where the shaft enters the control on the panel side. Just remove the knob and use the same technique. Two or three short squirts on both sides should do the trick. Work the shaft back and forth about a dozen times while you spray.

At any rate to answer your question about why only one channel was affected, the two pots ganged into a stereo control don't necessarily age or deteriorate at the same rate and since they are electrically isolated in the circuit, any flaws in one would not affect the other's circuit.

Anyway, give the pot a good squirt with the contact cleaner and wipe down the housing afterward and hopefully it will remove the residue left behind by the clorox wipe as well.

Merry Xmas!

Gary

 

[JEkema]

Hi Gary,

Merry Christmas to you and all as well!

Sorry I did not get back yesterday, some moron from Charter thought it was a good idea to mess with our box, and knocked out our internet for the night...

Anyway, what you suggested worked like a CHARM!!! I thank you all so much for the help and the explanations and images, it is very greatly appreciated!

Below is what my volume "pot" looked like... to me, it looks too thin to have two "pots" stacked on top of each other, but apparently that's what it is? Anyways, I grabbed some contact cleaner, gave a few good squirts in the little hole, and could feel the knob loosen up immediately...





With the clorox wipe, I simply wiped off the outside of the metal... looking back, I'm not quite sure what I thought I was accomplishing, but I'm just glad I didn't try to go any further with clorox, as I probably would have done some damage...

Well, I put the keyboard back together, and the volume changing is quite as a churchmouse now... no more crackling... and I LOVE it! It's like having a brand new keyboard!!!

Thanks all again SO MUCH for your help, it's amazing how far you can get with just a little "know-how"...

 

[happyrat1]

Yeah that's a layered stereo pot alrighty. The 6 terminals give it away and the 7th pin is probably a chassis ground.

Anyway, I'm happy it worked our for ya and I hope Santa was good to you

Regards,

Gary