Hey guys,
I've just started my first build since a butchered attempt a few years ago.
I'm doing the woolly mammoth clone (http://3.bp.blogspot.com/--u0tgh_NBQw/T5vxEP7Fp7I/AAAAAAAABYE/klCZpa0-AF4/s1600/ZVex+Woolly+Mammoth+-+smallest.png)
My question is where do the ground wires go? What is the principle behind the ground wires (do they all go to the outputs in whatever order? Do they all go to the board?)
I've tried wiring this up, improvised out of impatience and found myself completely lost.
I'd like to understand how to get this to work so I know for future builds, but if anyone has an example of it correctly wired off board that would be greatly appreciated too.
Welcome to the forum!
The concept of "ground" is very important, and can be complex if we were to cover it all in one sitting. So, for now, here is the brief version:
Everything labeled "ground" gets connected to the negative terminal of your power source.
Keep asking questions until you understand all that you want to understand.
In small audio, "ground" mostly means "common". Half of all wires end up connected together, "common". This *includes* input and output jack shells, often one Power connection. We work high-gain audio inside metal boxes, and the box is tied to common.
Utility power wall-outlet work has other implications. But in Pedal-World, if your main amplifier is correctly grounded (3-pin plug, working) then the pedals get that ground through the audio cords.
Hey, thanks. I'm glad to be getting involved!
Does everything need to be connected "directly" to the negative terminal, or is it all connected to a sort of loop that works its way back to the negative terminal? And I'm assuming the negative terminal goes out through the cable and out to the Mains?
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Welcome Cmwm,
In the end, they all go to the negative terminal (UNLESS it's a positive ground circuit ... far less common, but they are out there for sure, some fuzzes and so on). The route they take there is debatable, sometimes.
It's mostly agreed that all the grounds on the circuit board should go to 1 spot on it, which then can go off to the input jack's switch lug...then, the other switch lug goes to battery ground. This is how the input plug 'turns on' the pedal, and why you need to pull it out when you're done or the battery eventually goes dead. The method of running all board grounds to one place is called 'star grounding'; I'm sure there are whole articles on it, on the internet.
So, it's a 'method', but not a LOOP...since a real ground loop is BAD! (lol) Keeping it direct and as short as you can would be the idea...avoids noise, picking up RF and general crappy performance.
Take a look at some of these wiring diagrams (and keep this file for your use!), they will make the idea clear, I'm sure. http://www.generalguitargadgets.com/how-to-build-it/technical-help/switching-and-wiring/bypass-sw-options/ (http://www.generalguitargadgets.com/how-to-build-it/technical-help/switching-and-wiring/bypass-sw-options/)
Is a stereo jack necessary for a circuit to work? I've used a mono jack for the input though I'm sure that's not the only issue with my wiring hahaha
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Quote from: Cmwm on March 08, 2018, 02:36:52 AM
Is a stereo jack necessary for a circuit to work?
Strictly speaking, No..!!
Ring (middle) lug of stereo jack acts as a ground connection "switch" (establishes continuity via plug body) so pedal isn't powered when unplugged..
(electrons from negative pole of battery or power supply can't find path to proceed to positive pole..)
You can wire it any way that makes sense, and the jack is just to turn it on or off, as stated.
The stomp switch and LED are also only for 'when in use'....when I build a circuit, to test that it works I always connect a mono jack to input and output, with the sleeves connected to ground with jumper wires. Sometimes the jack grounds are just connected to each other, with one to ground. This often means that all my ground wires meet at the ground wire coming from the PCB. This is fine to test a circuit. It may be a little noisy, depending what the circuit is. By testing the PCB this way, I know that any future mistake will be caused by the switch or jack wiring, 99.99% of the time (not 100% because the board COULD be damaged while handling, but that's not likely).
When laying out the PCB, one wants to make each stage's ground go to a board ground point (to avoid ground loops..this is 'star grounding'). Then, when it's time to install the jacks and switch, LED etc., and put it in the enclosure, one of the common wiring schemes I linked to can be used. But to test the circuit, as long as the grounds are connected, you are good to go! Complete the path, physics will do the rest :)
Quote from: GibsonGM on March 08, 2018, 07:57:07 AM
when I build a circuit, to test that it works I always connect a mono jack to input and output, with the sleeves connected to ground with jumper wires.
Can't recall the times troubleshooting a "dead" pedal with unplugged stereo input jack ... :icon_redface:
Quote from: antonis on March 08, 2018, 08:43:27 AM
Quote from: GibsonGM on March 08, 2018, 07:57:07 AM
when I build a circuit, to test that it works I always connect a mono jack to input and output, with the sleeves connected to ground with jumper wires.
Can't recall the times troubleshooting a "dead" pedal with unplugged stereo input jack ... :icon_redface:
It happens to everyone! Or not connected to the amp ;)
Quote from: GibsonGM on March 08, 2018, 10:22:09 AM
It happens to everyone! Or not connected to the amp ;)
Yessir. PCB wired up and guitar and amp In/Out reversed. "Why isn't this working?"
Quote from: GibsonGM on March 08, 2018, 10:22:09 AM
Or not connected to the amp ;)
Perhaps that's the ultimate lever of troubleshooting..
(last step before transcendental meditation..)
Back once again!
Tried to guess my way to a wiring. Here's a rough drawing of how I've currently got the off board wiring. It's not working.
(https://uploads.tapatalk-cdn.com/20180313/b4a41ee63f55de091d64824348f31278.jpg)
If there are no glaring issues with what I've done then I'll move on to reflowing the board as that seems to be the #1 suggestion.
Any ideas and suggestions welcome, trying to learn so I'm open to scrutiny.
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Wiring looks OK (assuming you chose the right lugs on the jacks). Time for photos of your board.
And the right plugs on the jacks..
Cool I'll get some photos posted once I get home. Thanks for your help guys
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Here we go guys,
(https://i.imgur.com/nyScT5h.jpg)
(https://i.imgur.com/e7CILHr.jpg)
All the Cooper traces have no connections over, checked and double checked.
Had difficulties reading the colours of each resistor so used a multimeter and had each component organised and each component was called for, its possible one reading was close to another reading and they "overlapped" and ended up swapped.
I can add photos off the pots but it's difficult to get a photo of it all making sense
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It's hard to tell since the second image is pretty blurry, but are you ABSOLUTELY SURE there are no solder bridges between tracks? Because (again could be the blurriness) but I swear I see some in there.
I think that's flux reflecting light, to be sure I've used a scalpel to score between them and get rid of anything.
Noticed some shoddy solder on the output jack, waiting for the soldering iron to warm up so stay tuned!
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Still silent.
Any good resources for troubleshooting with a multimeter (if that's the logical next step)
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Alright, well if you promise there's no solder bridges let's move on to voltages. Measure the voltage on all three legs of both transistors, and that should give us a good idea what's happening. Also measure your battery voltage so we have a reference of what voltage to expect where.
Aside from voltages I would also like to recommend an audio probe. Mine has helped me trace the problem on dozens of builds.
The region around 2 orange & purple wires is VERY suspicious..!! :icon_wink:
Should I measure each individual leg or the entire transistor?
Not sure how to go about the individual leg way.
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Black lead on GND and Red lead on any individual leg..
(or vice versa, ignoring the minus sign, but maintain the same leads orientation for all measurements..)
Quote from: antonis on March 16, 2018, 07:23:00 AM
The region around 2 orange & purple wires is VERY suspicious..!! :icon_wink:
Hahaha yeah, it looked it to me. Nothing is touching. I'll do some cleaning up and see if that works
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Power is being drawn up until the first transistor at which reads 0.
Fried transistor?
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Quote from: Cmwm on March 16, 2018, 10:12:18 AM
Power is being drawn up until the first transistor at which reads 0.
All three legs?
Yes, everything after that is reading at 0.
Battery is checking at 9.7, that's present up until I check the first transistor.
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Mmkay, well that's a pretty good indication of a problem. Are you getting 9V on the top leg of the 51k and 20k resistors that go between the battery and the collectors of the two resistors? That would be the first place I would check. If your transistors aren't getting any juice they aren't going to work very well :P