Hi,
First time writing the forum...
I'm building a Foxx Tone Machine using a Musikding PCB.
Almost got no sound.
With audio probe i have sound from Q2 collector to the end of the circuit. Gain, octave, tone... everything seems to work from this point.
The voltages are really crazy but i don't know whats wrong.
Changed the transistors but same problem.
I checked values and solder joints and looks OK (but something is not OK ;-)
v=9,48v
Q1
C: 5.45V
B: 4.7mV
E: 0.0mV
Q2
C: 4.88V
B: 5.45V
E: 7.77V
Q3:
C: 7.43V
B: 0.840V
E: 0.207V
Q4
C: 8.17V
B: 0.810V
E: 0.198V
Thanks in advance
Ramiro
Welcome, Ramiro.
Do you have pictures of your build - top and bottom?
BTW, here's a copy of the Musikding schematic for anyone who needs to see it:
(https://i.imgur.com/iSnrziA.png)
(https://i.postimg.cc/NLc6ZY1S/IMG-20190312-191155502.jpg) (https://postimg.cc/NLc6ZY1S)
(https://i.postimg.cc/D46yM1qv/IMG-20190312-191220567.jpg) (https://postimg.cc/D46yM1qv)
(https://i.postimg.cc/LnmJ38z4/IMG-20190312-191243976.jpg) (https://postimg.cc/LnmJ38z4)
I don't get it. T2 emitter volts shouldn't be higher than its base or collector. The only way I can get that is to reverse the power supply polarity to the board or have a short circuit to the + supply somewhere connecting to the emitter.
I tested the diodes before just to know the rigth direction. One OA1182 broke while i was bending the leg. I put a D9K with the same voltage drop.
I used to socket the diodes but i didn't have more terminal strip at the moment....
D1 seems to work fine.
I think the problem is in the R3-4-5-6-8-C2-3 network....
Thanks for your answers
QuoteI think the problem is in the R3-4-5-6-8-C2-3 network....
look very,
VERY closely at R6. is there a yellow band on it?
:icon_redface:
It's a 100 Ohm insted a 100k...
I'll replace It and write Tomorrow...
Thanks
That's was the problem....
Now it's working OK.
Sorry for the silly mistake and thanks for the replies.
easy. excellent. and, you picked out the problem area yourself, didn't need us at all.