Zombii LED and voltages. Bad power jack?

[cajone5]

*** I've done some more checking and think I've sorted it (see post 3) -- would love to get some feedback if anyone's had a similar issue before -- Thanks ***

I'm about to loose my freakin' mind.  I've got my zombii up and running and for the life of me I cannot get the LED to work.  I am using haberdasher's (sp?) board and, like always, he does fantastic work.  However, for some reason I couldn't get the LED to light when using the pads on the board.  No bother.  I can wire it off board... or so I thought...

I hooked it up per the usual (see the standard madbean diagram here... http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf

Nothing.

Flipped the polarity incase a momentary lapse of sanity occurred and I forgot how to read the polarity of an LED... still nothing.  So i start poking around and measuring voltages... hmm... voltage across the LED is only like 0.8v... weird... well certainly I must have done something dumb.  So I go and double check the power supply... yep -- about 9v tip to sleeve of the connector from my PP2+.  Oh, and the effect sounds killer and works marvelously in both bypass and with the effect on.  So i measure voltage across the two pads on the 9v tap... 0.8v!!! WTF!?

How the hell can the voltage be 9v on the power supply and 0.8 directly on the other side on the pads of the 9v tap?  I even pulled another tap out and made sure that the laws of physics still apply.  Yep, 9v across the pads of a fresh one that's not in the circuit.

So seriously, can someone try to make some sense of this???  I mean I'm pretty sure this thing is defying the laws of physics right now...

[cajone5]

BTW here are some shots of the pedal as it is now...





I haven't re-wired the LED because I want to figure out what the heck is up with the measured voltage before I try again.  The purple wire will go to the + lead of the LED and then I'll run a CLR to the top-middle lug of the switch.

Hopefully someone here can set me straight...  Bueller?

[cajone5]

So checked and rechecked and then realized (after comparing with my Zvex) that I'm almost certain that this is actually running at 0.8v.  It doesn't oscillate and some of the higher settings on the gate knob and lower settings on the fuzz knob don't pass much, if any, signal.  Has anyone ever had a power jack issue like this?  Apparently the circuit was tweakable enough to get some sounds out of it even with such a low voltage running to it.  Anyway, I'm going to pull the power jack, disconnect the wires and see if I can read 9v across the terminals with power plugged in to see if the jack is bad.  If it is, it gets replaced.  If it doesn't, well, then I try again with it, I guess.  Can the circuit cause less power to be seen across the terminals somehow?  I wouldn't think so, but it seems the folks here are much more knowledgeable than me so I'll wait to see if anyone weighs in...

[hammerheadmusicman]

this may sound stupid, but all manner of weird and wonderful things can happen when doing this stuff!!

1) Have you tried switching the LED for a known working one?

2) Have you checked the resistor that is responsible for the LED is the correct one?

Good Luck


George

[cajone5]

Yes, and yes.  Right now I don't even have the LED hooked up.  Just measuring voltage at the jack... So I'm going to unsolder the jack and see if I can plug it in and read across the terminals and measure 9v.  If not, I must have a bad jack.  If I do read 9v I'm not sure what I'll do... we'll see in a few minutes...

[cajone5]

OK I'm officially baffled. 

Remove all wires and checked the jack -- 9V.  Worked.  Jack is OK
Connected the LED -- 9V.  Worked.  No issue wiring the LED.
Finally, connect the last wire -- power from the board to the jack... 0.8V! Ahhh!  Does this mean there's a short on my board somewhere that's bleeding the power away?

[cajone5]

I build it from the etched board at the bottom of this and may have found an error in that etch...

http://www.madbeanpedals.com/projects/Zombii/docs/Zombii_ver.5.pdf

Take a look at where the 9v connection comes into the circuit.  It looks like it runs up to lug 2 of the stability pot for the board on the first page and in the schematic but runs to lug 1 in the etched board at the bottom.  Going to try cutting the first trace and adding a mini jumper to lug two and see if that sorts it 

[cajone5]

Nope. 

Is it possible the power is bleeding to ground somehow?

[trickpony]

You sure you got that standard wiring diagram right? It doesnt look right from the picture to me.

Ben

[trickpony]

In particular I dont see the grounding wire that connects the 3 pads on the switch...are you sure you are getting continuity to ground when the effect is engaged?

Ben

[jkokura]

In particular I dont see the grounding wire that connects the 3 pads on the switch...are you sure you are getting continuity to ground when the effect is engaged?

Ben

That's because he's using a different bypass method. They bypass switch looks fine.

Jacob

[cajone5]

A grounding issue somewhere would make sense... hm... Any reason I would get a redicution in voltage of a little over a factor of 10?

As far as the switch goes, I used a different switch wiring scheme actually... this guy...



It looks odd from the photo but here's how my switch is hooked up (lugs numbered from top left to bottom right, across then down)...

1 - Circuit Board "in"
2 - CLR from LED negative lead (not shown hooked up in the photo though, but it is now)
3 - Circuit Board "out"

4 - Input Jack Tip
5 - Ground (Input Jack Sleeve)
6 - Output Jack Tip

7 - Jumpered to 9 w/ null resistor
8 - Circuit Board "in"
9 - Jumpered to 7 w/ null resistor

So it's slightly rearranged but ultimately I think it's the same (functionally) as the madbean std. wiring diagram.

[cajone5]

I'll triple check the solder side of the board for anywhere I could have overdone it and created a solder bridge... Man, I thought this would be a simple debug.  Who knew it'd last thing long...

All I know is that the voltage is fine UNTIL I connect the 9v power to the board.  Then the measured voltage drops to 0.8v from about 9.3v.  Man I wish I understood all this better.

[trickpony]

2) CLR from LED negative lead (not shown hooked up in the photo though, but it is now)

To Verify, you have the CLR (current limiting resistor of say 4.7K) connecting the positive (long) lead of the LED to 9V (your purple wire)  and have the negative lead (short) connected directly to pin 2.
Right?

Also You have the RED wire going to 9v on the board right? I can't tell by the picture but it needs to be connected to the same place as the purple wire. If not, then you are dis-engaging it when you plug in the 9v adapter.

Ben

[jeffaroo]

Red, Yellow, Green and Orange Led's works on 1.8 to 2 volts, White, Blue and Purple need 3 to 3.5 volts for proper operation. All 3mm & 5mm LED's operate on 20ma or 10 ma when noted.  A current limiting resistor should be used when lighting LED's in most applications. To find the correct resistor subtract led working voltage from your source voltage then divide by .02  for 20ma and .01 for 10ma, use a resistor equal to that amount or greater, do not use a smaller resistor.