20 Most Recent MXR Carbon Copy Analog Delay Pedal Guitar Questions & Answers

I can't see any reason to do that unless the battery gets old. When you plug in the adapter, it automatically switches off the battery.

Most common problem is the in and out cables are backward to cause this.

First thing to test: Do all the controls vary their function smoothly or does say the volume control vary the output only slightly. If the latter condition exists I would open the pedal and look for broken solder around one lead of the volume pot. The broken solder is hard to see... look for a little grey line on the menicus of the solder filet around each lead. Also look for cracks in the circuit board. Use a bright light.

DO NOT count on a "new" battery to be good! I always carry an inexpensive meter (about $3 from Harbor Freight) to test batteries. Try yet another battery...
A common failure however is that the wires to some of the battery clips break after having to fight with 9 volt battery clip removal that have wires... The ones without wires have a habit of not making contact at time...

Here is a schematic that may help:http://www.schematicheaven.com/effects/mxr_dist_plus.pdf

The most likely case is that one of the main output transistors (if which there are many) is shorted. When the protect circuit senses DC on the final output, it will not allow the output relay to come on to protect the speakers from raw DC. With the power removed, you can check between each outputs Emitter and Collector and you will probably find close to zero ohms. From that point you need to unsolder each of the pins of the bad channel until you find the shorted device(s) and replace them.

'pianoforte'

BREV. N. 838420

See page 22 troubleshooting of this manual. It may help you. dd501 (yamaha.com)

Depending on the model, there are four around that date, it could be the insert jacks are tarnished reducing the signal flow between the pre amp stage and digital power amplifier. It could be the power amplifier has failed. It could even be customer error in wiring. This assumes there is the correct level of signal entering the input sockets of course.

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It's a Line 6 and probably requires a software update from Line 6.