Question about Marshall Amplification Marshall AR-AM4, 1RU Rack Mountable 4 Channel Analog Audio Monitoring System, with 4 Analog XLR Inputs & 1 Passive XLR Output

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What would cause my Marshall Mode 4 amp to not change channels?

When the pedal is plugged in, it will not change from "crunch" mode. Both the clean and crunch lights are on as well. Again, it is a Marshall Mode 4 guitar amp.

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  • Marshall Amp... Master
  • 30,787 Answers

That can be caused by a faulty switch contact. I presume channels can be selected manually.

Posted on Aug 05, 2014

  • Kris Hype
    Kris Hype Aug 06, 2014

    Channels will only change from a combined "Clean" and "Crunch" to the Overdrive.

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6 Suggested Answers

6ya6ya

6ya staff

  • 2 Answers

SOURCE:

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Posted on Jan 02, 2017

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thunder1962

David C. Peters

  • 1 Answer

SOURCE: marshall MG30FX loud tapping sound in time with delay even when no guitar plugged in and effects turned off

Hi J Wade. I'm Dave P. I'm not a guitar amp expert or technician but I've been using amps and effects for 35 years and there are a couple things I can suggest.

That kind of periodic noise/switch noise can be a symptom of having the polarity of the amp reversed. If your amp has a 3-position OFF/ground switch, try reversing the ground. If it doesn't, take the plug and turn it around. Just don't get near a microphone unless you're sure your amp is grounded the same as the P.A. It could fry your lips off.

Dirty switches to that too. You said the noise is in time with the delay's tap time which is set by a foot switch. If tapping that switch the first time generates a pop, the delay may have catch it and is repeating it. Turn off the amp, remove the delay foot switch and turn it back on. Still noisy? If not, give the foot switch a good cleaning.

When you turn the EFFECTS knob up, is it scratchy? Might need the potentiometer cleaned. What happens when you specifically turn the DELAY level down all the way while using the other effects? Noise still there?

That's all I've got. Hopefully, it was helpful. Don't wrack your brain over this too much. There could very well be an internal problem with your amp that will require a trip to the shop. You don't want to open it up yourself. Rock on but be safe.

Dave P.

Posted on Aug 22, 2012

Testimonial: "Very fast and useful response. Thanks for the help."

Fred Yearian

  • 5603 Answers

SOURCE: Hey, the clean channel on my Marshall 250dfx Combo

The switching is done electronically by an analog gate chip. On IC9, check if the signal on pin 8 changes with switching between clean and OD... This is the actual signal that changes the gate. If you don't see a change there of say 5 volts, then the problem is in the circuits that drive this gate. If the signal is there, then the problem is in the clean channel audio op amps or the components around them. Let me know the results of the test.

Posted on Oct 22, 2010

Fred Yearian

  • 5603 Answers

SOURCE: I've had (i don't know

Make sure the pedal and the amp ae compatible. MANY pedals can only be used with one type and model amp. If this was used with a different model amp originally, it is probably incompatible with the ine you are trying to use it with now.

Posted on Jan 23, 2011

TubeAmpGuy

  • 7 Answers

SOURCE: I got a Marshall

I haven't played or worked on a MG100HFX but I understand amp circuits very well. The behavior you are describing sounds to me like a bad capacitor in the Treble circuit. This is a problem that would require the skills of an experienced amp tech. If you are within your warranty period you might want to return it. If not, a good local repair shop should be able to diagnose the problem.

Good luck and keep rockin'!

Posted on Mar 01, 2011

Fred Yearian

  • 5603 Answers

SOURCE: I have an MG30 FX

Typically ONLY one effect will be active at a time unless there is a specific mixed effect available. The gain levels between the different effects are often not too consistent. In summation, this is probably the nature of the beast.

Posted on Mar 12, 2011

Testimonial: "Didn't expect help to arrive so soon! Clear and concise answer is just what I needed. Read the manual once more. Now everything's ok. Thanks!"

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