Echo Base Music PCB Troubleshooting

[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.

[slacker]

Is the volume of the signal on pin 12 louder than the input signal? If it is but the signal on pin 14 is faint then I would check the values of the resistors connected to pins 12, 13 and 14 if one of those was wrong it could lead to a quite signal on pin 14. Also check for any shorts between pins 13 and 14.

I'm sorry I can't remember which way round the pots go, if the level and feedback and the speed of the LFO (speed the LED flashes) increase as you turn the pots clockwise then they are the right way round.

[Misterwinefine]

Slacker thank you for your response, I will double check that this evening and get back with you.  I believe the wiring on the pots is correct based on your response the Led responds to the clockwise turn of the the speed it does increase. 

[Misterwinefine]

Slacker, Your a great guy to help all of us out trying to build this gem.  You have to get tired of all the questions, my hats off to you.

I have checked every connection and all components from pin 16 through Pin 1 of the Pt 2399 and found no error.  I have the input volume as same as the output volume as 12.  14 is faint out of PT 2399 and going into the 4066 on pin ten it is very faint following the schematic through.  Could I have an error in 4066?

The Voltage readings
PT 2399
1.  4.96     16.  2.48
2.  2.48     15. 2.50
3.   0         14. 2.48
4.   0         13. 2.48
5.   2.91    12.  2.50
6.   2.48     11.  2.48
7.  0.755    10.   2.48
8.   0.766    9.   2.50

Readings on the
4066
1.  4.46                     14.  8.95
2.  4.46                     13.  8.75
3.  1.42  changes        12.  8.57
4.   0.137 changes       11. 4.69
5.  0                           10.4.69
6. 4.31                       9.  2.50
7.  0                           8.  2.50  I read somewhere when you have a large resistor in line these readings could be off due to the DMM.  8 and and 9 have very large resistors in line here.

2n5089

0   E
0   B
8.59  C  Effect on

Audio TL072
1.  4.78    8.   8.95
2.  4.78    7. 5.17
3.  4.36    6. 4.97
4.  0        5. 4.96

Is it possible I have something messed up with the Audio IC it appears correct and i have changed it out for another one.

I forgot how to post an image that might help if I can remember how to do it.



Still Stumped!

[Misterwinefine]

Fixed the faint signal issue a hairline crack in a resistor audio probe a great help, unfortunately now I have issues with the op amp and I think a socket that will not hold getting a lot of static. Back to the debugging process.  This his been an elusive build so far.

Sad part of it is it was working until I got the bright idea to replace the I with a fresh one now problems.