EchoBase LFO not working

[Papipone]

Hi,

I recently build an EchoBase. I used the PCB sold by MusicPCB. Everything worked well, but when I plugged back the pedal, I lost the LFO modulation. So, LFO dept, LFO speed and LFO waveshape are not working anymore.
I first checked my power source (9v) --> no problem. I next checked the values beetween the LFO Depth and the PT2399. Resistors do not appear to be faulty but I do not know if i get the right values (Volts) in this area.
Everything is oscillating (don't remember the exact values. I will post it if someone ask), which i think is normal, between the base of the BC560 (the one routed to the 3rd and 4th lugs of the PT2399) and the others components situated at right of the delay chip (OpAmp, pots, resistors ...).
I also checked the continuity, everything seems to be good.

If someone could help me ?

Thanks.

[Mario44]

Welcome to the forum and Hi
I had quite similar problem with LFO. After checking all audio probing and measuring voltages etc... finally got changed pots. After that lfo started working.
Is the BC560 oriented right? If you can post voltages, it always helps to find out the problem more.

[Papipone]

Thanks for the response. I think that the bc560 is well oriented ( or should, ı will check it). I am currently leaving my workplace, i post the values when i come back home.

[slacker]

Is the LED flashing or just constantly on?

[Papipone]

Hi,

Insert Quote
Is the LED flashing or just constantly on?

Yes, the led is flashing, depending on the LFO Speed pots position.

Here are my values :

TL042 OpAmp :
    - 1 : Oscillating between 3,8 and 5,9V
    - 2 : 5V
    - 3 : 5V
    - 4 : Oscillating between 0,750 and 0,850V
    - 5 : Oscillating between 4,40 and 6,10V
    - 6 : 5V
    - 7 : Oscillating between OL (Out of Limits (bug of my multimeter ?)) to 10V
    - 8 : 8,5V

LFO Speed :
    - 1 : Oscillating between 4,70 and 5,20V
    - 2 : Osillating between 4,80 and 5,20V
    - 3 : Oscillating between OL (Out of Limits (bug of my multimeter ?)) to 10V

LFO Depth :
    - 1 : 0V
    - 2 : Oscillating between 66 and 130mV
    - 3 : Can't read the values (moving too fast). Oscillating in mV.

BC560 :
    - B : Oscillating between 80 and 140 mV
    - C : Oscillating between 0,560 and 0,670 mV
    - E : 0V

[Papipone]

Up 

[Mario44]

I see TL042 first time in this effect and I wonder if pinouts are correct. In my version I used TL072.
Here is quote from slacker's echo base thread(rly long one ). A link: http://www.diystompboxes.com/smfforum/index.php?topic=60662.60 and a quote:

To help with the debugging here's some voltages and other info that we found useful when me and Mike F were debugging his.

PT2399
1. 5v
2. 2.5v
3. 0
4. 0
5. 2.89v
6. 2.5v
7. 0.5v
8. 0.5 v
9 - 16 all 2.5v

4066
Some of the voltages change depending on if the effect is on or bypassed (off) so I've shown the voltages for the different states.

1. 4.6v
2. 4.6v
3. 0.4v
4. 0.4v
5. 0
6. 0.45v off 4.5v on
7. 0
8. 9v
9. 3v on 0.32 off
10. 4.6v
11. 4.6v
12. 8.5 on   
13. 8.5 on
14. 9

When the effect is off depending on which position the tails/Boss switch is in either pin 12 or 13 will be 1.25v the other will be about 8.7 volts.

The TL072 voltages are

U3 top left of vero

1. 5v
2. 5v
3. 5v
4. 0
5. 5v
6. 5v
7. 5v
8. 9v

U1 bottom left of vero, this is the LFO

1. changes
2. 5v
3. 5v
4. 0.8v
5. changes
6. 5v
7. changes
8. 8v

The voltages on the 5089 should change depending on the position of the bypass switch.
E. 0
B. 0.63v off 0 on
C. 0.89v off 8.5v on

These are audio probe results from the PT2399

16. very quiet signal
15. delay
14. loud delay with cyclic noise
13. nothing, or possibly a very quiet signal
12. delay with hiss
11. very quiet delay with hiss
10. very quiet delay with hiss
9 . delay with cyclic noise and hiss

It's all I can do for now.

[Papipone]

I see TL042 first time in this effect and I wonder if pinouts are correct.

I made a mistake. I used a TL072.

[slacker]

   - 3 : Can't read the values (moving too fast). Oscillating in mV.

Something could be wrong here, it should be oscillating something like 2 volts at the same speed as the LED is flashing. Have a look at this post and the ones after it for someone with a similar problem.

http://www.diystompboxes.com/smfforum/index.php?topic=84109.msg953958#msg953958