Battery/DC problem, re: GGG wiring diagram

[djwackfriz]

Hello all,

I'm finishing up my Bazz Fuss pedal, and everything works great except for the battery power. When plugged into DC, with the battery also connected, the pedal runs no problem, and the LED lights. When I have just the battery connected, no luck. I am using a stero input, with the battery negative on the ring and the board ground on the sleeve, as the GGG diagram on wiring suggests. This is actually the second pedal that I'm having this problem with...

can anyone please suggest a diagram or wiring scheme for battery AND DC that definitely works, so I can double check?

[Hanglow]

check the dc jack wiring - the battery +ve must go to the inside lug and the board +ve must be connected to the outside lug. If these are the wrong way round then what you have just described will happen.

http://www.generalguitargadgets.com/pdf/ggg_bmp_wiring.pdf   just picked a ggg project at random, this is correct

[djwackfriz]

Thanks... I gave it a shot, but still no luck. I'm gonna play around with my grounding, maybe there's something wrong.

The main problem is that I have an LED to incorporate, but nowhere on the PCB for it, so it has to be offboard. Right now, I have it entering the circuit at the same point as the top lug of the dc jack (the positive)... hmmmm

[djwackfriz]

OK, I started from scratch and now have the offboard wiring set up exactly like the tonepad "Wiring 5" diagram.    (  http://tonepad.com/getFile.asp?id=76   ) Everything from the switch to the star grounding is the same.

Same thing as before, pedal works when plugged into DC, but not with the battery. I checked the battery voltage, getting 8.6V... Any ideas?

I'm at wits end here, it's the last kink before I finish my very first start-to-finish pedal!!! I'm psyched! Thanks so much to everyone on this board for their help, I'm hooked!

[5thumbs]

I've wired several projects according to the 'Wiring 5' diagram, so I can personally vouch for that configuration as working.

Since it's kind of hard to assist much without more information, you might want to check out the sticky topic 'DEBUGGING - What to do when it doesn't work' here: http://www.diystompboxes.com/smfforum/index.php?topic=29816.0.  If you collect the information as directed in that topic, then post the results here, it will allow others to assist you more readily.

As a parting shot-in-the-dark, the DC power adapter isn't dependent upon the ring ground on the input jack to operate; the 9V battery snap is dependent upon that arrangement to properly connect to ground when a plug is inserted in the input jack.  Double-check your ground wires on the ring and sleeve lugs of the input jack to ensure they are wired precisely as indicated in the 'Wiring 5' diagram.  If those are correct and you've got the +9v side of the power connector wired as suggested by Hanglow (and the 'Wiring 5' diagram), you'll need to give the group some more info so we can help you further.

[djwackfriz]

OK, here are some voltages... I think the circuit looks fine, which leads me to think that I screwed up something offboard. FWIW, the circuit works fine with DC power, it's a nice bass fuzz. It just this dang battery! A funny thing happened while I was collecting these voltages - my multimeter lead grazed the ring and sleeve of the input jack, joining them, and the LED lit up! I tried it again after pulling my guitar cable out of the input, and it still did it!!! which I think means that power CAN get to the circuit by way of battery, but something in the input jack grounding is fudging it up.... maybe it's not engaging when I plug a cord in?   HELP!!!

Input Jack Ring ---> Battery Negative
Input Jack Tip ---> Input lead to 3PDT switch
Input Jack Sleeve ---> Ground leads for DC Jack, Board, Output Jack and 3PDT switch (this feels like a lot of wires to be connected in one place, but the diagram said to do it for star ground)
Battery voltage: 9.14V

input jack tip:  4.06V
Voltage at the circuit board end of the red battery lead = 9.14
Voltage at the circuit board end of the black battery lead = -7.96

Q1
C = 8.05
B = 8.07
E = 8.95

Q2
C= 8.07
B= 7.84
E= 8.95

D1
A = 7.83
K = 8.95

D2
A = 8.95
K = 8.57

D3
A = 8.57
K = 8.20

D4
A = 8.20
K = 7.84

if you need cap or resistor voltages I can get them! Thanks for any help!

[djwackfriz]

You know, I'm thinking about this... is it possible to burn out an input jack? I've unsoldered and resoldered on it a few times, but since it has no moving or electronic parts I figured it would be tough to destroy...

anyway, bump-a-roo!

[dxm1]

A funny thing happened while I was collecting these voltages - my multimeter lead grazed the ring and sleeve of the input jack, joining them, and the LED lit up! I tried it again after pulling my guitar cable out of the input, and it still did it!!! which I think means that power CAN get to the circuit by way of battery, but something in the input jack grounding is fudging it up.... maybe it's not engaging when I plug a cord in?   HELP!!!

This is more than likely your sole problem - the negative battery wire (which should be connected to the RING terminal) is not getting grounded to the SLEEVE terminal when you plug a cable in. You are using a MONO cable for input, right?

TRS jacks are usually pretty robust, but can be bent out of shape or defective from the factory. If you have another stereo TRS jack, solder that up and test it. If not, you can use a stereo 1/4" plug and test for continuity on the RING terminal.

Also, is this a Cliff/ReAN style of jack? They provide two seperate solder lugs for each contact, one set being OPENED when a plug is installed...

[djwackfriz]

A funny thing happened while I was collecting these voltages - my multimeter lead grazed the ring and sleeve of the input jack, joining them, and the LED lit up! I tried it again after pulling my guitar cable out of the input, and it still did it!!! which I think means that power CAN get to the circuit by way of battery, but something in the input jack grounding is fudging it up.... maybe it's not engaging when I plug a cord in?   HELP!!!

This is more than likely your sole problem - the negative battery wire (which should be connected to the RING terminal) is not getting grounded to the SLEEVE terminal when you plug a cable in. You are using a MONO cable for input, right?

TRS jacks are usually pretty robust, but can be bent out of shape or defective from the factory. If you have another stereo TRS jack, solder that up and test it. If not, you can use a stereo 1/4" plug and test for continuity on the RING terminal.

Also, is this a Cliff/ReAN style of jack? They provide two seperate solder lugs for each contact, one set being OPENED when a plug is installed...

I'm going to try this out soon. I'm actually using a Stereo jack for input, so I can switch between battery and wall wart. It's just a Switchcraft stereo jack, from Aron.

I would not be at all surprised if I torched it somehow, or screwed something out. I do that a lot!

Thanks for the suggestions, I'll let you know the results.

[djwackfriz]

Whoa! This is nuts!

I switched to brand new stereo jack for the input, connected everything same as before (Input to Tip, Battery Negative to ring, all grounds to sleeve), and now my LED comes on when JUST THE TIP of the speaker cable is inserted, in other words when the pointed part of the speaker cable comes in contact with the first 2mm of the ring. Then, once I push the cord all the way in, the connection breaks, and there's no signal. SO WEIRD@!

I'm gonna try with some different cables... Any crackpot ideas are welcome!

[djwackfriz]

AHA!

Who knew that a stereo plug would not work the same as a mono plug? I tried a different cable and this baby WORKS!!!!

FIRST BUILD COMPLETE! I'm gonna have a beer.

Thank so much for all the help everybody! I'm so psyched right now, this is the first thing I've ever built from scratch in my life that really WORKS!