"Knob switch" Wont Click On Or Off

Mr Antt · #1 05-10-2011, 04:08 PM

Hi there, I'm not exactly sure how to word this. And I'm sure I'm not the only person this has happened to, but... On my amplifier there's no On/Off switch. Only a control knob labeled 'Master' which to turn the amp on and off must be twisted until it clicks. And the same to turn off, in reverse of course.

Basically, the problem I'm having is I cannot click it on or off. I can turn the knob until it is stopped, indicating maximum volume. And the same for minimum volume. But, if I try to click the knob off the knob itself just spins on the pot underneath. It's at the point where it should click, it just wont.

Any ideas what may be wrong? Any help at all would be so greatly appreciated.

Thanks, Anthony.

fdeck · #2 05-10-2011, 04:42 PM

Does the knob have a set screw? It may simply be that the knob is so loose, that it spins rather than overcoming the force necessary to click the switch.

If not, those kinds of pots are available and can be replaced. What kind of amp?

Mr Antt · #3 05-10-2011, 04:53 PM

It's a Titan TA/50A head. I got it on eBay for £30, and it worked fine just suddenly doesn't. I know nothing about this head, never seen or heard of Titan before. But I saw the price, and how close the seller lived and jumped at the oppurtunity. I have a picture if you wish to see it.

Sorry if any of that's irrelevant. I'll open it up and see what I can find like you suggested.

Thanks, Anthony.

fdeck · #4 05-10-2011, 04:55 PM

I would suggest tightening the set screw on the knob first. Another possibility is that the entire pot has worked loose.

Mr Antt · #5 05-10-2011, 04:58 PM

I'm looking at the pot as we speak. I see now screw, would a picture of the pot be useful?

My name is Mudd · #6 05-10-2011, 05:05 PM

Is the screw set into the knob itself?

fdeck · #7 05-10-2011, 05:10 PM

There are also knobs that press onto a knurled or splined shaft. The splines can wear out.

Mr Antt · #8 05-10-2011, 05:12 PM

The actual control knob is detachable, and underneath is a white plastic stick. The bit that twists, I know nothing of technical terms. Then there's a really thin bolt, do I need to tighten that maybe?

If that's the solution I'm going to feel so incredibly stupid.. I just tend not to think properly sometimes.

My name is Mudd · #9 05-10-2011, 05:14 PM

Yes, try carefully snugging the bolt, which is most likely actually a nut, down while (trying to) not let the pot itself rotate.

Mr Antt · #10 05-10-2011, 05:30 PM

I've tried tightening the nut (Of course, not a small bolt...) and still there's no difference.

Sorry if I'm making this harder than it needs to be.

My name is Mudd · #11 05-10-2011, 05:32 PM

Pics would be good about now, if possible.

Mr Antt · #12 05-10-2011, 05:41 PM

I'm terribly sorry for I am unable to supply you with images tonight as the USB cable for me camera has taken itself for a walk. The one time I need things in my home to be in their places they're not.

However, thankyou for all your help so far.

Hopefully this can be picked up soon.

Thanks again, Anthony.

My name is Mudd · #13 05-10-2011, 05:57 PM

No worries...that's one reason we're all here, and a belated welcome here also.

Out of curiosity, where are you ?

Mr Antt · #14 05-10-2011, 06:54 PM

I'm here in the UK, in the East Midlands. Currently 1:53 AM here.

And thankyou for the welcome and the help. It's nice to know there are people out there with the decency to help those in need.

billfitzmaurice · #15 05-10-2011, 08:10 PM

There are volume pots that have switches added to the rear of their housing, and they can break. They're usually found on radios. It's easy to have a techie install an actual power switch.

My name is Mudd · #16 05-10-2011, 11:24 PM

I was wondering if the switch had broken also, especially after reading about the plastic bit.

Mr Antt · #17 05-11-2011, 02:53 PM

Alright, I've got a couple of pictures. The quality isn't amazing, but I think it's clear enough to see.

I hope they're okay for you.

Thanks, Anthony.

My name is Mudd · #18 05-11-2011, 06:56 PM

Good enough.

So...you've tightened that brass nut down snug; the pot itself doesn't rotate in the case; the volume does go up/down correctly; but it won't turn on/off? If so, my (completely unscientific) opinion is the the switch part that Bill mentioned up there is probably broken (especially if it's also plastic). Time to find a good amp tech and have a for-real metal switch installed.

billfitzmaurice · #19 05-11-2011, 07:42 PM

A techie can drill a hole in the front panel next to the volume control and install a switch there. The alternative is to find an exact replacement switched pot.