Building the Echo Base PCB

[suryabeep]

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!

[Taylor]

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]

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.

[Taylor]

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]

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

[Taylor]

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]

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.

[ReverendRaviRobot]

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]

Hi everyone, I just added the mods recommended for the feedback stuff and now I don't 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

[Taylor]

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]

Hi everyone, I just added the mods recommended for the feedback stuff and now I don't 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.

[ReverendRaviRobot]

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]

I finally finished my Echo Base yesterday.  I originally didn't 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.  It's still a tight squeeze up near the in-jack, but it works.  And, BTW, it sounds great.

[Taylor]

For those who've been waiting, I finally have the Echo Base PCB back in stock!

http://www.musicpcb.com/pcbs/echo-base-delay

[geklimper]

Hi,
finished the echobase some days ago, but have some problems with it.

Running on 9 V, Mods: LFO off, Clean Signal Kill, LFO Waveshape, Dub Madness, Humbucker friendly

Clean signal ok, Kill switch is working.
LFO Waveshape: changes between triangle and square wave
Dub Madness: working

LED: no function

Echo is not working for the clean signal. With Tails on and Dub Madness on or Feedback knob full on, a lot of noise builds up. This is independent from the clean signal and I can influence it with the Time and Mod Depth knob.

So in a way it's working, but the connection between dry and wet is missing. I tried to read the schematics (that I don't really understand) and controlled the board multiple times, but didn't find anything.

The voltages:

PT2399
1: 5
2: 2,5
3: 0
4: 0
5: 2,7
6: 2,5
7: 0,73
8: 0,7
9-16: all 2,5

4066
1: 4,35
2: 4,35
3: 0
4: 0,04-0,08
5: 0
6: 0,5
7: 0
8: 3,6-5 (triangle wave)
9: 0,02
10: 4,65
11: 4,65
12: 9,44
13: 1,37
14: 9,68

5089
E: 0
B: 0,62
C: 0,99

TL072 (left)
1: 5
2: 5
3: 4,55
4: 0
5: 5
6: 5
7: 5
8: 9,72

TL072 (LFO)
1: 5
2: 5
3: 5
4: 0,84-0,97
5: 3-6
6: 5
7: 2-9 (almost square wave)
8: 8,85

I have audio on pin 1 and 7 from the 7072 (left) and pin 10 at ic 4066. At IC 2399, I have very low audio on pin 16 and 13, low audio on pin 14 and more output at pin 15.

Any hint where to look at would be very welcome.

[brittney]

I finished my musicpcb echo base this evening.

Appears to be somewhat working....

the tails switch seems to do nothing at all
The echo only does one single repeat under all settings

Any suggestions as to where to start looking?
I'm guessing its an issue in the CD4066 not actually switching when the tails is switched

Anyone know what kind of voltage/signal should be at the tails switch?

thanks

[Taylor]

Hi,
finished the echobase some days ago, but have some problems with it.

Running on 9 V, Mods: LFO off, Clean Signal Kill, LFO Waveshape, Dub Madness, Humbucker friendly

Clean signal ok, Kill switch is working.
LFO Waveshape: changes between triangle and square wave
Dub Madness: working

LED: no function

Echo is not working for the clean signal. With Tails on and Dub Madness on or Feedback knob full on, a lot of noise builds up. This is independent from the clean signal and I can influence it with the Time and Mod Depth knob.

Sorry, I had trouble understanding this. It sounds like your delay chip is doing what it's supposed to do, but the audio signal is not getting into the delay chip, is that right? So you get delayed noise, but no delayed version of your input signal? If so, it sounds like most of your sections are working, but perhaps the issue is around the 4066 switch.

For the LED, you may need to alter the value of the 50k resistor to the bottom right of the 4066. For many LEDs this will be too high - try a lower value around 5k.

[Taylor]

I finished my musicpcb echo base this evening.

Appears to be somewhat working....

the tails switch seems to do nothing at all
The echo only does one single repeat under all settings

Any suggestions as to where to start looking?
I'm guessing its an issue in the CD4066 not actually switching when the tails is switched

Anyone know what kind of voltage/signal should be at the tails switch?

thanks

If you only get one repeat, it probably means your feedback path is messed up somewhere. Signal is getting into the delay chip, but not back from the output of that to its own input. The parts to the right of the 2399 and the feedback pot would be the place to check. See if the signal is coming out of the center lug of the feedback pot.

[geklimper]

Hi,
finished the echobase some days ago, but have some problems with it.

Running on 9 V, Mods: LFO off, Clean Signal Kill, LFO Waveshape, Dub Madness, Humbucker friendly

Clean signal ok, Kill switch is working.
LFO Waveshape: changes between triangle and square wave
Dub Madness: working

LED: no function

Echo is not working for the clean signal. With Tails on and Dub Madness on or Feedback knob full on, a lot of noise builds up. This is independent from the clean signal and I can influence it with the Time and Mod Depth knob.

Sorry, I had trouble understanding this. It sounds like your delay chip is doing what it's supposed to do, but the audio signal is not getting into the delay chip, is that right? So you get delayed noise, but no delayed version of your input signal? If so, it sounds like most of your sections are working, but perhaps the issue is around the 4066 switch.

For the LED, you may need to alter the value of the 50k resistor to the bottom right of the 4066. For many LEDs this will be too high - try a lower value around 5k.

Hi Taylor, thanks for your support! I changed the resistor, but still no LED. I had a signal at 4066 pin 8, but nothing at pin 9. On control pin 6 I had only 0.45 V, what means "off" (found this in another thread, https://www.diystompboxes.com/smfforum/index.php?topic=60662.60). The only thing to make this off is the bypass switch, and because I want to use the echobase in my eurorack, I had no bypass switch and had these contacts open, assuming bypass means closing. Bridged it and voila, everything is working. Stupid mistake, but learned something on the way.

[Ben N]

Help! Taylor, or anyone who can help.

After having this board sitting around for God knows how long, I'm finally populating it. But I managed to strip the pads for one of the resistors--don't ask, I didn't even know this level of cluster@#$% was possible with a plated through board--and I am having trouble figuring out where to tack the resistor onto other components.

The resistor in question is the 47k on the right side of the PT2399, between the 1n cap and the 10k resistor. Referring to the schematic, I'm not sure if it is the 47k that connects to pin 14 or pin 15 of the PT2399, and, that said, I'm also not sure how the various components line up in the layout--that is, even if I was sure which components it's supposed to connect to, I don't know which side is which.

TIA