Building the Echo Base PCB

[El Heisenberg]

Done. I had to go down to 5k! But it worked.

Man this PCB cab really take a beating. Ive taken the whole thing apart and done mods to it loke 8 times using really old solder iron tips.

[1878]

The problem with the bypass has gone (solder bridge on the tails switch) and I've had a go with the audio probe... Nothing conclusive. I'm wondering if it's the PT2399. I bought 10 of them from Ebay a while back and they were CHEAP !! Maybe they were cheap for a reason.

What makes it so frustrating is I can hear everything is working as it should !?!? All the controls work correctly, just this horrible distorted noise coming out of it.

I shall endeavour to persevere.

[Ginsengbob]

Sometimes while I have the pedal open a high hissing sound appears out of nowhere.
If I unplug the pedal and plug it back in the hiss disappears.
Anybody else have this happen?

[StereoKills]

Sometimes while I have the pedal open a high hissing sound appears out of nowhere.
If I unplug the pedal and plug it back in the hiss disappears.
Anybody else have this happen?

I had something similar that only happened for a few days, then disappeared. I had some modulating hiss that would go away when the mod switch was turned off and come back when mod was turned back on. It took about 1-2 minutes to happen after the pedal powered up. I meant to do some investigating, but the hiss hasn't been back in months.

[1878]

Just read this...

http://www.diystompboxes.com/smfforum/index.php?topic=86788.0

I had another go at debugging my build yesterday to no avail & I'm wondering if my previous thoughts were correct. I'm about to order a couple of chips from a more reputable supplier !!

[husc]

I have finished building the echobase, and after 3 hours of carefull and planned debugging.. I haven't got it working.

I read all the posts and tried all my knowledge, but now I could use some help.

problem:

No signal. Neither in bypass, nor delay!

(when I connect the input jack to an amp and amplify it very much, I do hear the dub madness mod I did and the oscillation effect when I open the feedback pot.!?)

What I got, so far:

- LED works, also goes on and off with the bypass switch.

- LFO switch works, as I flip it, the LED reacts to the 'lfo speed' pot

- checked and resoldered 2 cold joints and my wiring, everything looks good and seems to be connected

- I've measured the pinouts of all the ic's and compared it to the results posted on page 2 of this thread and don't notice anything weird.

- Audio probe, I probed and the input seems to get to the board just fine. I hear at the pins:
 
TL072 (on the input side of the board):
1 clean signal
2 clean
3 clean
7 delay signal

4066:
1 clean
2 clean
10 delay (muffled/slightly distorted)
10 delay (muffled/slightly distorted)

PT2399:
9 delay
12 delay
14 distorted delaysignal
15 delay (= this is what I would love to hear coming out of my amp!! )

I can measure more, post more results, but I am a bit at a loss here of where to look. Please, thanks for any help you guys can offer me..



       

[slacker]

TL072 (on the input side of the board):
7 delay signal

When it's in bypass do you get clean signal on pin 7, if you do then there can't be much wrong because that's where the output is taken from. I'd start be double checking your wiring to the jacks, make sure both the sleeves are grounded and that the connections to the tips are correct.

[Taylor]

So, we know your delay chip is working properly, which means voltages and the regulator are all good.

We know the LFO is working and the 4066 is at least mostly working.

So what's left would be the left TL072 and the audio path coming from the delay chip pin 14.

Probe 4066 pin 10 and let us know what you have.

[husc]

When it's in bypass do you get clean signal on pin 7, if you do then there can't be much wrong because that's where the output is taken from. I'd start be double checking your wiring to the jacks, make sure both the sleeves are grounded and that the connections to the tips are correct.

I get a clean signal if it's bypassed and I tried audioprobing the 'out' connection, nothing there.. when I insert the input cable into the output jack I get no signal at the 'out' connection!? Does that help?

Probe 4066 pin 10 and let us know what you have.

..at pin 10 of the 4066 I get a delaysignal, but loud and clipped!

[Govmnt_Lacky]

.. when I insert the input cable into the output jack I get no signal at the 'out' connection!? Does that help?

HUH??

[husc]

.. when I insert the input cable into the output jack I get no signal at the 'out' connection!? Does that help?

HUH??

When I feed a signal into the output jack (insted of the input) no signal comes through to the pcb at the 'out' connection. Is that more clear.. sorry.

[Govmnt_Lacky]

When I feed a signal into the output jack (insted of the input) no signal comes through to the pcb at the 'out' connection. Is that more clear.. sorry.

I think so....

Where exactly are you taking your readings (or audio-probing) at the PCB for the 'out' connection?

[husc]

When I feed a signal into the output jack (insted of the input) no signal comes through to the pcb at the 'out' connection. Is that more clear.. sorry.

I think so....

Where exactly are you taking your readings (or audio-probing) at the PCB for the 'out' connection?

At the bottomside of the hole marked 'out' . No audio there either way..

[Govmnt_Lacky]

When I feed a signal into the output jack (insted of the input) no signal comes through to the pcb at the 'out' connection. Is that more clear.. sorry.

I think so....

Where exactly are you taking your readings (or audio-probing) at the PCB for the 'out' connection?

At the bottomside of the hole marked 'out' . No audio there either way..

Not sure if you will hear a non-amplified signal with an audio probe (which I assume you are using)

Sounds like you may be grounding out your output signal somehow.

You should pull out the TL072 that slacker referred to previously and read between Pin 7 and ground. If you read a short then you just need to follow the path and look for potential problems.

Good Luck 

[slacker]

There's a 220n capacitor above the opamp below the "Level" pot what do you get if you audio probe both of its legs.
The side nearest the edge of the board is connected to pin 7 so you should get audio there the other side is connected to "Out".

If you've got a continuity tester on your meter try testing for continuity between out and ground, there shouldn't be any, but it sounds like something might be shorted to ground.

EDIT: posted the same time as GL

[husc]

..but it sounds like something might be shorted to ground.

PROBLEM SOLVED!

I had the wires soldered wrong at the output jack...  so focused, I didn't see the solution yesterday.
A goodnight sleep, your help and reading over the debugging FAQ again. Switched the wires around and boom, great pedal..


THANK YOU!! (I'll post pictures asap in the appropriate thread)

[slacker]

Cool glad you got it working.

[1878]

Hello Everyone.

I've swapped out the PT2399 and although better, it's still not working properly. I've checked all the values and they're correct, I've also gone over all the solder joints and they're fine too.

The effect is acting as it should. I can hear the repeats etc, but they're really distorted and muffled. The initial signal when the effect is engaged is fine, it's the repeats which are the problem. Any ideas ??

[Taylor]

Since sound qualifiers are relative, when you say it's distorted and muffled, you know that the repeats in a working Echo Base are not super-clean like a Boss DD-7 type delay, right? A certain amount of distortion and filtering ("muffled" sound) is normal. So are you get much more distortion and filtering than is normal with a PT2399 delay?

Probe 4066 pin 10 and let us know what you have.

[iccaros]

@ all (amptramp, FC, Zambo and all the rest of the smart people on the board.. So everyone)

What if the first stage was made also cathode follower?

I not a cathode follower for high impedance input and low impedance output?
I get that from my Directory of Electronic Circuits by Mathew Mandl printed in 1966.. It would require adding a capacitor from plate to ground like a .047uf... This will minimize signal voltage  variations that can cause degrading of the signal.