Building the Echo Base PCB

[Misterwinefine]

Hello I am in need of some guidance,  I have built the  Echo Base PCB from Taylor I received this board last week from his new batch of boards,  top notch I might add,  and I am having a few issues that I am sure I am overlooking.

The level out is fine as a dry guitar signal, but the delay is very faint.  If i turn the level pot I can here the change in the amount of delay but it is very very quite.  The dry guitar signal is good and loud still.  The LED on the is working and the tails switch and bypass switch are working as well. 

I have a dry signal through the Audio TL072 on pin 7 and 3   With an audio probe, I have audio on the PT2399 pins 15 loud, 14 very faint I can hear repeats faint as well.  I have audio on pin 9 and 12 as well.  I can hear the modulation as well.

One question is the wiring of the pots,  looking at the board as if it was sitting in front of youi,  Left to Right 1,2,3 is the way I wired the pots   I did not use board mounted pots.  And i think I have those correct!  Please correct me if I am wrong

I have looked over the values of the components resistors and caps and all look in order and correct.  I have reflowed all the solder joints, and I have replaced all the IC's with other chips to insure I didn't have a bad one.

I have checked all the voltages on all the IC's and transistors and they all read within the spec on the 78 page post on the echo base build on this site.  BC560 was subsitued with a 2n5087,  and I did check the pin out and insured it matched the required EBC placement,  it is the reverse of the BCS560.

I have read through this document and the other 78 page post and tried to figure out if I was missing something.  i am using a regulated power supply.  I do have 5 v on pin one of the 2399.

Any suggestions on what I should look at again, and what your best guess might be I am overlooking?  I greatly appreciate your help.

[btreim]

Hey Taylor and Slacker,

Having some issues with my build. It seems I'm having similar issues to 9aul back on page 27 of this thread but can't quite work it out.


Mods: dub madness on momentary foot switch

What it does: Longer single repeats. LFO knobs affect the delay time slightly

What it doesn't do: LED does not pulse with LFO speed. LFO is seemingly non-opperational, no more than a single repeat.

Here are my voltages: Something seems wrong here, but I can't find what the correct voltages are supposed too be in order to track it down.

TL072 -

1 - 4.97
2 - 4.97
3 - 4.55
4 - 0.00
5 - 9.38
6 - 4.97
7 - 4.97
8 - 4.96

4066

1 - 4.66
2 - 4.66
3 - 1.83
4 - 1.81
5 - 0.00
6 - 4.74
7 - 0.00
8 - 9.38
9 - 8.99
10 - 9.17
11 - 4.66
12 - 4.66
13 - 2.42
14 - 2.42

PT2399

1 - 4.97
2 - 2.48
3 - 0.00
4 - 0.00
5 - 3.10
6 - 2.48
7 - 0.86
8 - 0.90
9 - 2.48
10 - 2.47
11 - 2.48
12 - 2.49
13 - 2.49
14 - 2.48
15 -  2.48
16 -  2.48

TL072 -

1 - 3.03
2 - 3.13
3 - 4.97
4 - 3.00
5 - 3.63
6 - 3.13
7 - 4.97
8 - 3.01

2n5089

1 - 0.00
2 - 0.00
3 - 8.98

BC560B

1 - 1.05
2 - 0.56
3 - 0.00

7805

1 - 4.97
2 - 0.00
3 - 9.38

[Taylor]

I think you've numbered your pins the wrong way - they should go in order counter-clockwise around the chip like this:

http://upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Pin_numbering_01_Pengo.svg/460px-Pin_numbering_01_Pengo.svg.png

Correcting for that, it looks like the TL072 on the right side of the board, which creates the LFO, is not getting powered properly. Any chance you used the wrong value for the 220R (this means 220 OHMs) resistors (220k by accident)?

[btreim]

You're absolutely right, I mislabeled the second half of each pin. Here they are fixed. I'll double check that resistor when I get home tonight thanks for the tip!

TL072 -

1 - 4.97
2 - 4.97
3 - 4.55
4 - 0.00
5 - 4.96
6 - 4.97
7 - 4.97
8 - 9.38




4066

1 - 4.66
2 - 4.66
3 - 1.83
4 - 1.81
5 - 0.00
6 - 4.74
7 - 0.00
8 - 2.42
9 - 2.42
10 - 4.66
11 - 4.66
12 - 9.17
13 - 8.99
14 - 9.38


PT2399

1 - 4.97
2 - 2.48
3 - 0.00
4 - 0.00
5 - 3.10
6 - 2.48
7 - 0.86
8 - 0.90
9 -  2.48
10 -  2.48
11 - 2.48
12 - 2.49
13 - 2.49
14 - 2.48
15 - 2.47
16 - 2.48


TL072 -

1 - 3.03
2 - 3.13
3 - 4.97
4 - 3.00
5 - 3.01
6 - 4.97
7 - 3.13
8 - 3.63


2n5089

1 - 0.00
2 - 0.00
3 - 8.98

BC560B

1 - 1.05
2 - 0.56
3 - 0.00

7805

1 - 4.97
2 - 0.00
3 - 9.38

[btreim]

Hey Taylor,

You were right about the resistors. I swapped them out and now I'm getting modulation on the LFO and longer delay times. Only problem now is that I'm getting low leval distorted repeats. They seemed to be clean before I swapped the resistors, so I'm going to do some audio probing and make sure I didn't overheat the 2399 or something like that.

[btreim]

I was able to finish troubleshooting and get everything working properly. WOW what an amazing circuit! Thanks Ian and Taylor for what will be many hours of fun.

[Ginsengbob]

Hey Taylor and Slacker
Everything is working on my echo base but the modulation.
I took some readings and something is definitley not right.

Tl072 on the right side above the output


1    3.5
2    .1
3     5
4    .54
5    5.3
6    1.5
7    5.6
8    .01



4066


1       0
2       0
3       0
4       0
5       0
6       0
7       0
8      7.22
9       .05
10        .61
11      0
12      0
13      1.74
14       2.2




TL072    on left side everything is like you posted except

3          .01
5           7.2
7           1.5
8            .26

Any ideas where to start looking?

Thanks
Chris

[Ginsengbob]

ps
I checked the 220 ohm resistors and they were right.

[Taylor]

Hmm, I think maybe you've numbered the pins incorrectly - it should be like this:

http://upload.wikimedia.org/wikipedia/commons/thumb/b/b3/Pin_numbering_01_Pengo.svg/2000px-Pin_numbering_01_Pengo.svg.png

So take a second look with that in mind, but if I'm mentally transposing the numbers correctly, what should be your 9v rail is low, at ~7.2. Might start with investigating what voltage your power supply is giving you.

[Ginsengbob]

I'm looking from the top silk screen side with the square in the upper left of the ic pins.
I'm using a 9 volt battery that is a little low but when I started it was at around 8volts.
the battery was almost new when I started and I haven't had any response from the lfo section except that it affects the delay time.

[snarblinge]

This is normal, the lfo needs full voltage, I have built a few of these now, given up on battery as an option altogether.

[Ginsengbob]

I will try a proper power supply in the morning.
thanks

[petey twofinger]

just did two of these . i looked thru all the mods , but decided to go stock i guess .

i populated the boards , got sidetracked . finally did the wiring and it didnt work ... after 2 hours of toubleshooting , it was a single 10k i was short on . i was thinking i had left that out for a mod ... lol ... oh well , it fired right up no issue . i have to check the second one still but ... thanks for the great pcbs , i have done the christine , gristlizer and these , they all fired right up , pretty much ! lol .

i was gonna stick these in my noise box , but i am thinking i may pedal one , really nice sounding circuit !! - ( i am kinda echo snobby so ... )

now , to mod or not to mod . ? anyone care to save me some time and recomend the cool mods ( its  for noise ) for this ?

[Ginsengbob]

try the dub madness mod with a pot instead of the resistor.
experiment with different value pots for the feedback and time pots.

[Ginsengbob]

A 9v power supply raised the values a bit but still no modulation.


TL072 right side above output


1   4.28
2  .02
3  5.05
4  .69
5   6.63
6 1.66
7  5.05
8    .06



4066

8    9.44
9     .06
10   .8
13   1.79
14    2.35


Anybody have any ideas?

[Ginsengbob]

Sorry
i did the wrong ic pinouts

corrected

TL072 right side above output


1   4.28
2  .02
3  5.05
4  .69
5   .06
6  5.05
7 1.66
8   6.63






4066

8    2.35
9   1.79
12   .8
13     .06
14    9.44






Anybody have any ideas?

[Ginsengbob]

my led does not flash btw

[Ginsengbob]

Tl072 under lfo speed
pin 1 does not fluctuate from 4.28

[Ginsengbob]

my 2n5089


e   0
b   0
c    1.45

[Taylor]

The TL072's power (pin is still lower than I would expect. It should just be a bit less than your 9v rail.

You said you verified the 220R resistors. The one connected to pin 4 seems right but the one below it - can you measure the voltage on either side of it? Your 9v rail seems good since pin 14 of the 4066 is at 9.44v. On the left side of that lower 220R, you should also have 9.44v. On the other side it should be a little lower.