Runt 20 footswitch LED switching is backwards

  • Thread starter Thread starter BackCrack
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BackCrack

BackCrack

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I have a buddy that recently picked up a Runt 20 combo. The footswitch's red LED lights up when the combo is on the clean channel. Is this a common thing? Can it be changed inside in the footswitch or does the switching logic have to be changed inside the amp?
 
The LED in the BE100 does the same.

The LED is in series with the switch. You would need to rewire the foot switch so the LED is in parallel with the switch. But you have to add a large enough resistor in series with the LED so that it will allow the relay to disengage. Try a 2.7k, if that does not allow the relay to disengage move up to a 4.7k

BTW: If you open the footswitch and the LED is already in parallel with the switch, then remove the resistor, and wire the LED in series with the switch.
 
I had my buddy check it just now. The LED and jack are wired parallel to the switch. There's a 4.7k resistor in series with the LED.
 
Alright then you should be able to rewire the footswitch with the LED in series with the switch. You would omit the 4.7k resister because the relay coil acts as a current limiter at about 950R.
 
Thanks for your help on this.

Update: he dropped off the amp and ftsw last night for me to tinker with. I re-soldered the ftsw this morning so that the switch and LED are in series and left out the 4.7k. The light does toggle on/off, but the channels on the amp don't switch. The clean channel stays on, regardless of the ftsw and the panel switch position. I'm thinking maybe adding back in the 4.7k?
 
Try the 4.7k across (parallel) the LED. if that does not work, use a smaller resistor until it does. (you could also parallel another LED with the current LED instead of the resistor)

The LED is causing too much voltage drop to engage the relay.
 
I had the same issue with a non friedman head some years ago. I just rewired the switch to the opposite poles and problem was solved... maybe that wont work here? I've not opened my friedman footswitches to see what kind of switch is used.

Btw the footswitch on my runt 50 operates the same way, I just haven't bothered with trying to change it.
 
thats how it is suppose to operate.
completely normal.
my be 100 is the same.
 
update: I tried everything I could think of. Series, parallel, resistor loads from 1 ohm to 10k. I finally gave up, went back to stock, and swapped out the red LED for a green one to indicate the clean channel is on. Backwards logic for my brain, having a light turn on for less gain (like Mesa's old ftsw). Oh well.
 
I remember seeing a post from Dave on how to correct that and it seemed really simple.
 
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