LED on Fender Champ 12 footswitch can be installed?

I´m trying to install a LED on the footswitch of my Fender Champ 12.


Footswitch has a single switch with a white and black wiring.


The Champ 12 panel turns a red light when GAIN channel is activated, and voltage on footswitch is 4.12v so I desoldered the white wire, install a red LED with a 100 ohm resistor this path:
white cable > 100R to LED anode > LED cathode to footswitch terminal.

Now if I turn on the GAIN channel the footswitch LED turns on and If I turn off the GAIN channel the LED turns off but the LED on the amp panel never turns off, It stays ON all the time, there´s some bleed on both channels and the GAIN channel has a massive volume drop.
What I´m doing wrong?
Thanks in advance

I'm not an electronics expert, but I had a look at the schematic for the Champ 12, and it looks like audio signal is passing through the footswitch when the overdrive is selected, so inserting the 100 ohm resistor may be causing the volume drop. I don't know why the LED on the amp would remain on all the time based on your modification.

Thanks. I´m not even a tech, but some time ago I added a pair of LEDs to my Marshall DSL40C footswitch just calculating the needed resistors value. I thought this time may be something similar.
I´d ask on a Fb page, and nobody has told me a circuit modification is needed. Even Bruce Egnater gently answered sayin "Should be able to place the pedal LED in series with the white wire. No added resistor" "Disconnect the white wire and insert the LED in line with it" he added.
I understood this: white wire > led anode > led cathode > footswitch terminal, but it does the same.

I looked inside of the footswitch pedal for a Princeton Chorus amp and it does have resistors in series with the LED's, but that is a totally different amp (solid state) and they probably do the channel switching with relays.

Here is a link to the best Champ 12 schematic I found. You can enlarge it on your screen to make it easier to read. http://www.prowessamplifiers.com/sch.../Champ_12.html

Quote:

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Originally Posted by Michael Smith

I looked inside of the footswitch pedal for a Princeton Chorus amp and it does have resistors in series with the LED's, but that is a totally different amp (solid state) and they probably do the channel switching with relays.

Here is a link to the best Champ 12 schematic I found. You can enlarge it on your screen to make it easier to read. http://www.prowessamplifiers.com/sch.../Champ_12.html

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Thank you

That schematic shows the switch, (with no resistance) to activate the "clean" side, with "open" circuit activating the LDR. Not the usual Fender switching I've worked with, (diode/resistance differences causing the different functions).
It may be easiest to use a double pole switch, and wire an LED/battery to the other pole.

This is way beyond my knowledge (or interest, for that matter), but I saw this and thought maybe it might help? There is a wiring diagram for download, too.

3PDT Foot Switch with LED Ring

Quote:

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Originally Posted by Bill Moore

That schematic shows the switch, (with no resistance) to activate the "clean" side, with "open" circuit activating the LDR. Not the usual Fender switching I've worked with, (diode/resistance differences causing the different functions).
It may be easiest to use a double pole switch, and wire an LED/battery to the other pole.

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I saw the 2 LDR's in the schematic, and didn't know what they did. Your idea of using a double pole switch is a good one. I saw pictures of the footswitch for that amp and it may be too small to include a 9 volt battery, but perhaps there is room for an N-Cell holder and battery.

Or maybe a 9V source from the pedal supply?
It wouldn't take much to run an LED for quite a while! (I have helped the kids "decorate" their Halloween costumes and have noticed days later that they are still lit with a CR2032!)

Quote:

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Originally Posted by Bill Moore

Or maybe a 9V source from the pedal supply?
It wouldn't take much to run an LED for quite a while! (I have helped the kids "decorate" their Halloween costumes and have noticed days later that they are still lit with a CR2032!)

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The footswitch for that amp looks like this, so there is no 9V source. But you could gut a non-working guitar pedal and use the existing 9V battery holder, LED, and install a double pole switch in it.

https://i.imgur.com/H66m9YI.jpg

I'm assuming that most use a pedal power supply, (I do), plenty of room on that switch for a 9v jack.