2nd Gen Build

[dbharris]

This one made me laugh a bit. I built the foot switch today and went downstairs to test it. Foot switch turns the amp pilot light on or off without changing the channel. The panel channel switch does work fine.

I'll have to pull the chassis and see where I connected things on the relay power board, which I am also using to power the pilot light LED.

-Dan

[Raoul Duke]

Sounds like something I’d do, lol.

I’m sure you’ll straighten it out quickly Dan!

[dbharris]

I could use some ideas here, there must be something very obvious that I am missing.

A few notes:
I am not using a voltage regulator.

Using half of the relay transformer secondary was giving about 9.5 volts DC at the relay supply. Using the full secondary was giving about 18.3 volts DC. Both seem to function fine with no foot switch connected.

I got the pilot light off of Amazon, the data sheet is about physical dimensions. I couldn't determine if it had a CLR built in or not. I am using the 2 CLRs on the relay board for the pilot light and the relay +. I have a brown wire connected to the top of those resistors (right side of the board) that runs to the XLR jack for the foot switch cable and then I have a CLR inside the foot switch for its LED. I did a similar type of arrangement for my #102 and it works great.

I have a white wire from the relay function to the middle lug of the panel switch. Blue wire runs from the bottom lug directly to the XLR jack.

I have tested continuity between everywhere I can think of and it all seems normal, with and without the foot switch. If the chassis channel switch is set to pedal and I activate the foot switch, the foot switch led lights up for a brief moment only, the pilot light LED turns off and the channel does not change. Click the switch again and the pilot is back on, still on clean.

Measuring voltage on the relay without the foot switch connected seems normal too. A slight drop depending on the state of the relay.

With the foot switch connected, the voltage drops to a few hundred mV. Seems like this is the only thing not acting normal. Since it is not 0v, I am assuming it is not a short to ground. But maybe something using a lot of current and pulling the voltage down too far?

Any help is appreciated!

Thanks,

Dan

[GAStan]

With the foot switch connected, the voltage drops to a few hundred mV. Seems like this is the only thing not acting normal. Since it is not 0v, I am assuming it is not a short to ground. But maybe something using a lot of current and pulling the voltage down too far?

Any help is appreciated!

Thanks,

Dan

The combined wire, switch and connector contact resistances might be enough to give you this small voltage. It sounds like you are shorting the +DC to ground. Try drawing the circuit as it actually is, not just how you think it is. Actually trace it out physically as you draw it, don't go from memory. This can help make any errors more evident.

[dbharris]

With the foot switch connected, the voltage drops to a few hundred mV. Seems like this is the only thing not acting normal. Since it is not 0v, I am assuming it is not a short to ground. But maybe something using a lot of current and pulling the voltage down too far?

Any help is appreciated!

Thanks,

Dan

The combined wire, switch and connector contact resistances might be enough to give you this small voltage. It sounds like you are shorting the +DC to ground. Try drawing the circuit as it actually is, not just how you think it is. Actually trace it out physically as you draw it, don't go from memory. This can help make any errors more evident.

Glenn, thanks for the response! I was going over everything again with a fine attention to detail and found my mistake. Having never worked with these XLR jacks before, I did not know that the pinout is different on the male and female jacks from how they appear on the solder side. I was using the bottom lug for ground, which was consistent but the lug to the right of it looking inside the chassis is connected to the lug on the left side inside the pedal.

Anyways, just got it working for real and nobody (except my wife) will be happier than me to call this amp completed lol!

Here is the picture tax:

PXL_20240708_001943797.jpg

PXL_20240708_001952363.jpg

PXL_20240708_002201043.jpg

Thanks All!

-Dan

[GAStan]

Dan, glad you got it going. Great looking build!!!