Hello eveyone !
I built a BSIAB 2 and it doesn't work :-[
I hear random explosions and weak guitar signal, there is no distortion...
The tone pot and the level pot somehow work, the drive pot only lowers the level as i turn it up.
I spent the whole day trying to fix it, but I couldn't find what the problem is.
I used the one from this site http://tagboardeffects.blogspot.co.il/2012/12/brown-sound-in-box-ii.html (http://tagboardeffects.blogspot.co.il/2012/12/brown-sound-in-box-ii.html)
it looks like this :
(http://2.bp.blogspot.com/-emz2HX7Bfq4/UQegKUUl9uI/AAAAAAAAEo8/YcBjtPJo44E/s1600/BSIAB+II+with+Contour+Control.png)
The voltages of the transistors are :
Q1
D=4.18
S=1.82
G=2.03
Q2
D=9.15
S=4.19
G=4.12
Q3
D=2.94
S=0.14
G=0
Q4
D=9.08
S=2.95
G=2.88
Q5
G=0
S=0.86
D=8.44
Do you have any idea what could be the problem ?
(https://preview.ibb.co/mXw3WT/Foto_20_05_18_19_25_23.jpg)
(https://preview.ibb.co/nJiLd8/Foto_20_05_18_19_25_26.jpg)
Thank you
Do you have a schematic that matches the layout you used?
There is one from General Guitar Gadget:
(https://preview.ibb.co/jm23Fo/ggg_bsiab2.png) (https://ibb.co/e0XQT8)
It doesn't include the Contour pot, which is connected to R7, and R7 value is changed from 47k to 5.6k.
It also has a diode D1 connected to V+
And Q3 Q4 are 2N5457 instead of J201's
- Ok for the pictures, but it's a bit hard to see well every parts. Try to take another look to the component's position by yourself. And another check to the interruptions track.
- I see some wires missing, but probably you soldered in the same stripe in the middle of the board, it could be ok, but I can't see the reason to do it like that. And I see a wire under Q1, I can't identify it. So check all the wires, those have to connect the right spots.
- Cut the board at the exact size of the board next time, it makes the work easier.
- The caps close to the q3 are 150pF and 470pF. Them seem to me pretty big, but I use ceramic caps with those values. Are you sure about those?
- Check the value of the resistors. Use the multimeter or compare them with some of the right value you could have in your stock.
- Pass a knife between the stripes if you see some contacts.
Quote from: Elijah-Baley on May 21, 2018, 03:38:28 AM
- Ok for the pictures, but it's a bit hard to see well every parts. Try to take another look to the component's position by yourself. And another check to the interruptions track.
- I see some wires missing, but probably you soldered in the same stripe in the middle of the board, it could be ok, but I can't see the reason to do it like that. And I see a wire under Q1, I can't identify it. So check all the wires, those have to connect the right spots.
- Cut the board at the exact size of the board next time, it makes the work easier.
- The caps close to the q3 are 150pF and 470pF. Them seem to me pretty big, but I use ceramic caps with those values. Are you sure about those?
- Check the value of the resistors. Use the multimeter or compare them with some of the right value you could have in your stock.
- Pass a knife between the stripes if you see some contacts.
Thank you so much !!! I used flat screwdrivier between the stripes and it works now :D
can you remeasure and post your fet voltages now that it works, please?
Q1
D=4.15
S=0.54
G=0.06
Q2
D=9.10
S=4.61
G=4.35
Q3
D=4.47
S=0.16
G=0.04
Q4
D=9.11
S=4.47
G=4.31
Q5
G=0.82
S=0.76
D=1.87
There is a high pitch sound that comes and goes now, even when the guitar volume is all the way down.
Q2 source and Q1 drain are connected and should be the same voltage.
Q5 gate should be 0.0x volts, yours is high for some reason. did you measure with no input signal? Q5 drain looks rather low for headroom, have you adjusted the trimpot?
I did measure it without input signal, is it wrong ? I never done this before.
And yea, the trimpot is adjusted.
no, always measure your voltages without an input signal. the static measures.