Echo Base Issues

[flanagan0718]

Hey guys,
     I finally cleared my bench of most pending projects and finally and back around to this. I tried testing it and was only getting bypass, no delay. I checked for bridges and there are none. There is a bit of a whine too but that's probably just a ground thing. I know a bunch of you have built this and have had a lot of success with it too. I was wondering if anyone could lend a hand and help me debug it. Here are my voltages...

     TL072                                   TL072
1. 5                                           1. 5.32
2. 5                                           2. 4.9
3. 4.5                                        3. 4.9
4. .2                                          4. 209mv
5. 4.97                                       5. 5.2
6. 4.97                                       6. 4.9
7. 4.97                                       7. 4.9
8. 9                                           8. 8.78

     PT2399                                 CD4066BE           
1. 4.98                                       1. 4.63
2. 2.48                                       2. 4.64
3. .5                                          3. .46
4. .4                                          4. .45
5. 2.9                                         5. .3
6. 2.48                                       6. 4.3
7. 3.5                                         7. .3
8. 3.5                                         8. 2.48
9. 2.48                                       9. 2.48
10. 2.48                                     10. 4.6
11. 2.48                                     11. 4.6
12. 2.48                                     12. 8.63
13. 2.48                                     13. 8.8
14. 2.48                                     14. 9
15. 2.48
16. 2.48

      2N5089             BC560                  78L05
E. .3mv                E. .77v                   O. 4.98v
B. .3mv                B. 259mv                G. .3mv
C. 8.6v                 C. .4mv                   I. 9v

Hear are a couple of pictures too.





Thanks in advance, you guys are always so helpful.

[Morgan]

Voltages look okay to me (although I'm not super familiar with what the voltages should be on the 4066), so it's probably the wet signal being blocked by a bad solder joint. You can use the shotgun approach and just reflow all the joints on the pcb a couple of times to see if the wet signal comes to life. Or probe the signal path to see where you loose the wet signal (assuming you have a signal tester/audio probe).

The wet signal goes through 4066 pins 1 & 2, then into the PT at pins 15/16, then out of the PT at pins 13/14, then back through the 4066 at pins 10/11. From there it goes through the level pot and mixes with the dry signal.

Another thing to check is to turn all the knobs all the way up and see if oscillates or gets any other noise that might be coming from the PT chip. If it oscillates, then the delay circuit is working but signal is not getting to the input of the delay circuit for some reason. If you don't get any extra noise, then maybe the 4066 is not passing signal.

The PT voltages look good; I've never seen one that won't pass delayed signal when the voltages are okay (not that it can't happen though).

[flanagan0718]

The wet signal goes through 4066 pins 1 & 2, then into the PT at pins 15/16, then out of the PT at pins 13/14, then back through the 4066 at pins 10/11. From there it goes through the level pot and mixes with the dry signal.

Another thing to check is to turn all the knobs all the way up and see if oscillates or gets any other noise that might be coming from the PT chip. If it oscillates, then the delay circuit is working but signal is not getting to the input of the delay circuit for some reason. If you don't get any extra noise, then maybe the 4066 is not passing signal.

The PT voltages look good; I've never seen one that won't pass delayed signal when the voltages are okay (not that it can't happen though).

I'll check the wet signal path tonight. Thanks for the info. I did do a little probing last night but nothing really came up. I might try a new 4066 or PT2399 if nothing turns up. I tried all the knobs and I got no oscillation. I did notice a hiss but I think that might be a ground issue. So I think the "wet" is being blocked before the PT like you said.

[flanagan0718]

So, I got to sit down and debug this thing last night. I hooked it up to my rig and I guess just the threat of the probe  made it work. Sounds bad ass! I hooked up the LFO switch and the LED pulses with the speed of the modulation. It's quite awesome. I'll try and get this thing boxed this weekend. I think I might add the "dub madness" mod too. Thanks for the help Morgan.