Help..Marshall mg15cdr ticking constantly

[mosthigh]

I have a marshall mg15cdr that ticks incessantly, whether a guitar is plugged in or not.
Very rapidly when I first turn it on and then it slows bit within two seconds or so.

It doesn't seem to respond when I turn the volume, gain, reverb or EQ pots. Nor when I toggle the overdrive select button.

It does get slightly louder if I toggle FDD button, which is Marshall's Frequency dependant damping switch. ( Mimics the way a valve-state amp interacts with the speaker). But its because the overall volume gets louder.

Has anyone come across anything like this, or can anyone deduce what might cause this kind of clicking from my description.

Any help is appreciated, because I don't know where to start.

Thanks all......

[Enzo]

Take it to a friend's house. Does it still do it there? We want to make sure the amp is not just picking up electrical noise.

Also, you don't happen to sit your cell phone on top of the amp wwhile you play, do you?

[Gtr_tech]

Sounds like phone EMI to me. iPhones especially seem to emit alot of noise. My LG phone doesn't seem to cause problems with anything....

[Chuck H]

I thought the same thing when I read the title. But the OP reports a consistent pattern relative to turning the amp on. Unless someone with the interfering device is watching through the window and clowning the OP I'm not sure about EMI as the cause.

Still, do try the amp in another location just to be sure.

[mosthigh]

Thanks for the replies.

I tried it out in a new location as far from any electronic interference as possible and with my cell 4 rooms away.

Still ticking away!

I thought the same thing when I read the title. But the OP reports a consistent pattern relative to turning the amp on. Unless someone with the interfering device is watching through the window and clowning the OP I'm not sure about EMI as the cause.

Still, do try the amp in another location just to be sure.

Chuck, what do you mean by OP?

[Chuck H]

OP=original post or original poster.

Got a schem???

[mosthigh]

OP=original post or original poster.

Got a schem???

Okay... That should've been obvious huh, thanks for your patience.

Yeah, I do have the schem for it. I'm just not sure where to start with it because I don't know what would cause this kind of thing.

[Chuck H]

The schem would be for us... So we may see what it is in the circuit that might cause the problem.

[mosthigh]

One schem coming up..

Thanks again!

[acorkos]

does it tick if you are listening through headphones via the headphone out jack?

also, if you connect a guitar cable from your line out into another amp, do you hear the ticking in the second amp?

your findings can help narrow down where in the circuit the noise is coming from

[mosthigh]

does it tick if you are listening through headphones via the headphone out jack?

also, if you connect a guitar cable from your line out into another amp, do you hear the ticking in the second amp?

your findings can help narrow down where in the circuit the noise is coming from

It does tick through the headphone jack also.

And unfortunately, I don't have another amp to test with until a friend gets back from a trip.

[mosthigh]

This is a new development:

The sound is getting a little weird. Sort of like a blown speaker.
And the volume isn't going as loud as it did.

I may be in over my head at this point. Maybe time to take it to a local shop.....

[Chuck H]

Maybe. Testing the in/out jacks would help narrow it some, but I think injecting signal at different points and using a scope would be the only accurate way. AFAIK nothing I saw on the schem should be prone to that activity.

[Enzo]

And a little practice amp like that doesn't use voltages high enough to be arcing, at least not likely.