SOLVED Making a footswitch for my Ampeg Rocket Bass 115

[MBFX]

I want to make a footswitch for my Ampeg Rocket Bass 115. That should be very simple, according to the helpful schematic provided in the user manual:



I figured I would try my Mesa Boogie footswitch for my Mini Rectifier, the FC.TS, which is a single button TS footswitch with an indicator LED. Should work, right? Turns out no, it does not. When I plug it in, the LED stays lit and SGT stays on regardless of how many times I click the switch. I don't understand why it isn't working, because the recommended Ampeg product is a 2-button, TRS, lighted footswitch that only uses the left button with this amp. The Mesa footswitch works with the Mesa amp.

When I plug in a TS cable to the footswitch jack by itself, SGT turns on. If I jumper the tip to sleeve, it turns off. WTF? All I want is a lighted footswitch. Sure, I can make an unlit one, but that sucks. Any ideas?

 

[DailyDovetails]

I think you could do a DPDT ON/ON and do it like this. You could even use a 3PDT and ignore third lugs.

 

[MBFX]

I think you could do a DPDT ON/ON and do it like this. You could even use a 3PDT and ignore third lugs.
View attachment 86506

I'm not sure where voltage is coming from there - according to the diagram Ampeg provided, we only have two conductors to work with. Is voltage potentially on the tip, and I bridge the two center connectors?

When I get home I'll plug a cable in, and test the voltage/see where positive is. I know that bridging the connection turns SGT off, so the LED will go on the opposite side of the switch from the T/S junction. I'll need a ground, too, for the LED.

 

[DailyDovetails]

I'm not sure where voltage is coming from there - according to the diagram Ampeg provided, we only have two conductors to work with. Is voltage potentially on the tip, and I bridge the two center connectors?

When I get home I'll plug a cable in, and test the voltage/see where positive is. I know that bridging the connection turns SGT off, so the LED will go on the opposite side of the switch from the T/S junction. I'll need a ground, too, for the LED.

I might have misunderstood I assumed it would run a dc adapter or battery for the LED.

 

[MBFX]

Ah, yes, we did miscommunicate. The switch lights up without any external power - both my Mesa switch, as well as the stock Ampeg switch I want to emulate

 

[DailyDovetails]

That makes me wonder is it possible it just an inline led with an on off switch. I wonder what would happen if you tried jumping it across with an LED?

I didn’t realize there were foot switches that worked like this. I have had the same non light up Marshall for 20 or so years now. I’m going to have to see if my amp can do this.

 

[DailyDovetails]

This schematic works on my Marshall DSL. It lights up when open and the light goes out and channel changes when closed. I’m guessing it will work on yours. Now I have new footswitch on my todo list.

 

[andrewsrea]

^ This. A standard DPST stomp switch will work.

The tip carries the led voltage and also keeps the amp bypass switch in the open position. When the stomp switch is closed, it shorts the tip to ground, I suspect the switch in the amp is a relay and the LEDs operate by passing a little current to ground from the open relay coil, through the LED.

Plug in a guitar or speaker cable to the FS jack and measure the voltage between the tip and sleeve of the other end. Let us know what it reads.

 

[Nostradoomus]

The schematic for ampeg footswitches is freely available, in your case probably the AFP-1, which is like what @DailyDovetails posted

Ampeg – Bass guitar amplification

Ampeg is a Bass amp instrument manufacturing company that specializes in bass guitar amplification and effects. For over 60 years Ampeg has been providing amplification solutions for professional bass players and aspiring bassists looking for the best bass practice amps.

ampeg.com

 

[MBFX]

Hello everybody! I had a long week, and just now got to sit down and mess with this. I have confirmed that it is definitely a TS connector, that voltage is on the tip, and that shorting tip to sleeve turns the SGT effect off. Tip to sleeve voltage measured 12.58VDC. Thus, I will make a very simple box:



That should work, I think. It will definitely turn the channel on and off, and if I understand correctly, the LED will only come on when the tip and sleeve are disconnected.... right? I'm still a noob at circuit theory, even basic stuff like this. I feel like I might have the switch wiring wrong, vis a vis the LED. As far as I understand, when tip is connected to sleeve we have a dead short, and the LED is off. When we break that dead short, the LED is on. Am I doing this right? Lol

EDIT: pretend there is a current limiting resistor attached to the LED in the image

 

[Stickman393]

No need for a CLR. There isn't one in the ampeg schematic.

The way this works is pretty simple: A SPST would work. It has to be latching, though. Not momentary.

When the switch is opened, current flows through the LED to ground. The LED creates a voltage drop, my best guess is that there's a load in series here that is not energized when the LED is powered.

When the switch is closed, a path is created that bypasses the LED. The LED turns off, as current takes the path of least resistance. If I'm correct about the above, then the load is energized at this point.

Could be transistor based, could be relay based. Dunno. But it's an elegantly simple solution to a low parts count switching system with an indicator LED.

Your schematic should work.

 

[MBFX]

No need for a CLR. There isn't one in the ampeg schematic.

The way this works is pretty simple: A SPST would work. It has to be latching, though. Not momentary.

When the switch is opened, current flows through the LED to ground. The LED creates a voltage drop, my best guess is that there's a load in series here that is not energized when the LED is powered.

When the switch is closed, a path is created that bypasses the LED. The LED turns off, as current takes the path of least resistance. If I'm correct about the above, then the load is energized at this point.

Could be transistor based, could be relay based. Dunno. But it's an elegantly simple solution to a low parts count switching system with an indicator LED.

Your schematic should work.

Thank you! I used a DPDT because that's what I have on-hand, but I'm ignoring half of it. I think it's relay-based, but the click I hear could also just be my joints

 

[Stickman393]

Thank you! I used a DPDT because that's what I have on-hand, but I'm ignoring half of it. I think it's relay-based, but the click I hear could also just be my joints

That would make sense to me, switching an LED in series with a relay coil would be an easy way to disengage the relay.

Rock on brotha.

 

[MBFX]

It works!