Yet another BSIAB II .... now with some pics

[Blues_Boy_4096]

Hi all !

I visit the forum almost every day, but just now I have finished my first build: a BSIAB II.

The voltages I get from the transistors are the following (as opposed to the ones at GGG):

Mine --- GGG

Q1

G- 0.00 --- 0.00
S- 0.52 --- 0.95
D- 5.22 --- 4.50

Q2

G- 3.98 --- 3.80
S- 5.22 --- 4.50
D- 8.35 --- 8.00

Q3

G- 0.00 --- 0.30
S- 0.07 --- 0.75
D- 4.17 --- 4.30

Q4

D- 8.35 --- 8.00
S- 4.17 --- 4.30
G- 3.97 --- 3.80

Q5

D- 1.22 --- 3.40
S- 1.01 --- 0.90
G- 0.00 --- 0.50

The sound I get is very fuzzy and with a lot of noise (which obviously increases as I turn up the gain or the volume)
All the pots have some effect on the sound, but it sounds bad whichever the setting is...

I have checked and rechecked all the wiring, and it seems allright...

What could it be ? Any help would be appreciated.

Thanks

[Ardric]

Q5

D- 1.22 --- 0.50
S- 1.01 --- 0.90
G- 0.00 --- 3.40

Are you sure Q5 isn't in backwards?  GGG says the drain should be at 3.4V, not the gate.

Do Q5's voltages change when you turn the trimpot?

[Blues_Boy_4096]

Q5

D- 1.22 --- 0.50
S- 1.01 --- 0.90
G- 0.00 --- 3.40

Are you sure Q5 isn't in backwards?  GGG says the drain should be at 3.4V, not the gate.

Do Q5's voltages change when you turn the trimpot?

It's in the correct position.
I just mistyped the values from GGG... (already corrected it)

Anyhow, this seems to be the one with the most divergent readings. Could it be the sole source of the problem?

[plucky]

Why does the drain isn't biased to 4.5v as in other projects??

[Blues_Boy_4096]

Do Q5's voltages change when you turn the trimpot?

Yes they do, except for the Gate, which is always zero.

[Ardric]

Do Q5's voltages change when you turn the trimpot?

Yes they do, except for the Gate, which is always zero.

Ok.  With the trim pot turned all the way to one side, Q5's drain resistor is 100k and you'd get a very low voltage at the drain of a typical 2n5457.  With the trimpot turned all the way to the other side, the drain resistor is 0 ohms and the drain should be at the same voltage as the power supply.  If by turning the trimpot you can't get the drain higher than 1.22V, then there must be something wrong with the trimpot or the way it's wired into the circuit.

By the way, is it the GGG board layout you're using?

[Blues_Boy_4096]

Ok.  With the trim pot turned all the way to one side, Q5's drain resistor is 100k and you'd get a very low voltage at the drain of a typical 2n5457.  With the trimpot turned all the way to the other side, the drain resistor is 0 ohms and the drain should be at the same voltage as the power supply.  If by turning the trimpot you can't get the drain higher than 1.22V, then there must be something wrong with the trimpot or the way it's wired into the circuit.

By the way, is it the GGG board layout you're using?

Done that.
With the trimpot to one side, I get 0 V on the drain, to the other I get near 9 V. I left the trimpot in a position where I get 3.46 V on the drain. The other two values never change.

And yes, I'm using GGG's board

[Blues_Boy_4096]

IT WORKS !!!!

It's ALIVE !!!!

I was going to start probing the board this afternoon, and the problem was gone...

I don't have the slightest clue what the problem was, neither did anything to solve it (except for adjusting the trimpot to get the right value on Q5, which didn't change the sound)

Go figure.....

Thanks everyone for the prompt assistance. You guys are great !! 

Tomorrow I'll post some pics of the pedal.

[Blues_Boy_4096]

Here are the pics:

[Bucksears]

Looks NICE, Blues_Boy!!!
Ok, how are you people doing the white lettering on colored boxes?? I'm still doing white boxes and a regular label on top.
- Buck

[Ardric]

That's a really nice looking box!  Congrats on getting it working.

Is that pink foam under the circuit board the stuff that they ship computer motherboards with?  If it's anti-static foam, it's slightly conductive, and it may have been the cause of the problems.

[BN]

Ok, how are you people doing the white lettering on colored boxes??

I'm also curious about that. Really nice looking box!

[Blues_Boy_4096]

Is that pink foam under the circuit board the stuff that they ship computer motherboards with?  If it's anti-static foam, it's slightly conductive, and it may have been the cause of the problems.

Yes it is... I think you found the problem....maybe that was why it didn't work in the first place, although the foam is still there and it's working, but...

OK, how are you people doing the white lettering on colored boxes??

I'm also curious about that. Really nice looking box!

For the lettering I used self-adhesive vinyl, cut in a vinyl cutting plotter.
After sticking it to the box, I applied some layers of clear coating spray... and voila...

[BN]

For the lettering I used self-adhesive vinyl, cut in a vinyl cutting plotter.

I wish I had one of those plotters...   

Thanks for the answer anyway

/BN

[cakeworks]

For the lettering I used self-adhesive vinyl, cut in a vinyl cutting plotter.
After sticking it to the box, I applied some layers of clear coating spray... and voila...

This vinyl cutting plotter of which you speak... is it somewhat similar to a large printer but it cuts shallow marks in sheets of vinyl?

[bancika]

I do mine with vinyl too. There's local company that does custom cutting jobs. I can get stickers for 5 pedals for less than a $

[Pushtone]

SWEEEEEEEET! My favorate color combo, blue and white!

about the vinyl art...

Those thin lines around the perimeter and the circles around the switch look perfect.
Are you saying you peeled them off a sheet and then applied them to the top?

I would figure they would be pretty hard to laydown straight without distorting the shape.
They look so thin and spindly, fragile.

Is there more to it than that?

I can imagine placing a whole sheet of scored vinyl down and then
removing the negative spaces to get that kind of accuracy.

You should post the pic in the Pictures thread so it's preserved for all time.
Like AC/DC sang... "Forget the hearse cause I'll [the picture thread] will never die! 

[Eric H]

That's a really nice looking box!  Congrats on getting it working.

Is that pink foam under the circuit board the stuff that they ship computer motherboards with?  If it's anti-static foam, it's slightly conductive, and it may have been the cause of the problems.

Good eyes.

-Eric

[bancika]

Pushtone, I don't know how he did it, but there's transfer foil which is adhesive. You put it on vinyl, press hard and then remove it. Vinyl stays on foil cause it's adhesive and now you only need to stick it to destination, press hard again and then remove transfer foil. Vynil adhesive is stronger than foil's, so vinyl remains on target and only foil peels off. Ingenious