Weird Vox V847 LED Problem

[Voxin]

Hello all, I'm new to this board and my knowledge of modding pedals and stuff is pretty limited, but I have a strange problem.  I just finished modding my wah with a Fulltone bypass switch and added an LED to it.  I used the instructions that are posted on the Stew Mac website.  The switch works fine, but the LED works only when no cables are plugged into it (I realized that it's not a huge problem because I've noticed that my Big Muff does the same thing...must be a true bypass thing) and as soon as I plug a cable into it or plug it into another pedal the LED stops working.  What have I done wrong here?  A pointer in the right direction would be a huge help!  Thanks. 

[captntasty]

Can't say exactly what's wrong but sounds like something is wired incorrectly.  Just to clarify, the effect works as it should but the LED works only when the cable is unplugged?  Which jack - input or output?  I'm assuming your input is used as the power switch... but it sounds like the LED is being disconnected when the plug is inserted but connected to power when the plug is removed, which is telling you the power is still on when it shouldn't be.  This is a bit farfetched but is the switch oriented correctly?  That is, when you installed it and wired it, was it oriented as in the lug map diagram on the bottom of the page at StewMac - as you're looking at the underside were the lugs oriented from side to side of the pedal or up and down... not probable that the pedal would work and not the LEDs, but what the hey.  Something is backwards.  Were the positive and negative leads wired in reverse - the positive will be the longer lead of the LED.  Just a few ideas... sometimes it's the no-brainer things that get you - and that is not to say you have no brains.  Sometimes in the heat and excitement of getting an effect fired up we miss small things.  Are the jacks wired correctly with respect to the switch and board?

Here's a link for a number different wiring schemes that have never failed me... There are a lot of options but the one's that will work in your situation are toward the bottom of the page - the 3PDT options (don't bother with the PNP option) http://www.generalguitargadgets.com/index.php?option=content&task=view&id=172&Itemid=200   One option is to rewire - unless some of the other folks have a better diagnosis... I am certainly not among the ranks of guru.

Welcome to the forum and let us know....

[Voxin]

I was just looking at the true bypass wiring diagram in the FAQ section and noticed that it is significantly different to how I have mine wired. This is the layout that I used (Diagram 2).[url]http://www.stewmac.com/shop/Electronics,_pickups/Components:_Switches_and_knobs/1/Fulltone_3PDT_Stomp_Switch/Instructions/I-1561.html#details[/url}  As for the LED, I added a wire going from the + of the battery clip and put a 1k resistor between that and lug #9.  Then on lug #8 of the switch I wired the LED and the had the - Cathode go to the ground like in the instructions.  The pedal works fine and lights up when on (without any cables plugged in), but the LED turns off as soon as I plug a cable into it.  I'm not too sure if I should wire it the way it looks like in the FAQ because the pedal does work fine...any help or attention to my errors would be greatly appreciated.

[Voxin]

Thanks for the reply captntasty, I really appreciate the comments.  Well, here's the story...the pedal lights up properly when the pedal is not plugged in (with the battery in of course).  I can get the LED to work when I plug a cable into both the input and output (to test the LED), but as soon as I have something else in the chain plugged in (ei: guitar or another pedal) the LED goes out.  I'm pretty sure that the lugs were oriented properly (side to side) and yes, the input is the power switch, pretty standard.  I can't wait to get home from work so I can fiddle around with the pedal.

[captntasty]

There are a number of ways to wire this up, or at least they look different.  On the 3PDT layout on the FAQ page the LED is coming from the middle column on the switch whereas in the Fulltone layout the LED is coming from the side column... no difference really, they both do the same thing.  The other thing to remember when looking at switch layouts is that they are generic... many pedals route effect signal from the board to a pot - volume or boost or in your case, wah....

If I'm understanding correctly, you have spliced some hookup wire into the + battery lead before the board...?  Typically I would run a seperate wire from where the + battery lead is soldered into the board - in this case that would be hard with the connectors they use.  You could tie into the 9v supply at the top of R7, soldered to the underside - it's a nice big pad!  That lead would be routed to lug #9 on the switch... no resistor.  Then you would run another hookup wire from #8 (cut to necessary size) to wherever your LED is located.  Solder the 1k resistor to the + LED lead and solder the wire from lug #8 to the resistor on the other side.

Those are the only funky things I hear in your description - 1. the lead to supply power to the LED is (if I'm understanding correctly) tapped right from the battery and not the board.  2. that you have the resistor on lug #9 as opposed to lug #8.  That setup is a bit out of the ordinary but in some sense should work... you might try these minor adjustments for due diligence.  Here is a specific link that gives a visual - remeber that it does not take into account the wah pot being wired in but will give a good generic overview.
http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_tb_battery.gif  this assumes that you haven't also added a DC jack - that's a whole other can of worms! 
The other place to check is the input jack...  I assume if you followed the instructions you've cut the brown lead and run that to the switch, etc...  something is shorting out at the input jack.  Where is the LED grounded to?  If I had to pick a ground spot I would say on the output jack sleeve (solder in with the black lead that is already there).  It can be grounded to different places but that is the easiest place in this pedal.
Good luck and keep updating...

[Voxin]

Again, thanks so much for replying to me.  Well, I went home for lunch and started tinkering around, and I reviewed all of your suggestions.  I soldered a new lead directly into the 9V supply and swapped the resistor from lugs 9 to 8.  As I didn't have enough time, I didn't permanently solder the ground in yet, but I currently have my ground lead taped on the input jack (the lug on the far right, I think it's the 'ring') because I read in another forum that the ground should be there in order for the LED to turn off when it's unplugged.  To my surprise when I plugged everything in, the LED lit up when I stepped on the pedal.  One problem left to solve...the LED still stays lit when the cables are unplugged from the Wah; other than that, everything seems to be working properly.  I think that when I get home I will play around with the ground positions and put it on the output jack rather than the input as you have stated.  Either way, will grounding it on the ring of the input jack damage anything?  One more step.....I hope!  Thanks.

[captntasty]

So you're getting somewhere now... you're welcome on the help - that's what this site is about.  Hopefully you learn a thing or two along the way....

grounding on the input shouldn't harm anything... after opening my 847 up (strangely enough my replacement inductor came today and I had to open it up anyway!) I realize how confusing the wiring in this thing is because of the harness.  I do think the input jack is a good place to ground the LED, another option if that doesn't work is anywhere along the rail on the board that runs from the purple lead to a capacitor - everything up to that cap is ground. 

The input grounds should be reserved for completing and breaking the power circuit - when you plug in to the stereo jack with a mono guitar cable/tip sleeve jack you join the ring and sleeve jack lugs across the plug - because it is not a stereo plug which has a tip a ring and a sleeve along the plugs length - thus completing a circuit for current to flow.

I think what might be happening in your case is that you have grounded to the input jack and it might be keeping the power circuit open or just plain mixing something up.  The layout of the input jack on the 847 is a bit of a big loop compared to most of the stuff that is built DIY.  If you ground to the ring lug (should be a white wire on that) you are hooking directly to the battery negative/ground, probably keeping the LED powered all the time - the LED was shorting out before when you plugged in and now it is connected directly to the battery, thus it's on whether you have a plug in or not.

I hope I've helped or at least stimulated your brain for further inquiry...  sorry my posts tend to ramble on - it's sort of stream of conciousness...  Peace

[Voxin]

Thanks again, don't worry about it, I love reading what everyone has to say.  Well, if it's not doing any damage to the wah, I think I'll leave it the way it is due to the fact that I use an adapter on the wah (well, a modded adapter with a 9V clip on it) and I'm not too concerned on it draining batteries etc.  So thanks again for the help.  Good luck with your 847!  I think I'm going to read up on some of the boosters out there..I'm going to challenge myself with that project in the next little while.  So I'm sure I'll be back!