TonePad Tremulus Lune debug (kind of long... lots of info)

[Fuzzy-Train]

http://www.tonepad.com/getFile.asp?id=84

Bypass works, but when I engage the pedal I get no sound at all. Here's some voltages and various info... the 4558 seems wrong to me  PS is at 9.46v (1spot PS)

All knobs were set at zero, and the trimmer was set in the middle.

IC1           
1 4.72v       
2 4.72v       
3 4.48v       
4 0 v         
5 4.48v       
6 4.47v  this pin makes a popping noise when the probe touches, and makes slight am radio frequency noises     
7 4.71v       
8 9.47v     

Most of the pins from IC2 4558 are jumping from 2v to 7v from except for pin 7 which goes from around 1.5v to 8.5v. Pin 4 is at 0v and pin 8 is at 9.47 though.

Some more various info that I noted..  The rate LED is hooked up to a 3PDT, it flashes with the time and reacts the way (I assume) it should when I fiddle with the knobs. The positive lead of the LDR varies between 3.2v and 3.8v, the neg on the LDR varies between 6.5v and 7.5v. I think the LDR is not oriented properly... I have the positive on the bottom and the neg on top.The lead going to pin 6 (IC1) from the LDR is at 4.75v, the other lead going to pin 1 (IC1) is at 4.72v.

I wired the 3PDT like this, and I used the other pins to engage the rate LED.
http://www.generalguitargadgets.com/diagrams/switch_lo_dpdt_std.gif

Also the enclosure is not grounded because I used some plastic jacks from my old wah PCB.

I didn't do any mods, except I subbed the TL072 for a quieter NE5532P, and I used a 50k trimmer... the project file said 25k but I might need a 100k depending on the LDR used so I went in the middle. The LDR used was a SB VTL5C2.

I haven't had the time to poke around with my audio probe yet, but I have a question regarding that. Peter Moore says to follow the signal thusly: "input>1uf>47k>OA>Cell>OA>1uf>Output" could anyone elaborate on this a bit for me? This info was given for the fuzzcentral layout though.

Thanks in advance for the help, and happy building everyone!

[rubix cube]

if you look at the tonepad schematic, just probe at every juction of components in the signal path.  This is the path mentioned in your post.  If you get nothing at the input, your wiring is wrong, if you get nothing after the 1uF cap, that might be dodgy, if you don't have signal at pins 1&2 of IC1, that might be dodgy, and so on.  IC voltages all look alright to me.

[Fuzzy-Train]

I'm getting signal all the way to pin 1 of IC1, but I got nothing at pin 2. I tried re-soldering all the pins of IC1, and I'm still getting no signal. I tried replacing the NE5532P with another one I had, still nothing. I tried replacing both IC's... nothing! 

Everything is oriented properly. I went over it atleast a dozen times... wiring, part values, IC orientation, LDR orientation.  So demoralizing. Especially since I can see the LED rate flashing in an almost teasing fashion.

Am I missing something?

This always seems to happens to me with somewhat easy builds, and it always turns out to be something silly. I'm too tired to figure it out today though.

Thanks for the help.

[Fuzzy-Train]

Bump.

There's some mods to the schematic:

In the Audio path:
Change the two 47k (these are the 2 that go to pin1 and 2 of IC1) resistors to 220k.
Change trimpot to a 10k, you may want to use a panel mounted pot for easier adjustment instead.
Add a 330pF capacitor across opamp pins 6 and 7.

In the LFO:
Change 100ohm resistor to 2k7.
Change the 100uF cap to a 10uF.

These weren't changed on the layout so I didn't do these to mine... could that be the problem perhaps? I'm getting continuity to from the two 47K's to pin 1 and 2 of IC1, so it''s really weird that I don't get a signal on pin2.

Any and all suggestion/ideas are truly appreciated.

[John Lyons]

Alex
Audio Probe these places (looking at the schematic) to see..er... hear if you have a signal.
Pin 2 of IC1.
Pin 1 IC1
Pin 6 IC1
Pin 7 IC1

I'm not familiar with the circuit but it looks like if the LDR/oscillator isn't working then you will get no signal.
If the signal stops after IC1 pin 1 then the LDR isn't operating corectly and letting signal through.

You can pull out the LDR and put in a temporary LED to see if the oscillator is working correctly. It should flash in time and depth to the controls. In fact, check your Vactrol to make sure it's installed correctly. The stripe on the layout matches the flat side of an LED. You can probably just touch an LED to the legs of the Vactrol (while still installed and see if you get any flashing. If yes then the Vactrol LED is working and installed correctly.

[Fuzzy-Train]

My man, my man!!! You are a god my good sir.

I had a feeling it might of been that, but the many times I went over it I always thought it was orientated properly. Easy fix, but I don't have time to do it right now.

Once again John, you have saved my build.

Thanks for all the help. Here's some pics:





I'll post proper pics in the pic thread with guts. The two knobs and LED up top are the speed controls and rate LED.

[John Lyons]

Well.., with any luck that's the problem!
Seems to make sense to me though.

John