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?

Cheers in advance for any help.
Nath

[sikaudio_com]

[Enzo]

You have posted this somewhere else also, and wherever that was, I already answered there. SO go look at the other places you have the same posts up.

[sikaudio_com]

...Cheers Enzo. ....I'm After all the help I can get on this one.
Still in need of a little more guidance.


Now all I need to know is what pin on DPDT Switch --> goes to what points on the Marshall Board?
I will be running extension wires to run from board to switch, So I can mount the switch at back of amp.

[Enzo]

Well, your jack is not a switch, though it has some switching contacts. And it is not DPDT in any event.

I proposed a relay in the amp. The only jack we would be needing would be for a footswitch. The footswitch would turn the relay off and on.

The relay would be mounted right on the amp circuit board - probably glued on upside down, legs in the air, with short wires running from its pins. The "dead bug" mounting approach. You then must find a voltage source in teh amp to use for the relay coil.

I don;t know what relay you will find, they come in all shapes and sizes. This application is small signal, so you don't need bug clunking relays. But any relay data sheet will show you its pin arrangement. If you get out your ohm meter, it should be easy to determine the switching patter of the existing switch. In the purp-le box, there are 6 legs, the left column is one side and hte right column the other, The center pin of each column is the common terminal. SLide contacts inside connect the center to either the front or the rear leg by position.

[sikaudio_com]

Thanks again Enzo....you certainly do know your stuff!
So is there any chance of me using a Relay off the old Amp i got the Jack/Socket from?
Its a 15watt guitar amp that Had foot switching for the clean & OD channels.
I'll look into getting a new 12DC relay as well.
This F/S jack I got out of the other amp looked just like the "J227 DPDT jack Full Switched" socket I see here in my WES Components catalogue...
thats why i thought I had the DPDT relay & switch covered.
Thanks again mate.

[Enzo]

I don't know what amp you pulled the jack from. it may not have used relays for switching. It may have used transistors. There is a difference between designing an amp for channel switching by remote, and trying to add it to an existing amp. I like relays, they are easy to use and understand, but if I were designing this amp from scratch for footswitching channels I might pick a different method. You can look in it, a little rectangular thing with either a K number or something like RL or RY. In other words you see resistors marked R102, R103, etc, and caps C222, C233, etc, so a relay will be marked K101, or RY202 etc. I suspect it won;t have a relay.

The jack has extra contacts in it, so that when you plug in a cord, it turns other things on or off. That is very handy, but it doesn;t give us any control. It switches contacts when you plug in, and un-switches when you unplug. What yu want is soomething you can plug in and leave plugged in, and then a circuit to allow you to control the innards of the amp from afar.

I have attached the schematic to an old Peavey Audition Plus. It is a simple amp, and it uses a relay for channel switching very much like your amp would. Note in the drawing SW1a and SW1b. These switches work together in different places in the amp to switch channels - just like your amp. But these switches are not part of a pushbutton, they are within a relay. A relay is nothing more than a switch with an electromagnet to flip it.

The switches are shown with a dashed line linking them together and to the relay coil marked "relay." The coil in the relay is its electromagnet. RUn current through the coil and it magnetizes, causing the inside contacts to flip. The coil of the relay is the thing with 71322277 under it.

To control the relay, connect one end of the coil to a power supply - in this amp it will be 15v, so again similar to yours. Then ground the other end of the coil and it energizes. In this case they used a 12v relay, so that 270 ohm resustor in series with it is to knock the 15 volts down some.

Remember the switches inside the relay and the coil inside are linked mechanically only, they are not wired together in any way.

[sikaudio_com]

Sweet....I do like this relay idea. Your right, there is no Relay in the Other DEAN amp.
So, I will have to order a little $3.20 Relay & wait 5 days for it to arrive!

I just started an Electronics Course (so I can do a little more on these guitars & amps of mine) & I gotta tell ya,
I am learning more from you Mr. Enzo, than I am from the 8inch thick Text Books!

[Enzo]

Here you are learning some VERY specific things that pertain to this particular problem, but thosetext books will teach you the fundamentals, the underlying concepts upon which all this is built. When you understand those, then all circuits are understandable. When you know HOW things work and WHY, they the function of any circuit becomes clear.

There is nothing more basic than Ohm's Law, but then there is nothing more important either. I have been soldering for over 50 years, and learned my Ohm's Law back then, but still these many years later, I use OHm's Law EVERY DAY. Learn those basics.

[sikaudio_com]

...yeah true. I started learning OHMS LAW not too long ago....did my head in the first few days.
Then it starts all coming together. I imagine most of these electronic studies will be like this.

As I understand it.....I will be needing this DPDT Relay (see image)




http://home.exetel.com.au/sikaudio/pix/DPDT_relay.jpg

Just wanted to confirm before I order a couple of these.

Sure will be the cheapest Mod I have ever done....but the most complicated I have personally done.
I had a tricky Techie mate that helped me out with all my other mods....
but he's gone & done with it all now.

Cheers mate.

[Steve Conner]

I'd choose the "G2VN-12" "Miniature PCB DIL Relay" instead. Power relays with heavy contacts can be unreliable switching small audio signals.

I just finished teaching a semester of Electronics 101 to foreign students at the university where I work. I had a Vietnamese guy in my class called Ohmnath, but everyone called him Ohms for short. And one day he noticed, "Hey, it's my law!" I bet he remembers it.

So yes, if you remember one thing about electronics, make it Ohm's Law. If you can be bothered remembering another two, Kirchhoff's circuit laws. I bet Enzo uses these every day too, even if he doesn't know them by name.

Kirchhoff's voltage law: The sum of voltage sources (batteries, power supplies etc) around a circuit equals the sum of voltage drops (in resistances and other loads) (Follows from Ohm's law, the definition of electrical power, and the conservation of energy.)

Kirchhoff's current law: The sum of currents entering a circuit node equals the sum of currents leaving it. (Electricity doesn't pile up.)

If you work with electric circuits every day, you've probably absorbed these things on an intuitive level and they might seem like stating the obvious.

[sikaudio_com]

Cheers Steve!
Thanks heaps for that....I'll go with what ever Relay you suggest on this one.
Just been checking out your Amps.
Have you ever fooled around with Hybrid Amps?
Valve Preamp linked with Solid State Power Amp Section, with some good Power Chips?
I've always liked this idea for the Modern Hi Gain-Dropped tune stuff.
I know someone who is getting into this Hybrid stuff & loving it!
Getting real good results & a very versatile amp.

[sikaudio_com]

...love that NINJA TOASTER amp of yours....looks good!

scopeblog Ninja Töaster

...real good actually...I want one!
I just had my Ashdown Fallen Angel Modded with different Tubes, Choke, Orange Drops & some other EQing goodies.
....its a Beast of a High Gain amp!
What would you compare your NIJA to in the High gain area ?

[Steve Conner]

Not to jack the thread, but...

Yes, I've had good results with hybrid amps. They work well for metal. I bolted a valve preamp onto the front of an old Philips 150 watt PA amp, and it turned out a real nasty beast. Didn't clean up too well, though. When I built my first all-tube amp it blew the poor hybrid off the bandstand and I ended up dismantling it, but I was interested in other styles besides metal by then.

When I built my ninja amp I was trying to make something that sounded like a 5150 or one of the Mesa amps with the graphic EQ. The problem was that I never had any experience with those amps. If I could have bought one at the time, I wouldn't have had to build my own! I just knew what bands I liked and what amps they used. I still haven't really played other high-gain amps much.

[Enzo]

I know Kirkhoff. Electricity doesn;t pile up, but the work does.

As I deal in practical electronics, the "electricity doesn't pile up" never was very helpful. But the idea of voltage dividers is a fundamental right in there with Mr Ohm's law. KNowing that all the currents or voltages coming and going into a point add up to zero never helped me find out just WHERE the unwanted hum voltage was sneaking in from. On the other hand I suppose it helps explain why my meter gives erroneous readings when trying to measure voltage on a PI grid. (measure grid voltage to ground versus measure grid to cathode and the results will differ on the voltage you think is on the grid.)

Thevenin was the one that was least useful. It is a strong theoretical concept, but in a peractical shop setting, it is not how we look at things.