Foot Switch in MSZW Marshall Zakk Wylde Mini Stack Head

[sikaudio_com]

G'day.
  Now before I begin.....I have had a few people tell me
1. "Dont mod it, its a discontinued Signature amp   or  
2. "its not worth it, get a bigger & better amp"

-->1.  I dont care, I love modding ALL my gear
-->2.  I already have a Marshall EL34 50/50 with JMP1 & JFX,
& GX700 with Boss EQ all rack mounted, & An Ashdown UK made Fallen Angel.
(all Modded & Hot-Rodded of course...except the JFX) So I got that covered.

So, that said....what I am wanting is a single footswitch wired into the MSZW Mini Marshall Stack Head (a "Pretty" MG15 I believe...)
I want to be able to switch channels with a little footswitch....simple, I hope
 Anyone done this or know how to?

Schemtaic for MG15    -->   http://www.sikaudio.com/images/marshall_mg15_schematic.jpg   

 Cheers in advance for any help.
Nath

[Enzo]

Well, then, I don;t care if you want to mod your stuff either, go right ahead.

In your drawing, you highlight one half of the channel switch, but ignored the other half.  The other half of the switch selects which volume control is in use, and by extension whether the extra gain stage is in the circuit.

In clean mode, R48 is added in to reduce the signal feeding into the OD stage, that is SW1-B.  And in clean mode, SW1-A selects the clean volume.  Switching to dirt channel, R48 is shorted across, removing it from the circuit, and SW1-A selects the OD volume control, which uses the signal from the extra gain stage.

Your schematic is partial, so I don;t know if there are more things SW1 controls, I suspect there are no more sections to it.  SO SW1 is a DPDT switch.  The most straightforward way to do this in my view is with a relay.  Get a little DPDT relay, and wire the contacts in place of the switch.  YOu lose the switch on the control panel, so you must always use a footswitch for channel switching, but there you go.   We could wire up something so the panel switch remains and we have footswitching, but that would add to the complexity of the circuit we invent.  I suppose we could retain SW1, after reusing its solder pads, and have it controling the relay.

I can;t see the power supply other than to spot +15v.  I am guessing that derives from 20-25v somewhere?  ANyway, a 12v relay coil with a series ressistor would run fine off 15 or maybe a 24v relay off the 20-25v.  Tiny 12v relays are more common, but you can source anything.  A simple stomp switch would turn it on and off.

Alternatively, you could use three JFETs in place of the switch, and control their gates with a footswitch.  Same discussion about the panel switch being used or not..

[sikaudio_com]

Alright.... a little more complicated than I thought....but still pretty simple.
Thanks heaps for all that info enzo...Legend!
 Here is a link to the full schematic of the MG15 (same as the MSZW Head,  I'm sure)
http://home.exetel.com.au/sikaudio/Marshall_Mg15cd_ISS5.pdf

Yep I'm cool with only using the footswitch for channel switching....& bypassing the front Panel.
  I have a simple Stomp footswitch pedal.
  So,  I need to get a DPDT 12v Relay & then replace the Front Panel Switch with that...?
   Like a DPDT 6.35mm Full Switched Jack socket?

 Not 100% sure about the pin config & what pins go to the Footswitch Socket/jack?
   Thanks again for your tricky advice mate.....I would take it into some one to do this little Mod,
but there are No Techies around my area....I just do what I can do.
  I will upload a photo of the new DPDT relay (when I get one) & the place on the board I need to solder it....then I
might need a little more guidance from the Wiser Ones....
Cheers.


   
 

[J M Fahey]

Hi.
1) Please post the full schematic, so we can see whether it's actually a standard MG15 or not.
2) The words "mini" and "Zakk Wylde" should NOT be used in the same sentence [] ..... unless that mini comes loaded with an EVM12LII Black Label, of course.

[sikaudio_com]

Hi.
2) The words "mini" and "Zakk Wylde" should NOT be used in the same sentence [] ..... unless that mini comes loaded with an EVM12LII Black Label, of course.

Ba Ha ha ....Very true!  I agree.

 Yep, I posted the LINK to the full schematic above.
Its the MG15CD MG3 marshall schematic  (pretty much the same as the Zakk Micro Stack...so I have been told)
Here it is again....  http://home.exetel.com.au/sikaudio/Marshall_Mg15cd_ISS5.pdf
         (Slow server...so might take 30-40 secs to fully load the PDF file. )

Here are some Photos of the Switch & Board....

http://home.exetel.com.au/sikaudio/pix/marshall_MSZW15_f-switch_mod.jpg
http://home.exetel.com.au/sikaudio/pix/mszw_15.jpg

Cheers.

[sikaudio_com]

....MSMG15 Schematic image:   http://home.exetel.com.au/sikaudio/pix/MSMG15_schematic.jpg

For .PDF schematic  see above post.

Cheers.