LED is on when GGG Tube Screamer is switched off

[skrapasor]

I built a GGG Tube Screamer using the ITS8 complete kit and I've checked my wires and I'm pretty sure they are right, but the LED is on when the pedal is off, and that's not right. It also seems to drain way too much power out of my battery, like within a couple weeks of using it a few hours a week. Here is a link to the .pdf files that might be helpful to look at: http://www.generalguitargadgets.com/index.php?option=com_content&task=view&id=82&Itemid=26.

[moose23]

Can you post a picture of your pedal and wiring?

[skrapasor]

Sorry! I guess I just got distracted from this for a while. I got a Big Muff Pi kit recently and I want to build that so I figured now would be a good time to fix this Tube Screamer. But really, it hopefully shouldn't matter to anyone that I'm replying so late. And I promise, I did my best taking this picture with this crappy camera.



Is it possible that the switch is turned around? I realize you might not be able to see all the connections, so if you have any thoughts about what could possibly be wrong just ask me and I will check it closely.

[skrapasor]

And I followed this layout diagram: http://www.generalguitargadgets.com/pdf/ggg_its8_lo.pdf

[jkokura]

this would probably be a wiring issue. I don't see how something on the board would be giving you a problem. If it were my pedal, I'd be cutting all the wires and redoing the wiring, but you might be able to figure out what you did wrong and just be able to fix it.

Jacob

[petemoore]

I built a GGG Tube Screamer using the ITS8 complete kit and I've checked my wires and I'm pretty sure they are right, but the LED is on when the pedal is off, and that's not right.
  Start testing. The switch works.
  Looking at the LED circuit:
  power supply *
  LED *
  Current limiting resistor *
  Switch...Use the DMM to find 2 lugs on the switch which switch when.
  The LED is working, find the 'spare' pole and throw that disconnect when the Ckt. is in bypass mode, connects when in the signal chain, put the LED circuit through there.
  It also seems to drain way too much power out of my battery, like within a couple weeks of using it a few hours a week.
  Dunno how strange that really sounds, the current Ma. draw can be measured, put your DMM in the power supply circuit, between a battery and battery clip, measure the ma. going through the DMM.
  Determine the LED current draw, IIRC the TS circuit draws less current than the LED circuit.

[skrapasor]

I don't see how that would help since I would just do all the wires the same way. Indeed I believe the wiring to be the problem. The only reason there is a picture of the board is because it is right in the middle of all the wiring. One thing I didn't think of when building it from what I remember is the orientation of the switch. I'm guessing the switch is rotated or something so the wires are on the wrong lugs. How do you know what direction to orient it?

This was in reply to jkokura.

[petemoore]

 Me? I look through 3 left-row lug eyelets, they are throw>pole>throw.
There are 2 addition rows of lugs through which photons can travel [you can poke a resistor lead through all three lug eyelets instead if desired].
Now you have a row on the right, a row between, a row on the left.
Each row = 1 x SPDT switch [throw>pole>throw].
SPDT= 1 pole, and a throw on each side.
  Connect the DMM to the pole, find a throw that is connected to the pole, inline with the through-eyelet sighting, one throw connects, the other doesn't.
  These connection conditions reverse when you hit the switch [the other connects, the one is disconnected]. 
  Verify with DMM that each separate spdt [within the 3PDT] has a pole and two throws, the two throws alternate connecting to their pole.

[skrapasor]

Thanks for the help but I'm very inexperienced and so I'm not quite understanding all of this. What is the point of the three poles? Are they all really used? And the two throws on each pole are just for connecting and disconnecting?

[Quackzed]

well, think of each pole as an arm that is connecting to  either the top throw or the bottom throw . evey time you stomp the switch, the pole connects to the other throw...
and you need them all when wiring for true bypass in most pedals

the 2 outer poles are for the input signal and output signal
and the middle one for the led.

one side of the led is usually wired to the middle pole
and one of the throws is connected to ground(top) and the other is connected to nothing.(bottom)
so in one stomp the led lights (connected to the grounded throw)
and after another stomp the led doesnt(connected to nothing throw)

if the led is working opposite, you could find the middle throw (top or bottom lug on the middle vertical row)that is connected to ground and , remove the ground wire from it and move the ground to the other throw, that was unconnected to ground before...that is if all else works ok, and the only issue is the led is working opposite than desired.

so in short..
1. the led is connected to the center pole.
2. the lug above it is connected to ground and the lug below it is connected to nothing (or vise versa)
3. remove the ground from where it is now, above or below the center lug
4. connect it to the opposite lug (above or below) from where it was before.

[skrapasor]

Did any of you look at the layout diagram? From what I now understand, wiring it like the diagram should work. What do you guys think?

[skrapasor]

I'm assuming that in one position, all the poles are connected to the top throws, and in the other position, all the poles are connected to the bottom throws. Is that right?

[fpaul]

Yes

[skrapasor]

Okay I don't understand the suggestions then. If you can't tell from the picture, and I don't blame you, I have the switch wired exactly as it is in the layout diagram. The input to the circuit, the LED lead, and the output are all wired to throws on the bottom of the switch. Therefore, when the switch is turned on, the signal should go through the circuit and the battery should make the LED glow. What could be wrong? I don't understand what checking the switch will do. Can't we assume the switch functions probably?

[Quackzed]

it does appear to be wired correctly, weird. could the led be backwards?!

[jkokura]

Yeah, looking at the switch it seems like that's wired right, or at least you have it orientated right. However, I can't clearly see the power wiring and the LED wiring. Could you post a link to the wiring diagram you're using? Unless you know you want to start over on from scratch on your wiring like I would, I then recommend that you carefully check the diagram you followed (I'm assuming you followed one) against your job. If anything is wrong, fix it and then start over on your check. Once you've done a complete check and everything seems right, check again. Hopefully it'll be working then.

However, if it isn't working it may be that the diagram you're following is faulty. I use either the 'offboard wiring' from Tonepad or this wiring from Gaussmarkov's site:

http://gaussmarkov.net/wordpress/thoughts/wiring-up-a-1590b/#more-116

Jacob

P.s... welcome to the world of debugging. I hate it the most, but it's very rewarding to complete a pedal that was initially not working. Almost as rewarding as firing up a pedal with no debugging (only done that once).

[jsleep]

If the short lead of the LED is shorting against the enclosure it would cause this problem.  Any short to ground in the wiring from the short lead of the LED would cause your problem.  If the LED is wired backwards, it wouldn't work at all, so you know that's not your problem.   There is a rare possibility that the footswitch is broken on the middle set of poles only.  Easy enough to test that and make sure it's working with a ohmeter.  Otherwise, it's gotta be a wiring problem somewhere.  I can't see the DC jack wiring very well.  Your battery problem is usally also caused by a wiring problem causing the ground to be connected to the circuit even when the input jack is removed.  I guess I should have asked if you are removing your input jack when not in use?

Unrelated to your problem:  It looks like you have a bad solder joint on the input jack /black battery snap wire.

JD

[skrapasor]

I posted the wiring diagram already but it's no problem: http://www.generalguitargadgets.com/pdf/ggg_its8_lo.pdf

And I've checked it like ten times now and I'm almost 100% sure it matches the diagram. I don't think it would make sense for me to just redo all the wiring since I would do it the same way. The GGG website even has a list of ways to wire the input, output, and LED and I check this against one of them and they are identical except they use different columns of SPDTs.

And jsleep, your ideas seem quite plausible I will definitely check them later. How exactly do you test a switch? Should I put an LED in the circuit so I know when it is and isn't closed?

[skrapasor]

I've made a discovery. When I touch the end of the LED with the black wire on it (I think that's the negative end) to the tip of the input jack, when the switch is turned on, the LED glows brightly. This is way brighter than when it is supposed to be off but still glowing. I'm thinking the only problem then, is when the pedal is on. There is probably some broken connection or something somewhere. Or maybe the switch is messed up. I'll investigate further.

[skrapasor]

Okay, I've investigated! When I take an alligator clip from the end of the LED attached to the black wire to the middle pole, it lights. When I connect it to the bottom throw when the switch is on or off it doesn't light. Doesn't that mean the switch is screwed up? Because the switch at some point should be touching the pole to the throw.