Little Angel has no chorus

[pulsewidthmod]

I posted this is the official thread for the Little Angel, but figured it might be overlooked (i need help!!!!!!) I've built two of these (both different layouts) and both have done the same thing - nothing. They pass audio when turned on, but no chorus.

I'm using the layout on page 8 and audio passes through but no effect. I've looked through this thread and I'm stumped. Here's my readings:


PT2399:
5.04
.83
0
0
.42
1.94
0
.74
2.52
2.34
1.16
2.52
.34
2.5
2.52
.34

TL072:
1.41
.09
.09
0
.06
5.05
9.55

Here's a photo of my build, I've made sure that all my soldering is good.

[bluebunny]

There's a bunch of pins that look like they have voltages somewhat out of kilter.  Pin 2 of the PT (Vref) should be half the power supply, so around 2.5V (in this design, it does the "wobbling", but I didn't think it should wobble quite so far).  A lot of the 072 it at or near ground too, as are a couple of the RH pins on the PT.  Double-check your connections for shorts and/or opens.  Remember to measure from pins and leads, not from solder.  Is the PT getting warm when it's powered up?  Can you detect the wobble on pin 2?

[Mustachio]

Is that a L7805 instead of a 78L05 I believe their pin outs are opposite so if you spin it around it should work.

Like bunny said the voltages are off from what I seen posted to the net. Besides that, is that one resistor a 110R instead of a 100R, not sure that would make much of a difference there. The voltage regulator being oriented the wrong way would do it though. hopefully that's it . Good luck!

[anchovie]

Is that a L7805 instead of a 78L05 I believe their pin outs are opposite so if you spin it around it should work.

Really? The 2399 has 5V on pin 1, which suggests that at least that part is working!

[Mustachio]

Yeah they have diff pin outs






I agree with ya, pin 1 he says is getting 5v, so thats strange.

[pulsewidthmod]

I managed to find a 78L05. I'm putting it on the birthday layout that I made. (Yes this one was doing the same thing as the one I posted. Audio was going through but no chorus.)

When I swap it out, I"ll post an update. Should be within the next half hour or so.

Thanks dudes

~ pulsewidthmod (also answers to maeghan)

[pulsewidthmod]

I GOT IT WORKING 

It was the VR ... i found a 78L05 (the smaller package) and inserted it on the birthday layout ... now all i need to do is etch a new board and drill the enclosure ...

oh yeah, and figure out graphics ... wooo hooo!!!!

[Mustachio]

Awesome you got it working!

And oops I'm sorry really thats my bad for not paying attention to your name and tag at the bottom ( I should have said she instead of he) I'm not a sexist I swear!

You can still use the larger L7805 package the only difference is pinouts and max voltage. Just spin it around backwards.

[pulsewidthmod]

Awesome you got it working!

And oops I'm sorry really thats my bad for not paying attention to your name and tag at the bottom ( I should have said she instead of he) I'm not a sexist I swear!

You can still use the larger L7805 package the only difference is pinouts and max voltage. Just spin it around backwards.

please ... no worries, and thank you. Now I want to slow the LFO down ... hmmm, i'll figure it out ... or, if i don't ... i'll be sure to post here

[deadastronaut]

slowing the lfo..

try changing the 10uf to 22uf around the lfo.  usually works when ive been messing with lfo's.....make it switchable too. 

[pulsewidthmod]

I'm going fudging crazy ... my little angel works when i plug my iphone into it ... when i plug my guitar into it, it gets noisy and works in bypass and then no audio goes through when it's turned on.

But when i run my iphone thru it with the pedal turned on ... i get chorus ... what the hell ... i've tried pulling the plugs out a little seeing if was going to the other lug on the jack ... what da fudge ... i seriously could cry right now ... i know that sounds stupid ... but i've been working on this pedal all god damn week.

[pulsewidthmod]

whups i forgot to post this:

[Mustachio]

You know the way you describe it working one way and not the other makes me think its all wired correct. I use a bit different of a 3pdt wiring but yours seems fine.(especially since it works one way) 

So with all that said It sounds like your having the common pt2399 lock up issue. try tacking a 2k resistor from pin 6 to ground.

[pulsewidthmod]

Hmmm ... Here's the weird thing about this f-ing pedal ... once i turn the power on, i use an audio probe to check the circuit for audio ... i put it up on the tip of the input plug and i get no audio. I get no audio on the input lug ... what am i doing wrong? Is this not strange?

I'll try the pin 6 fix.

[pulsewidthmod]

Here's my reading on the ic's:
this is for the birthday edition of the little angel and i've made two mods ... r13 is a 2.2 now to give the chorus more depth and I'm using a TL072

It's really weird that that once i turn the pedal on, i can't even get audio at the tip of the input plug when i take my audio probe to it.

PT2399:
1.)   5
2.)   .85
3.)   0
4.)   0
5.)   .6
6.)   1.76
7.)   .01
8.)   .69
9.)    2.5
10.)  2.3
11.)  1.17
12.)  .33
13.)  2.47
14.)  2.47
15.)  2.48
16.)  .34

TL072:
1.)   3.19
2.)   .09
3.)   .22
4.)   0
5.)   .05
6.)   .05
7.)   0
8.)   9.56  (this is what my power supply puts out)

[Mustachio]

adding the 2k to pin 6 probably is a good idea in general just to protect from lockups if one may ever occur.

Ok So at first I was going to mention the input jack looked weird to me. but its sort of hard to explain.

So the lug that would connect to the tip connection of the input jack is usually directly across from that tip connection post. And the ring is usually the same direction across from the piece of metal that makes contact. and then the sleeve is at the base which looks correct as ground.

So thats how It normally is. You can look on the side and follow with your eye and see which are connected to which. In your picture It looks like the lug your using is going to the center of the pancake and usually thats the ring and the bottom one is the tip, and the sleeve is well there in the center at the sleeve. So maybe you have a jack thats constructed different ? Continuity test it with your multi meter so you can figure out which lug connects to the sleeve and which to the tip.

Sorry if thats hard to follow its sort of hard to explain and the picture might just be playing tricks on my eyes.

That also leads me to think the ipod your plugging in,,, are you using a stereo 1/4" adapter that would be feeding an audio signal on the tip and the ring. That would make sense if what I thought about the jack construction is correct.

Also this is how I usually wire my foot switches
http://generalguitargadgets.com/pdf/ggg_sw_3pdt_tb_gi_dcj.pdf

Also maybe try wiring it up direct no switch for a minute just to check if its the circuit or hardware

[pulsewidthmod]

I've done a continuity check ... i've got it soldered right ... should i try connecting the tip and the ring together? I know this sounds strange but i can't think of anything else.

Also, why would i not be able to get any audio at the tip of the plug when I turn the power on? (i'm using my audio probe.)

[pulsewidthmod]

I bypassed the switch and connected the circuit and nothing ... i tried the probe and when i'm getting no audio at the input when i should be getting audio. This is strange.

I had one of these working but i etched another board because traces had come up ... i just don't understand this.

[Mustachio]

Ok so you bypassed the switch and straight at the input you get nothing??? Break in the wire ? solid core wire ? Frustrating I know , stick with it you will get it.

Your doing the right thing using the audio probe, got new pics of the new solder side of the new pcb might have a solder bridge some where and maybe a new component side pic as well since this is a new pcb.

[pinkjimiphoton]

hi maeghan, welcome to the forum!!

the prob is this.... pt2399's plain suck. all there is to it. once they latch up, they are DONE. worthless. first time it happens. it will pass audio, and on occaision will even work, but in this application, they just plain suck.

if all your voltages are ok WITHOUT the chip in, if you have a fresh chip, you can try it.  you can also try shorting the power supply to ground to "clear" it, which sometimes works, sometimes doesn't.

i've made these on veros, i've made 'em on pcb's, and i've bought 20 chips at a time and never gotten it to work consistently on any of my builds. they are real buggers!!

i think when they "latch up" they smoke something, or short something internally. i have some you could almost use for a fuzz.

+1 on jim's last post... solid core wire can lead to all kinds of crazy stuff.

but i suspect most 2399's are crap.