Sansamp Classic DIY - Problem

[animal]

Hi !!!!

I have a problem with the manufacture of this pedal, I followed this schematic and layout:




I have this problem that I try to explain in this video:

It is specifically in the sector of the TL072 when I activate option 3 of the DIP Switch, specifically the Low Drive. When the active happens the rare situation of cutting the signal, acting similar to a noise gate or a fuzz (I want to emphasize that all the rest works perfect, each option of the DIP switch works perfectly, except option 3), this affects the rest of the circuit mixing in the TL074 and finally the sound that comes out of the output presetna the same problem. When I do not activate option 3 the sound is perfect, everything works excellent, and in the Main Output the sound is as it should be, this confirms that the problem is not the TL074. Again, this only happens when activating option 3 in which a 10k resistor is added before the Amplifier Drive potentiometer, change all the surrounding parts, including the 10k resistor.
The only thing I used was a 2sk30A transistor, since I did not find the 2sk117.


HELP !

[Invertiguy]

Check all of the wiring going to the DIP switch and make sure nothing is shorting. I tried my hand at building one of these on perfboard a while ago and ran into so many problems from the wires on the DIP switch touching things they weren't supposed to that I ended up abandoning it and just designing a board for it in EAGLE with all the pots and the DIP switch moved on-board instead, and it made life a whole lot easier. Those switches really aren't meant to be wired off-board.

[slacker]

If you have a meter can you measure the DC voltage on pin 5 of the TL072 with switch 3 in both positions, it should be the same as the "bias" voltage.
Your English is excellent by the way

[aelling]

Dunno if it will solve your problem but in that layout 3 of pots look like they're backwards, VR2, VR3 & VR4.

Amp Drive should have lug1 to the 1k resistor and lug3 to the sw3 junction.
Output should have lug1 to pin12 of the TL074 and lug 3 to pin14 of the TL074.
High should have lug1 to pin14 of the TL074 and lug3 to pin13 of the TL074.

Using this lug numbering
http://4.bp.blogspot.com/-Eu1vuXVH3UM/TzGNIkeLuAI/AAAAAAAAAlM/h7re0CGH6A8/s1600/Pot20numbering.jpg

[DimebuGG]

Something is wrong with your wirings/connections. I have build these many times based from that schematic with no problems. In fact, I designed a pcb of that eliminating all those wiring connections. However, I designed it using SMD IC's and preferably 1/8W resistors,