I built a ts808 from tonepad. pcb from tonepad , parts from small bear. no mods all stock. bypass works good. when I turn pedal on volume drops alot( like going from 10 to 5). do have some clipping which sounds good. but no volume would have to turn volume up every time I turn on pedal.
Readings are
Q1
E-2.49
B -2.79
C -9.27
Q2
E -3.22
B -2.79
C -9.23
IC
p1 4.54
p2 4.7
p3 4.4
p4 0 Gr
p5 4.5
p6 4.5
p7 4.5
p8 9.1
Diode 1
k 4.7
A 4.5
diode 2
K 4.5
A 4.7
Diode 3
jumpered
I checked the pots for the right place
checked for bridging
checked for cold solder joints.
If I can get more volume I would be happy
Thanks
Welcome to the forum mate.
I think Q2 could be an issue. (this is not certain since you may have the wrong readings on B and E)
I'd expect the transistor emitter to be a diode drop (0v7) less in volts to the base.
more like your Q1 is.
Have a look around there for a bad solder joint maybe.
PS i think you misread the IC pinout too.
pin 8 should be +9 volts
not pin 5
IC pinout for dual op amps
https://arduino-info.wikispaces.com/file/view/lm293-n-pinout.jpg/328510794/lm293-n-pinout.jpg
OK I went back over solder joints and these are my readings now. using 9 volt batterry
q1
e 2.98
b 2.66
c 8.82
q2
e 3.04
b 2.67
c 8.80
io
1 4.38
2 4.56
3 4.30
4 0
5 4.37
6 4.38
7 4.37
8 8.79
d1
k 4.37
a 4.55
d2
k 4.55
a 4.37
d3 jumper
Pictures sometimes reveal all.
Quote from: whomeno on July 24, 2018, 04:55:20 PM
q1
e 2.98
b 2.66
q2
e 3.04
b 2.67
If your readings are correct you've back-biased transistors.. :icon_wink:
In case of mismatching E & B, Q2 seems to be OK but Q1 doesn't..
(unless Q1 is of Ge type.. :icon_redface:)
Considering +4.5V OK, check for 510k base bias resistor correct value..
what sort of transistors are they? howw are they connected? izz there a circuit dia?
and +1 photos, please.
schematic pdf
https://www.hobbielektronika.hu/forum/getfile.php?id=247049
i THINK the schematic has a "bug".
If you check the real schematic, it has a 2M2 res to ground from input.
Check my blue arrow:
(https://s33.postimg.cc/u9qyr97cr/image.png) (https://postimg.cc/image/u9qyr97cr/)
I'm building this same project this weekend, so i'll tell you how it goes :)
Quote from: Laguna on July 25, 2018, 04:48:54 PM
i THINK the schematic has a "bug".
If you check the real schematic, it has a 2M2 res to ground from input.
Check my blue arrow:
(https://s33.postimg.cc/u9qyr97cr/image.png) (https://postimg.cc/image/u9qyr97cr/)
I'm building this same project this weekend, so i'll tell you how it goes :)
Not a bug, it's a pulldown resistor to avoid pops when using true bypass switching. The schematic and layout are good. It was my first pedal build, actually.
Well, i built it and there's a farting noise and nothing else...
I spent a couple of hours trying to debug it and nothing.
I don't have a PCB, i wired everything by hand. I double checked and triple checked but probably still made a mistake. Would you recommend buying a printed PCB? any one in particular?
Thanks guys