A/V "?": Noise from speakers when turning vol knob

[97tbird]

A/V guys,
I have a mini component Onkyo system which sounds great for its size. However, of late, I've been having this problem:
When I turn the (motorized, remote controllable) volume knob of the receiver past 9 o'clock position, I hear this faint "scratchy"/"staticky" noise from the speakers. I hear this noise ONLY WHILE THE VOLUME KNOB IS TURNING. it first began with only 1 spkr, but i think i hear it from both now...it stops asa the knob is still.

I pulled off the vol knob one day, and just put it back in, and the noise went away for a couple of days, but then came back.
all the spkr cable connections are firm and solid afaik.

The noise is pretty faint and happens only while turning the knob like I said, but it's annoying me.

should I pull the knob off again, and spray some electronic cleaner into the opening? (not really an opening, but I see some kind of metallic disc-like thingy...)..is it dangerous to do?
Thanks guys.

 

[97tbird]

just searched on the net...could it be this?:
"...However, potentiometers have their own unique problems. For one, they rely on physical contact between the "wiper" and the resistance strip, which means they suffer the effects of physical wear over time. As potentiometers wear, their proportional output versus shaft position becomes less and less certain. You might have already experienced this effect when adjusting the volume control on an old radio: when twisting the knob, you might hear "scratching" sounds coming out of the speakers. Those noises are the result of poor wiper contact in the volume control potentiometer...."

didn't say how to fix it though...
(someone told me to blow compressed air while turning the vol knob...didn't try that yet)

 

[Quattro Pete]

Guess what... I had the exact same problem:

http://www.avsforum.com/avs-vb/showthread.php?t=725002

However, I never actually got around to fixing it. I took it to a repair shop to have them take care of it under warranty, but they couldn't reproduce the problem/noise. Strangely, after I brought it back home, the noise was gone.

 

[BradC]

I've had this happen before on my Yamaha gear.

The volume knob should come off.

Blowing some compressed air into it may blow some dirt out, but what you need to do is spray some contact cleaner for electronics into it (should be able to get it at Radio Shack).

 

[97tbird]

Thanks BradC. funny you should say that. My brother who has a Yamaha amp also has the problem...(I don't know what he did)

Yeah the knob come off when I pull.
I have both compressed air and RadioShack contact cleaner...so spraying it into the opening won't harm it?
I guess I should wait until everything's dry before operating it, huh?

I read about a product called "DeoxIt" which should be even better than regular contact cleaner...wonder how this works:
http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=341-225

 

[sprintman]

Dirty pot. Geez that takes me back a decade or two. 20yrs as a techo before a lobotomy and a move to sales.

 

[CivicFan]

Ahh, volume control knobs. I thought the modern volume control knobs/slides had fixed this problem until I remembered that my 9 year old Panasonic home theater system does it, too. Fortunately, I don't use that POS any more.

 

[brianl703]

I use Caig Labs Deoxit D5 to clean dirty volume controls. It works better than anything else I've used.

 

[97tbird]

Quote:

---

Guess what... I had the exact same problem:

http://www.avsforum.com/avs-vb/showthread.php?t=725002

However, I never actually got around to fixing it. I took it to a repair shop to have them take care of it under warranty, but they couldn't reproduce the problem/noise. Strangely, after I brought it back home, the noise was gone.

---

yep; stereos are like cars

so Pete, did you try cleaning the volume knob/pot before taking it to the shop? didn't the cleaning work?

(for some strange reason I didn't see you post earlier.)

Thanks. the guy from your link suggested opening the receiver, which I really don't think I'm gonna do...too risky.
I doubt that there's a difference betw "electronics" cleaner and "control" cleaner...

 

[tom slick]

DeOxIt is miracle spray and exactly the fix for this type of problem. IT really does work well. you can buy it at radio shack.
a low tech cheap fix can also be to turn the knob back and forth rapidly 20-30 times. that will help to clean the inside of the pot.

 

[Quattro Pete]

The question is: is it enough to spray it from the outside or do you have to spray from the inside of the receiver?

Tbird, no, I did nothing since the guy in that post suggested opening up the receiver. Since the receiver was under warranty, I did not want to touch it myself. Instead I took it to the repair shop.

 

[oilyriser]

It's a circuit design flaw, or a leaking isolation capacitor, allowing DC to flow through the pot.

 

[Reg# 43897]

Quote:

---

Dirty pot. Geez that takes me back a decade or two. 20yrs as a techo before a lobotomy and a move to sales.

---

I remember being introduced to dirty pot. Nasty.

John.

 

[brianl703]

Quote:

---

The question is: is it enough to spray it from the outside

---

In my experience using Deoxit, it is almost always enough to spray it from the outside.

 

[97tbird]

when I pull the vol knob off, this is how it looks like behind it (pic below)
..I wonder what those 2 screws hold..i'm afraid if I loosen those, something will fall BEHIND that plate, which I won't be able to get to...I guess I should try to spray into whatever openings I see in there, huh?

The pic:

 

[oilyriser]

Those screws likely hold the pot in place. If you can find a replacement part, the system can be repaired.

 

[Papa Bear]

You will have to get to the back of the control. Spraying the front won't help. WD-40 will work great, just a spritz into the small hole on the back of the control.

 

[Papa Bear]

You shouldn't turn the volume knob past 9: o'clock anyway.

...

 

[97tbird]

PB: funny! actually I rarely go past 10:00 o'clock. the baby onkyo is pretty loud.
without doing anything i turned the knob back/forth several times fast while blowing compressed air into the holes...noise is gone...for now. gonna spray anyway the front..scared to open the thing.

 

[Quattro Pete]

haha.... my warranty is up in about 3 months - I'll open mine then if my noise reappears.