Author Topic: Building the Echo Base PCB  (Read 179249 times)

0 Members and 1 Guest are viewing this topic.

suryabeep

Re: Building the Echo Base PCB
« Reply #720 on: August 25, 2017, 10:39:05 PM »
Hi Everyone,
So i finally got around to finishing up the echo base and of course, I messed up somewhere. I'm getting a loud buzz in both bypass and delay mode, and no guitar signal at all. The Led lights up when I switch the effect on, and pulses with the LFO speed pot. Here are my voltages:
Left TL072
1- 4.96
2- 4.96
3- 4.51
4- 0
5- 4.96
6- 4.96
7- 4.96
8- 9.36

Right TL072
1- fluctuating between 5.76 and 3.94
2-4.95
3- 4.95
4- 0.85
5- fluctuating between 5.76 and 3.94
6- 4.95
7- fluctuating between 2.28 and 7.72
8- 8.49

4066
1- 4.60
2- 4.60
3- 0.89
4- 0.89
5- 0
6- 0.72
7- 0
8- fluctuating between 5.76 and 3.94
9- 0.44
10- 4.29
11- 4.29
12- 1.26
13- 9.16
14- 9.36

2399
4066
1- 4.95
2- 2.47
3- 0
4- 0
5- 3.19
6- 2.44
7- 3.19
8- 3.19
9-16 are all 2.47

What could be going wrong? Did I do something stupid? Thanks in advance!
Still in the process of learning, so bear with me if I ask dumb questions :P

Taylor

  • Poster2
  • **
  • Posts: 4076
  • Total likes: 30
  • The clean energy source of the future.
Re: Building the Echo Base PCB
« Reply #721 on: August 26, 2017, 03:03:36 PM »
Voltages look OK. Next I'd check the circuit with an audio probe. The left TL072 is the input and output buffers - try listening at pins 1 and 7 to see if you have any signal at those points (while strumming guitar or sending some music into the input). Also check pin 10 of the 4066 for audio, let us know what you hear at those points.

suryabeep

Re: Building the Echo Base PCB
« Reply #722 on: August 27, 2017, 06:19:23 PM »
Weird. I didn't touch the thing overnight and now bypass works. Now a new problem has risen though, there's no delay and activating the clean-kill switch completely kills all sound. The Level pot also gets loud in the middle of its rotation and gets softer at the ends. None of the other pots have any effect. None of the switches have any effect either, except the clean-kill. The dub madness momentary switch doesn't do anything either.

With the effect engaged, I get clean signal on pins 1 and 7 of the left TL072, and on pins 1 and 2 of the 4066. Nothing at pin 10 of the 4066. Clean signal at the output jack.The LED still pulses with the LFO speed pot.
« Last Edit: August 27, 2017, 06:39:56 PM by suryabeep »
Still in the process of learning, so bear with me if I ask dumb questions :P

Taylor

  • Poster2
  • **
  • Posts: 4076
  • Total likes: 30
  • The clean energy source of the future.
Re: Building the Echo Base PCB
« Reply #723 on: August 28, 2017, 03:35:19 PM »
Well it sounds like all of your sections are working, except for the 2399. The voltages on the chip seem right, so try probing pin 16 of the 2399, which is the input, and pin 14, the output. If you've got clean signal going in but nothing coming out, there's something wrong with the chip or the immediate surrounding parts.

suryabeep

Re: Building the Echo Base PCB
« Reply #724 on: August 30, 2017, 11:02:18 PM »
OK there is some wizardry going on in my garage. I haven't touched it in 4 days and now the delay works and the switches work? WTF?
Now there's a new problem, the feedback oscillates way too quickly in the rotation, I can barely up it to 20% turn and it goes crazy.
The rest of the pedal sounds great! LFO section is weird af, but I like it ;D
Still in the process of learning, so bear with me if I ask dumb questions :P

Taylor

  • Poster2
  • **
  • Posts: 4076
  • Total likes: 30
  • The clean energy source of the future.
Re: Building the Echo Base PCB
« Reply #725 on: August 31, 2017, 02:31:21 PM »
Hmm, strange. For the oscillation, there's a 20k resistor right under the feedback pot. You can increase the value to lower the overall feedback amount, so it doesn't oscillate as early.

pgorey

Re: Building the Echo Base PCB
« Reply #726 on: November 15, 2017, 08:43:35 AM »
I ended up trying a lot of different resistor values for that oscillation issue.  33k or 47k are great values for me :)  You get a little more resolution in the range of feedback.

Re: Building the Echo Base PCB
« Reply #727 on: November 24, 2017, 09:52:12 PM »
Just wrapped up a build of the EB. Everything worked right away, nice quality on the PCB! I managed to sub 2n3904 and 2n3906's for my particular unit.
I just keep running into one strange issue. When I power the unit up, sometimes I only get clean signal in both bypassed and engaged (LED functions). Like the delay portion isn't operating. Usually cycling power gets it running. It doesn't happen every time, and physical stresses don't seem to make it come or go.
I haven't tried a different 4066, 2399, or the proper transistors. I'm using a fixed regulator on my input voltage to hold it at 10 volts with ample voltage going into that to keep it steady. Do you have any suggestions or has anyone else had bypass issues on power-up where there was no delay? Thanks in advance!

suryabeep

Re: Building the Echo Base PCB
« Reply #728 on: November 25, 2017, 11:52:12 AM »
Hi everyone, I just added the mods recommended for the feedback stuff and now I donít get any audio at all, even probing on the input jack. I replaced the 20K beneath the feedback pot with a 100K and the 27K for the dub madness with a 56K
Still in the process of learning, so bear with me if I ask dumb questions :P

Taylor

  • Poster2
  • **
  • Posts: 4076
  • Total likes: 30
  • The clean energy source of the future.
Re: Building the Echo Base PCB
« Reply #729 on: November 27, 2017, 01:26:48 PM »
Just wrapped up a build of the EB. Everything worked right away, nice quality on the PCB! I managed to sub 2n3904 and 2n3906's for my particular unit.
I just keep running into one strange issue. When I power the unit up, sometimes I only get clean signal in both bypassed and engaged (LED functions). Like the delay portion isn't operating. Usually cycling power gets it running. It doesn't happen every time, and physical stresses don't seem to make it come or go.
I haven't tried a different 4066, 2399, or the proper transistors. I'm using a fixed regulator on my input voltage to hold it at 10 volts with ample voltage going into that to keep it steady. Do you have any suggestions or has anyone else had bypass issues on power-up where there was no delay? Thanks in advance!

When the delay signal is not coming through, if you turn the delay time knob all the way up and down do you hear weird crinkly noises/pitch shifting? If you do, it would indicate that the delay chip and everything from its output to the output amp is working, but the problem is somewhere between the input amp and the delay chip's input. If you don't hear any of that, it might point to a problem with the 2399 itself. I remember that with some other 2399 projects people found certain situations where it wouldn't power up right - maybe something to do with the double-regulating (you've essentially got the 5v regulator in series with the 10v regulator).

Taylor

  • Poster2
  • **
  • Posts: 4076
  • Total likes: 30
  • The clean energy source of the future.
Re: Building the Echo Base PCB
« Reply #730 on: November 27, 2017, 01:32:11 PM »
Hi everyone, I just added the mods recommended for the feedback stuff and now I donít get any audio at all, even probing on the input jack. I replaced the 20K beneath the feedback pot with a 100K and the 27K for the dub madness with a 56K

Even if adding those mods messed up the delay signal path, it shouldn't have any effect on the signal at the input jack since there's buffering in between those points, so you may just have broken the input wire in taking it out of the enclosure and putting it back in, or shorted the input to ground against the enclosure. Try checking for continuity to ground at the input.

Re: Building the Echo Base PCB
« Reply #731 on: December 03, 2017, 02:27:01 PM »
There was no delay-regen noise when messing with any controls when it was in the failure mode. I managed to get it to reliably fail on power-up by having both delay time and depth pots at full minimum. Since the board was built, mounted, and fully wired into my chassis, I opted to place a 150 ohm resistor in series with the 57K delay time pot at my front panel. It now powers up and operates reliably every time.
The dual regulator system was so I could run the echobase off a >12+ volt supply since the 5V regulator seems to not only supply the PT2399 but forms a virtual ground for the op amps. Maybe I'm wrong, but either way it is up and running reliably now. Thanks for your assistance!

bcalla

Re: Building the Echo Base PCB
« Reply #732 on: January 01, 2018, 05:34:49 PM »
I finally finished my Echo Base yesterday.  I originally didnít properly account for the space required for top-mounted jacks.  Then I messed up the board / broke some traces trying to remove components, so I had to order a new board and start over. 

In any case, here is my take on the Echo Base.  I included pretty much every documented mod.   On my second attempt I needed to get the board to sit lower so I skipped the board mounted pots.  I also mounted a couple components on the bottom to allow the 7805 to lie flat.  Itís still a tight squeeze up near the in-jack, but it works.  And, BTW, it sounds great.







"Under certain circumstances, profanity provides a relief denied even to prayer."
       -- Mark Twain