Sunflower: LED remains lit in bypass

[greggerypeccary]

Everything seems to be working properly except the indicator LED remains lit when the effect is bypassed and connected to power(regular Boss PSA). I used the 3PDT breakout board and it is oriented correctly(pedalpcb.com text face up, switch pins horizontal). Any ideas?

Thanks!

 

[greggerypeccary]

Here's a gutshot. It's a bit ugly with many parts salvaged from other things. OC77 transistors.

 

[Nostradoomus]

There appears to be a stray clipping between your SW and OUT pads. Get the toothbrush and Isopropyl alcohol out!

 

[greggerypeccary]

Hey, thanks for replying. I tested for continuity between the SW and OUT pads and there is none

I also placed a plastic dust cover on the sundial pot to prevent anything shorting against its casing. No change! I'm sure its just some obvious thing I missed!

 

[Nostradoomus]

It’s either your switch, 4k7 resistor, LED or wiring that’s amiss. There’s nothing else in the path haha...I would recommend you build a test box, it helps to identify when you’ve got a bad switch much quicker!

 

[Chuck D. Bones]

Can you tell us why the trimpots are on a separate board?

 

[chongmagic]

Can you tell us why the trimpots are on a separate board?

I was thinking the same thing.

 

[phi1]

Hey, thanks for replying. I tested for continuity between the SW and OUT pads and there is none

If there's no continuity between SW and OUT, the LED shouldn't be on. If there was a connection directly from the LED cathode to ground, bypassing the 4k7 resistor, then your LED would burn up.

Could you try measuring the resistance between SW and OUT? (in bypass mode when the LED is supposed to be off). Maybe there is a solder bridge that is passing current, but providing enough resistance that your DMM continuity setting doesn't register it. To that end, there also looks like something fishy on the right leg of the 4k7 resistor.

The portion of the circuit that lights up the LED is very simple, so you can study it and check the connections one by one. You could always build this portion off board if you can't solve it (it's just a resistor and some wires).

 

[greggerypeccary]

I swapped out the LED and now it works! I was pretty sure there were no bridges between the LED pads but...

The separate board is cuz my trimpots were too big for the PCB.

 

[Chuck D. Bones]

Purty! Proper control setting are critical and I see you found the correct setting for this pedal!

You must have fixed a solder bridge in the process of replacing the LED because there is no way an LED can illuminate itself.