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The Fender Hot Rod Deluxe shows a 2-button footswitch as standard but I'm confused. This link shows it as connected to the amp via a mono cable ... FENDER Hot Rod Deluxe DeVille Footswitch which is impossible using two switches. Normally it's a stereo (tip, ring, sleeve) with tip to sleeve being one connection, and ring to sleeve the other. Good luck with this one.
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.
Does your M foot switch work on the Fender? If you know how to use a multimeter you could check continuity by putting meter leads on plug of M foot switch(1 on tip, 1 on sleeve ) You should see a change in the multi meter when you depress switch. If so switch is good. Another easy test is with cap off a spare 1/4 plug -plug it in to foot switch jack.put a alligator or some such metal clip or wire and join(called short or shorting) the two inputs . If connecting and unconnecting results in switching then the foot switch is suspect. One fairly common thing is that foot switch and input jack are often sautered straight to a circuit board to save $ on production cost. Used to be all point to point where a wire was attached to 1/4" input and then wire went to circuit board or tubes. The wire has give, but not so with direct wiring to board. So the nut holding the 1/4" amp input gets loose(doesn't have to be loose for the following to happen) and a pull on the chord causes a break in the soldier and thus a break in the sound chain. Sometimes it will work intermittingly by putting a little pressure left, right, up or down on the plugged in plug. If so, it's the input jacks connection to the amp. If not it still could be that because putting pressure on plug may not be sufficient to affect a temporary reconnection. Since switch(the new one you made)works on Fender, but not Marshall I suspect the jack or foot switch circuitry past the input jack. If using some of the above the above tests leads you that direction,remove housing(unplug a/c power 1st ) inspect jack,wiggle it slightly see or feel a break then resodier from back side. You should be able to use the soldier already present without adding extra.
That supposedly is the correct footswitch for the amp... there may be a defect in the amp. Contact the factory support about this problem. Make sure you are FULLY plugging in the plug as SOMETIMES they feel like they are clear in but they are not.
I would expect a problem with the power to the display. I believe these had LED displays and they use a reasonable amount of current. I would expect he power source for the display has a bad source of power. If poowered by an adapter, possibly the wrong adapter is being used with insufficient current capability or if powered from teh amp, then maybe the wire that brings the display power down is broken or a connector for that cable has a problem.
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.
Here is the schematic:http://www.ampix.org/albums/userpics/10003/MArshall_MG100DFX.pdf There are a few possibilities.The jack for the footswitch for channel changing JS1 might be faulty. Zener diodes 1 and/or 2 might be faulty. Switch 2 may be defective. TR1 might be defective. IC 4 or 5 might be defective.Start with the channel switching circuitry testing in the order I gave you. Check the actual clean channel circuitry to see if you actually have a clean channel anymore. Before you do any of this make sure you know enough about troubleshooting and have at least a good VOM and are familiar with safety procedures. The filter capacitors in this amp store enough charge to kill you. A cheat to partially discharge them without damaging the amp is to unplug it from the wall while it is hooked up to the speaker cab you are using while it is on at a very low volume with a guitar cord plugged in. Make sure you use exact replacement parts if you tackle this. They don't have to be from Marshall, they just have to be exact electronic equivalents from a quality manufacturer installed correctly. I would recommend that if you have no experience or are at all unsure of the repair to take it to a Marshall dealer to have it done. Please rate me if this helps.
Hi there. Check the foot switch. Plugged in all the way? Still not working? Use an ohm meter to check the foot switch. (unplug from amp and check for continuity across the plug. click switch on and off.) If alway open (no continuity) bad switch. Thanks Paul
Replace the switch. You gave no make/model number for your amp but if it has a jack for foot pedal operation of clean/dist function then try that. (on most amps) it will switch in spite of a bad front panel switch.
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