tech12 bassdriver Debug

[guidoilieff]

I've made this one 3 times already but this time the clean signal wont work.

https://www.docdroid.net/thumbnail/wex6/1500,1500/tech12bassdriver.jpg Schematic.


The signal gets to the tl072 ic3b but at the output (pin 7) there is only hum.



Both tl074

1 4v
2 4v
3 1.66v
4 8v
5 3.15v
6 4.50v
7 4v
8 4.15v
9 4.20v
10 4v
11 0v
12 3.8v
13 4.15v
14 4.15v


Both tl072

1 4.15v
2 4v
3 4v
4 0v
5 4v
6 4v
7 4v
8 8v


Already swaped both tl072 and 74. Where do I go from here?

Thanks, sorry for my english.

[anotherjim]

If The IC's are in sockets, it could be contact trouble.

If IC3 pin5 has good signal, but nothing on Pins 6 or 7 then the link between 6 & 7 could be broken.

[Slowpoke101]

I assume that you have made your own printed circuit board for the project.
If you used the artwork that is included in the schematic that you posted be aware that there is an error with it.
The pad that SW2 connects to is not connected to anything. It must connect to the junction of C20 and R48.
That junction is the track that is closest to the SW2 pad.

Your voltages look to be OK (nothing obvious). So check your board for possible short or open circuit tracks.
If you could upload some pictures of both the component and copper sides it may be helpful.

[guidoilieff]

I assume that you have made your own printed circuit board for the project.
If you used the artwork that is included in the schematic that you posted be aware that there is an error with it.
The pad that SW2 connects to is not connected to anything. It must connect to the junction of C20 and R48.
That junction is the track that is closest to the SW2 pad.

Your voltages look to be OK (nothing obvious). So check your board for possible short or open circuit tracks.
If you could upload some pictures of both the component and copper sides it may be helpful.

Tested every pin for continuity and each adjacent pins to check for shorts. Everything seems fine.

Forgot to mention that the same thing happens with the balanced output.


If I could figure out where the "dry" signal path is I could work my way around.


The schematic is just for reference. I used another pcb that worked for me 3 times in a row without 1 problem.

[anotherjim]

Balanced can't work without the unbalanced.
Dry path is on the wire pad marked SW1.
SW2 pad is wet/dry according to the blend pot setting.