Author Topic: I tried building a test box. It doesn't work.  (Read 685 times)

harryklippton

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I tried building a test box. It doesn't work.
« on: August 26, 2019, 11:38:46 AM »
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!

jimilee

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Re: I tried building a test box. It doesn't work.
« Reply #1 on: August 26, 2019, 11:56:27 AM »
Itís hard to see whatís what, is your ground on the dc jack wired to the + on the PCB?


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gordo

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Re: I tried building a test box. It doesn't work.
« Reply #2 on: August 26, 2019, 12:12:56 PM »
on a zoom in it also looks like the hot and ground is touching between the 2 1/4" jacks.

gordo

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Re: I tried building a test box. It doesn't work.
« Reply #3 on: August 26, 2019, 12:13:37 PM »
Plus I had to giggle at the prospect of troubleshooting a troubleshooting box :-)

harryklippton

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Re: I tried building a test box. It doesn't work.
« Reply #4 on: August 26, 2019, 05:31:11 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

somnif

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Re: I tried building a test box. It doesn't work.
« Reply #5 on: August 26, 2019, 05:35:31 PM »
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.

harryklippton

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Re: I tried building a test box. It doesn't work.
« Reply #6 on: August 26, 2019, 05:36:36 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?

harryklippton

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Re: I tried building a test box. It doesn't work.
« Reply #7 on: August 26, 2019, 05:37:31 PM »
Also I'm never sure which lugs to use on the 9v jack. Can someone straighten me out on that?

somnif

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Re: I tried building a test box. It doesn't work.
« Reply #8 on: August 26, 2019, 06:06:06 PM »
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/


harryklippton

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Re: I tried building a test box. It doesn't work.
« Reply #9 on: August 26, 2019, 06:12:13 PM »
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.

harryklippton

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Re: I tried building a test box. It doesn't work.
« Reply #10 on: August 26, 2019, 06:49:25 PM »
Ok,  led works now. That's progess!

harryklippton

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Re: I tried building a test box. It doesn't work.
« Reply #11 on: August 27, 2019, 12:03:15 PM »
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.

mjg

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Re: I tried building a test box. It doesn't work.
« Reply #12 on: August 27, 2019, 04:09:52 PM »
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.

jimilee

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Re: I tried building a test box. It doesn't work.
« Reply #13 on: August 27, 2019, 06:13:10 PM »
Can you connect the black in and the yellow out together and get sound? Thatís the first thing I believe. Test it without a board.


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harryklippton

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Re: I tried building a test box. It doesn't work.
« Reply #14 on: August 27, 2019, 06:24:02 PM »
Can you connect the black in and the yellow out together and get sound? Thatís 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!