foot switch schematic for marshall mg30dfx

[ghoshsubha444@gmail.com]

hello,

a friend of mine owns a marshall mg30dfx amplifier. He is quite frustrated with the manual switching between clean and dirty in the middle of a song while he is playing something. so it would be a great help if some one can post the schematic for marshall 30dfx foot switch. any kind of idea is helpful for me..

 

thanks in advance

[Enzo]

It's a switch in a box.

resolder the footswitch jack, make sure the cutout contacts on the jack are making well.  Check the solder and contact resistance on the panel switch.

[ghoshsubha444@gmail.com]

It's a switch in a box.

resolder the footswitch jack, make sure the cutout contacts on the jack are making well.  Check the solder and contact resistance on the panel switch.

hello enzo,

thank you for your kind reply. actually this amp contains a dedicated input only for footswich. and i was asking for schematic of that box. so that i dont have to open the chassis of the amplifier and to modify the existing board.

according to the manual supplied with it says it uses P801 footswitch and which is unavilable in my local place in india

I am uploading a picture of this amp for the reference..

Thanks

[J M Fahey]

That's what Enzo means  :cheesy:
The "schematic" is a footswitch shorting or not an 1/4" guitar plug.
What's the FSW supposed to switch?
Channel/dist/gain/boost/reverb?
Plug a stereo plug into the FSW jack and alternatively ground one or the other terminal (tip or ring) with a piece of wire ... any change?
Once you've confirmed this, the pedal wiring is using 1 (or 2) switches to duplicate the shorting previously tested "by hand".

EDIT: *some* pedals are more complex than that, such as Fender, which have internal Leds and a diode matrix so 1 wire controls 2 functions (clever) but afaik "small" Marshalls use simple generic switches.

Now, say, the one in an MF350 uses a 15 pin connector, multiwire cable, has some 5 switches , Leds, etc. ... but thanks God it's not the case here.

[Enzo]

Exactly.  The footswitch is nothing but a switch in a box, with a wire that plugs into the amp.   It shorts across the jack or not depending upon its position.   So ther is no schematic to draw, other than an on/off switch.

My suggestion centered on your symptom.  If I read you correctly, the amp likes to change channels all by itself, when you don;t want it to.  My thought was that the footswitch jack itself may be at fault.  If the solder is cracked under the jack or the jack is sprung, then the connections into the control circuits will be intermittant.  And that will cause your problem.  Also, the panel switch for channel selection could be loose or have cracked solder and also cause problems.

[ghoshsubha444@gmail.com]

That's what Enzo means  :cheesy:
The "schematic" is a footswitch shorting or not an 1/4" guitar plug.
What's the FSW supposed to switch?
Channel/dist/gain/boost/reverb?
Plug a stereo plug into the FSW jack and alternatively ground one or the other terminal (tip or ring) with a piece of wire ... any change?
Once you've confirmed this, the pedal wiring is using 1 (or 2) switches to duplicate the shorting previously tested "by hand".

EDIT: *some* pedals are more complex than that, such as Fender, which have internal Leds and a diode matrix so 1 wire controls 2 functions (clever) but afaik "small" Marshalls use simple generic switches.

Now, say, the one in an MF350 uses a 15 pin connector, multiwire cable, has some 5 switches , Leds, etc. ... but thanks God it's not the case here.

no its suppose to switch between clean and dirty channel

[Enzo]

Yes, we honestly do know what it does.  The amplifier schematic is clear.  The footswitch is nothing more than a switch in a box. really.

If you plug a simple plug into the footswitch jack on the amp and connect its tip to its sleeve, you will do exactly what the switch would do.  The footswitch is an on/off switch wired to a plug.