Hi, I tried building a test box and it doesn't work. I'm using a Rullywow 3PDT board for my switch. I thought I had everything hooked up correctly, but I guess not. Here's what I know so far:
1. The LED never lights up in either switch position.
2. I don't know what value to use for the CLR resistor. I think I used a 100ohm resistor.
3. I get 9v across the barrel jack lugs, on the pcb connection at the other end of the wires connected to the barrel jack, and at the end of the alligator clips going to the circuit I wish to test.
4. In one switch position, I get signal to my amp. In the other position, no signal.
I hope I made a silly goof here. Any help would be greatly appreciated. Thanks!
It's hard to see what's what, is your ground on the dc jack wired to the + on the PCB?
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on a zoom in it also looks like the hot and ground is touching between the 2 1/4" jacks.
Plus I had to giggle at the prospect of troubleshooting a troubleshooting box :-)
Quote from: gordo on August 26, 2019, 06:13:37 PM
Plus I had to giggle at the prospect of troubleshooting a troubleshooting box :-)
I thought the same thing before posting.
I double checked the aforementioned items. The in and out jack connections aren't touching. I reoriented each and tightened the nuts to avoid this calamity.
The hot and ground connections from the barrel jack are hooked up to the board correctly. The wires are slightly crossed under the board making them look backwards.
I'm gonna go through and double check all my connections again, plus look for bad solder joints too
100 ohm is a bit low for 9V through an LED. That would move 90mA and .81 watts of power. Its entirely possible you fried the LED I'm afraid.
Quote from: somnif on August 26, 2019, 11:35:31 PM
100 ohm is a bit low for 9V through an LED. That would move 90mA and .81 amps of current. Its entirely possible you fried the LED I'm afraid.
Oh shoot. What value do you suggest?
Also I'm never sure which lugs to use on the 9v jack. Can someone straighten me out on that?
For CLRs (current limiting resistors) it varies depending on what type of LED.
Superbright water-clear white or blue, I can go up to 30k to tame it (want an indicator, not a searchlight).
For old style diffuse reds, as low as 330ohm (assuming I'm using normal 1/4W resistors).
4.7k is seen as the "default" value on most PCBs you buy, for what that's worth. For what appears to be a diffuse green like you have, 1k would probably work a little better.
For the power jack situation I direct you to Beavis: http://beavisaudio.com/techpages/PedalPower/
Thanks somnif.
I'm gonna swap out the LED and the resistor and see what happens.
I also tried connecting my in and out alligator clips and I get signal passing with the switch in either position. With a board connected, i get clear signal in one position (same as if i plug straight into my amp) and very very faint signal in the other position.
Ok, led works now. That's progess!
The LED is sort of on sometimes and then comes on brighter when I switch the switch. I switched to a blue LED cuz that's what I had, and swapped the current limiter resistor to a 4.7k
I tried hard wiring the circuit I'm trying to test to the 3pdt board but got the same result.
I don't know what else to look for or try at this point besides dismantling this and starting over.
This is just a suggestion, I may be way off. Have you checked that the 3PDT switch has been inserted correctly in the board? If you had it rotated 90 degrees and soldered it in that way, it would be behaving in strange ways.
I think the way you have it is probably fine, but might be worth double checking that in the build doc.
Can you connect the black in and the yellow out together and get sound? That's the first thing I believe. Test it without a board.
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Quote from: jimilee on August 28, 2019, 12:13:10 AM
Can you connect the black in and the yellow out together and get sound? That's the first thing I believe. Test it without a board.
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Yes I get sound though when I connect black in and yellow out without a board attached!
Well, the test rig works, and whatever you have hooked to it needs to be trouble shot(shooted?)
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Quote from: jimilee on August 28, 2019, 12:47:06 AM
Well, the test rig works, and whatever you have hooked to it needs to be trouble shot(shooted?)
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I have two identical boards that behave the same way when connected. I'll have to check them over.
Ok I just learned a TON of stuff.
First, I goofed something on the circuit I was trying to test. I had 2 pots swapped on both boards I built. I just corrected one and stumbled on some other issues.
Two, the power source I was using is awful and makes everything howl. I will stop doing that to test pedals.
Three, the amp I was trying to use couldn't handle the pedal i was trying to test and was too noisy/instant feedback/ static noise
Four, my test box itself is noisy. I'm guessing this is because it's not grounded well enough.
Five, the circuit I built doesnt sound as good/loud as what its cloning. That may still be builder error though.
I'm about to correct its twin and see how it matches up.
Got my circuit working! There was a mistake in the build doc that left out a capacitor. I was reading the madbean tutorial in understanding pcb layouts and realized a cap was missing. I added the cap and BOOM circuit works just as expected.
Now my test box still has an issue. When the circuit is bypassed and power is connected, its VERY NOISY. Once I engage the circuit, the noise goes away. I tried multiple different power sources with basically the same result. What causes this?