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1974x footswitch

Posted: 05 Mar 2014, 08:01
by sundayamp
Marshall 1974x picks up radio frequencies when I plug I. The tremolo footswitch. How can this be fixed??
Thanks

Re: 1974x footswitch

Posted: 05 Mar 2014, 08:59
by Wildone
RFI (radio frequency interference) is usually caused by bad cables, bad solder joints, long unshielded wires from the input jack to the first tube and/or bad ground, no "grid stopper" resistor on the grid of the first preamp tube, or no tube shields on the tubes. In some cases, RFI can get in on the AC mains. Possible fixes:



First, unplug the cable to see if the RFI goes away. If so, it is likely the cable or the guitar picking it up, or lack of grid stopper resistor on the first tube.

Re: 1974x footswitch

Posted: 05 Mar 2014, 09:14
by sundayamp
When i unplug the footswitch cable the radio signals go away. Also, i hear the RFI even if the guitar isnt plugged in! I wouldnt mind leaving it unplugged but i cant turn off the tremolo effect when it is unplugged and i like the sound of the tremolo channnel without the tremolo effect

Re: 1974x footswitch

Posted: 05 Mar 2014, 11:04
by sikter
It's shoud be an easy fix!
Replace your foot switch cable with an instrument cable.
(Shielded one)

Re: 1974x footswitch

Posted: 05 Mar 2014, 12:44
by sundayamp
I'll put on one of my spare guitar cables. Thanks a lot for the help!!!