# Magnetron Delay LED issues



## sodapop808 (Dec 21, 2020)

Hey everyone!
I wired up a magnetron delay today.  When engaged, the effect works properly but LED 1 (that I am assuming is supposed to pulse in time with the effect?) stays lit solid and LED 2 (that should be the bypass indicator) is also lit.  
When disengaged, however, LED 2 stays lit.

The only changes I made to the circuit where I changed R27 and R28 to 10K resistors because I am using blue LEDs and I wanted to tame them a little bit.  Did I incorrectly assume that those were the CLRs and accidentally screw something else up by changing those values?  

I've tested with a DMM and get readings from input to switch  and from  output to switch and have tested the switch itself and get continuity through it through the poles.

The only thing I haven't tried is unsoldering the LEDs and testing to see if somehow it's just labeled backwards or something I know I used anode to anode but maybe something was weird.

I thought I'd ask here first before I unsoldered the LEDs.


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## Mcknib (Dec 22, 2020)

First I'd check your LED pins are both grounded and not shorting on anything like metal bezels

LED 2 is the LFO indicator in the schematic although not in the BOM where it says LED1 easy enough to confirm check which CLR has continuity with depth lug 2

10K for a standard blue LED I'd say is too high the ones I use you'd barely see with that much resistance and less current

Looking at the schematic I'd think it's the LFO LED that would remain on it looks to me that as soon as you apply power the LFO LED would come on regardless of switch position, perhaps to allow you to set the speed before engaging?

I'd go with the 4K7s unless you're using super bright LEDs especially for the LFO LED it's the op amp voltage which drives that which'll be VCC


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## Danbieranowski (Dec 22, 2020)

The LED for the modulation speed should only turn on as you increase the depth, and should increase in brightness as the depth knob increases. Just wanted to drop this note in here so the expected behavior is known.


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## Mcknib (Dec 22, 2020)

Does it come on as soon as you power the pedal up Dan? Looks like it with the ground not being switched but idk never built one


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## sodapop808 (Dec 22, 2020)

Ok!  I got it sorted!  Yes.  I had the LEDs in the enclosure based on the BOM numbers.  I assumed incorrectly the one at the top of the board was the one that pulsated with the speed of the LFO.  I also didn't realize it was tied to depth, so I turned that up an voila! All I had to do was rewire the wires to each of my LEDS to be longer and ran them under the board.  Now the orientation makes sense.
Thanks everyone.  Pedal sounds great!


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## Danbieranowski (Dec 23, 2020)

Mcknib said:


> Does it come on as soon as you power the pedal up Dan? Looks like it with the ground not being switched but idk never built one


The mod LED doesn’t turn on unless you turn up the depth. Looks like @sodapop808 figured it out. I did the EXACT same thing on my first Magnetron build and had to rerun my LED wires too. Good times!


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## oldacid (Nov 26, 2021)

I just built the Magnetron and the mod LED isn't doing anything-in the most recent version drill template there actually is no hole for the second LED. Anyone know if this has been removed from the circuit? There's still pads on the board for it, and the LED works when I test it with multimeter. I feel like I'm missing some information here.


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## music6000 (Nov 26, 2021)

oldacid said:


> I just built the Magnetron and the mod LED isn't doing anything-in the most recent version drill template there actually is no hole for the second LED. Anyone know if this has been removed from the circuit? There's still pads on the board for it, and the LED works when I test it with multimeter. I feel like I'm missing some information here.


Is the Led Anode leg on the right, Cathode leg (Flat spot on LED Base) on the left?
It is only effective if the Depth knob is cranked up.


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## oldacid (Nov 26, 2021)

Nevermind....Pin 4 of IC2 had a damaged pad from overly aggressive wicking to fix a previous mistake. This was breaking the ground path for the cathode of LED 2. Soldered on a little jumper wire and now it works.


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