Tourmaster footswitch question

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knot

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Hi,

I am a new user of the Tourmaster 4100 head, and I have a few questions about how the footswitch works, because I want to build another (different) one. I want a 2 button (3PDT and DPDT latched buttons) footswitch. With first button i control CV or OD channels, and with the second button, the first or second channel. With another 4 additional switches (SPST), i switch on/off the loop for each channel. It's a way to automatize the loop switching without using midi.

John sent me the pinout schematic, and explained me how to control the channels, the reverb and the loop closing different pins, but i didn't understand clearly what "close" means (I suppose that means to connect the pin to +12 VDC). Anyone could please explain it?

Another question...I want to use leds, but in the pinout schematic there is no 0 VDC pin. So i suppose that in the original footswitch the leds are in serial with the switch that closes 12 VDC and each pin. The problem is that in channel CV1 both pins that control the channel switching are open, and i don't know where the led could be connected.

Thanks.
 
Pressing on a switch latches or unlatches it.

I.e. completes (closed) a circuit, or interrupts it (leaves it open).

Very hard question though to answer without seeing the schematic/layout.
 
just get 3pdt switches for the whole thing.

you'd need at least dpdt switches to make lights work. post the schematic if you can
 
I did have a Marshall TSL back in the day, and the footswitch used momentary unlatching switches. I guess the switch, when momentarily closed, shot a "pulse" of energy that changed the channel?

Man that thing was a piece of sh*t. There was like a half second delay when you changed channels. That drove me absolutely insane.
 
Hi,

I attach a schematic of the footswitch i want to build.


thanks.
 

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I'm trying to wrap my head around this and help you out, but it's kinda tough. Can you post a schematic of the original as well?
 
I haven't got the original schematic of the original TM4100 footswitch. It has six (unlatched) switches, four to control each channel, and another two to control the loop and the reverb. I suppose that it contains some kind of electronic that controls the four relays needed, two for the channels (the four channels are controlled by the combination of two open or closed pins) and two for the loop and reverb.
The idea of buid a different (and simpler) one is because most of the time i only change between OD1 and OD2, but i need the loop off with OD1 and the loop on with OD2 and i want to push only one switch. This could be achieved with only one SPST switch, but i added more possibilities to the first idea, like switching to the CV channels and linking the loop switching wich the desired channel.
 
Yeah, I hear ya. Don't get me wrong, it's a fantastic idea. But it just seems like a ton of work to do, for something that CAN easily be accomplished using MIDI.

And I'm not even the biggest MIDI fan at all... Eric knows that! :lol: :LOL:
 
RockStarNick":x1ufm9ey said:
Yeah, I hear ya. Don't get me wrong, it's a fantastic idea. But it just seems like a ton of work to do, for something that CAN easily be accomplished using MIDI.

And I'm not even the biggest MIDI fan at all... Eric knows that! :lol: :LOL:
Click to expand...

HAHAHA.. Yeah. I would totally do this w/ MIDI. It'd be much easier and most likely cheaper too.

Eric
 
If i had a midi switcher to control the TM4100 and a midi footswich controller, i wouldn't try to build a new footswitch. And with midi is not as cheaper as 20 €...

I only need to know if i can place the leds there in the schematic... or the voltage drop will be a problem...
 
knot":2c1igtr7 said:
If i had a midi switcher to control the TM4100 and a midi footswich controller, i wouldn't try to build a new footswitch. And with midi is not as cheaper as 20 €...

I only need to know if i can place the leds there in the schematic... or the voltage drop will be a problem...
Click to expand...

Yeah...it's not gonna be $20 whatever...but man...you can get a 4 button midi controller from randall for cheap...and get a rolls unit, which sell for $50-60 used. That solves your problem. The Randall 4-button controller is midi..and the rolls could do what you are needing for cheap. There's already a guy (evink) that has done it already.

Build it if you want though.

Eric
 
Knot.... Voltage drops will not be an issue with this 12volt low amperage system the tourmaster footswitch uses. You are correct in the leds being in series with the closed circuit. Closed merely meaning a completed circuit as i noticed you asked in one of the posts.

I chose to design a midi breakout box for mine that converts the original footswitch cable to 4-1/4inch plugs that go to my rolls switcher because I use so many effects with different channels.

Your design using the switch you have planned will also do the same thing. ALl your doing is merely connecting and disconnecting a couple cables IF your only wanting this for the two OD channels.

Your posts says you merely want one switch to go from over drive one on with no loop and OD 2 on with loop. You would also only need one led light in line with the OD 2 channel to show that it is hot and thus also adding your effects loop as well.

However as you deside to get this thing more complicated with the CV channels why not just mod the original foot pedal with a few simple jumpers that would allow your to eliminate the loop switch. It would be there and could be used but the jumper from the OD 2 switch could be tied in with the loop switch and once it is hit would then bring in the effects loops as well. You could do the same type mod for the particular CV channes as well and whammo two switches on the original foot pedal would do the trick and all you have is the small cost of some short 22 gauge wire lenghts and some solder.

I can draw up a wire schematic over the weekend if you would like to see how that can be done. I am sure since you designed this foot pedal schematic that you are capable of figuring this out though. Would be cool to have the original foot switch do it all and save you the cost.

I just use too much outboard effects for all 4 of my channels to get by not using midi. I will say midi with a rolls unit will give you way more flexability for the future though. Let me know if this idea of mod'in the original foot switch pans out for you man.

Kevo
 
By the way I forgot to mention that the footswitch has no special circuits in it at all. I know there was once post you mentioned maybe it uses some special circuitry. It doesn't for the switching functions at all. Merely uses latching switches that complete a circuit one channel at a time.

Make sure any mods you do will not allow more than one channel to back feed a competed circuit or the amp might wig out not knowing what channel it wants to use.
 
Hi evink1, thanks for your reply.

I have already bought the components, so for now i am not going to mod the original footswitch. I think i understand your idea, you mean to wire a jumper to send the desired channel signal also to the loop pin, isn't it? I'm sure it would work ok.

What I am still not sure, is about the way the footswitch works. There are four switches to control two pins combinations, wich determine the channel switched on:

CV1 CV2 OD1 OD2
Pin 2 open open close close
Pin 4 open close open close

I think that it uses some special circuitry because two reasons: If the switches are latched ones, it could be being pressed more than one switch at a time and it wouldn't work, because if you have the switches in serial, can't close a pin if another is opening it and in parallel, the opposite. And if the switches are unlatched ones (as i think), the signal sent to the amp is not continuous (in time), when you release the switch the signal ends. And if i have understood correctly, the pins may be closed or open to determine the selected channel.

If someone had the original footswitch schematic, it would be easier...

Thanks for your help, and sorry for my english... i do my best.
 
No it really is just completeing the proper grounds in the combination that the amp needs to see to flip the negative side of little relays inside the amp. Those relays merely direct the signal through the proper channel in the amp. It really is a simple footswitch design. You merely ground the proper wires in the right combination and whammo it switches.

My midi breakout box through my rolls switcher does actually latch the combinations together and it works perfect that way. That is how they can get the footswitch to do so much with only a few wires 7 of the 8 pins actuall do something. Any special circuitry is inside the actual amp and it really is only relays that when grounded in the proper pattern via the foot switch it turns on and off the proper relays to do the switching.

Bruce keeps all this stuff fairly simple so it just works and doesn't add any RF interferences into the amp. I say fairly simple because in theory it is but there is quite a bit of stuff going on to cause this to work but trust me as far as the footswitch is concerned it is only completing grounds in the proper combinations.
 
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