The Tone God - Forsaken

[Alex]

Original project: http://tech.thetonegod.com/forsaken/forsaken.html
Reversed pots orientation but not sure if correct.
Sensitivity could be a trimmer?

[Hozy31]

You are the man Thanks Alex. Might give this a go tomorrow if i have any BS250s.

[Hozy31]

Ok, Built this but don't have any BS250s. Had a look for alternatives but didn't really find anything i recognised. Anybody know what i could use to see if this is working?

EDIT: Found a couple of BS250s at the bottom of my transistor stash after a thorough search through. Not getting much from it. If i put a signal before it i get nothing coming out and with a signal after i get a grounding sound when i press the metal plate. If i touch the metal plate and then touch a guitar string it all goes silent again. If i turn the volume way up i can hear very faint guitar signal in the background but only with a really high gain pedal after it. Done the usual debugging. Did notice the voltages of my opamp and some of the transistors give unusual readings, see below.
source voltage 8.24v
TL072
1 - 0
2 - 3.89
3 - 120mv
4 - 0
5 - 6.94
6 - 0
7 - 6.94
8 - 8.24

Top BS170
D - 8.17
G - 100mv moving to 400mv when plate touched
S - 0

5089
C - 6.72
B - 0 to 300mv when plate touched
E - 0

Bottom BS170
D - 0
G - 7.64
S - 0

BS250
D - 8.24
G - 8.24
S - 7.65

Right mid BS170
D - 8.24
G - 0 to 3.81v when plate touched
S - 8.24

[Alex]

There's something wrong with the IC's voltages.
Pins 1 & 6 seem to be grounded.
Have you tried to re-flow the solder under the IC socket? Checked all cuts? Drive Pot working properly?

[Hozy31]

Yes i thought that wasn't right. I will try reflowing when i'm back from work. I don't think the drive pot was doing anything if i recall. Had a good check of the cuts as i have had problems with flecks of copper in the past. I will try and debug further later today. Could be a dodgy ic, but i've never had a dodgy 072 before.

[Hozy31]

Ok so reflowed everything, swapped out ic for another, checked all transistors on my tester, checked pots and all seems good. Don't understand. I am using a scrap bit of one sided copper for the plate.

[Alex]

Double checked it again and layout matches the schematic.
Not many infos about this project.
I've just found a sound sample on DIY ( http://www.diystompboxes.com/smfforum/index.php?topic=54786.msg420208#msg420208 )
Have you tried disconnecting Drive 1 and jumpering Pins 1 & 6?
Can't understand why they seem to be grounded.
On another subject: did you manage to test the Funny Cat with the extra boost?

[Hozy31]

What do you mean by jumpering pins 1 & 6?

Sorry, not got round to that yet. I might get the chance tonight or tomorrow night though. I'll reply back on the funny cat post when i'm done. Tonight might be tough to get it done as i just received a package of 3522 transistors of various quantities and values, so need to cataloque and check. Good old ebay, sometimes the bargains astound me.

[Alex]

Pins 1 and 6 (IC) seem to be grounded on your Forsaken voltages.
They go to Pins 2 & 3 of the Drive pot.
Pin 1 of the pot goes to ground.
If you disconnect pin 1 and link together pins 2 & 3 of the pot (pins 1 & 6 of the IC) the drive should be at max.
Just wanted to know if their voltages would change after doing that.

[Hozy31]

Tried that and voltages at ic pins 1 & 6 are still 0. However, now when i touch the plate i get a nice tone which doesn't change when rotating the pots, but only with a really high gain pedal in front. On its own its totally silent. .

[Alex]

Unless there's a mistake in the schematic I can't think of anything else.
I can't breadboard it cause I don't have any BS250s or possible substitutes.