Fulltone Bassdrive Mosfet NO SOUND

[hyperliteBo]

Hey all, I build this and I got no sound at all, triple checked the schematic, checked all my solderjoints, checked for unwanted bridges, checked, checked, checked.
Here are my volatages and pictures, any help would be appreciated :/

IC


Q1  
E: 2,71v
B: 2,25v
C: 9,14v

Q2  
E: 2.67v
B: 2,22v
C: 9,14v

Q3
S: 0,69v
G: 0,32v
D: 0,32v

Q4  
S: 1,40v
G: 0,95v
D: 0.95v

[aelling]

Looks like you have hot input signal to ground on the input jack.
http://beavisaudio.com/techpages/stompboxwiring/

[hyperliteBo]

Euhm no I think you're seeing that wrong, I should also add, signal is getting trough when pedal is bypassed.
Also, I updated the IC voltages, think my numbering was a bit wrong.

[aelling]

I see, it's a switched jack.

I saw Johnk mentions there shouldn't be 8,52v at pin 1, so I looked at the board and it looks like the track between pin 1 & pin 8 might not be cut completely.

[hyperliteBo]

Yes found that on out myself literally 15 mins ago and fixed it, progress but new problems arise !

I have sound now but volume is really low(but working reacting),even below unity when maxed out, boost seems to add more dirt turned clockwise but also lowers volume quite a lot when doing so.
SPST switch for mosfet/standard does nothing.
Tone seems to work, so does the on/on/on CFV switch


All new voltages now though...



Q1  
E: 3,6v
B: 2,87v
C: 9,14v

Q2  
E: 3,54v
B: 2,82v
C: 9,14v

Q3
S: 3,71v
G: 3,23v
D: 3,23v

Q4  
S: 4,54v
G: 4,05v
D: 4,05v

Is it possible that the IC or on of the transistors are damaged now ?

[aelling]

The only thing I see now is the wire from Drive 1 on the board, you have going to Drive 3 on the pot. Drive 3 should not be connected to anything.

[hyperliteBo]

Yeah sorry, found that one as wel already, didn't update the original picture :/
I also rewired the ON/ON/ON switch because it wasn't doing anything and I figured I had a different type (stupid that there are two :p)
So yeah rechecked everything again and all seems fine but still...

[aelling]

Okay, so now that you have sound, what is the problem? What is working and what is not? Also, what IC/transistors are you using?

[hyperliteBo]

Still the same of some posts above.
Volume is really low(but working reacting),even below unity when maxed out, boost seems to add more dirt turned clockwise but also lowers volume quite a lot when doing so.
SPST switch for mosfet/standard does nothing.
Tone seems to work, so does the on/on/on CFV switch

I really appreciate your help btw, I made many builds and this I just can't figure out.

[aelling]

I see, okay.

For the clockwise working boost pot, just take the wire from lug 1 and solder it to lug 3.

From what I can tell by looking at the schematic, CFV sw4 should not go to Drive 1 but actually pin 2 of the IC, easy to do just take the wire from the pot and move it to the strip under where Drive 1 connects to the board.

Bassdrive schem
https://www.talkbass.com/attachments/bassdrivemosfetschematic-jpg.2005067/

Lastly the 150K on the Bassdrive schematic is actually a 47K, and 150K on the Fulldrive II so they're swapped on those layouts.

Bassdrive layout
http://2.bp.blogspot.com/-_eY8FPjE2dQ/U2DM1UuEHvI/AAAAAAAAG-s/UYs6Bybq6Vg/s1600/Fulltone+Bassdrive+Mosfet+ver+4.png

No problem, I have nothing better to do

EDIT: I see others mentioning on the main site that the jumper that goes from Q4 Source to pin 2, should actually go from Q4 Source to pin 1. That's also something I see in the schematic.

[hyperliteBo]

Alright!!
Now we're getting somewhere !
As the post was labeled verified I assumed both version were... but after checking the schematic myself (I have limited skills) it seems they aren't
I bridged to pin 1 instead of two and changed the 150k to 47k resistor.
Getting usable sounds now at least :)
Now there are only two things that don't work, I hear no difference between FM mode and Vintage Mode, I do however between FM Mode and Compcut, and I hear no difference between Mosfet and Standard toggle.
Could this be that I in the end do have the "wrong ON/ON/ON switch?
Mine behaves like type 1:



Also one small thing, when volume is above 60-70% it starts to decrease back a little bit, almost like hitting a limiter or compressor too hard, wondering if this this normal behavior of the pedal or a fault :/
Doesn't bother me too much since there is enough volume but still wondering.

Again, thanks for all the help, funny though, it's the second time I couldn't figure it out myself, and it's the second time it was because of a wrong vero drawing

[aelling]

Nice!

Yes, IvIark explained about the switch differences in the comment section on the main site as well. So swap the wires to what he mentions below and report back.

IvIark27 April 2014 at 01:58

Just a heads up for anyone building this after Brownpedals comment on the Fulldrive thread. Before you build it, check that the contacts on the CFV switch behaves in the following way before soldering it up. The way it is drawn requires 2 & 3 and 4 & 5 to be made in the centre position. If that isn't the case with the ones you buy and instead 1 & 2 and 5 & 6 are made in the middle position, then swap over the poles so:

Lug 1 becomes 4
Lug 2 becomes 5
Lug 3 becomes 6
Lug 4 becomes 1
Lug 5 becomes 2
Lug 6 becomes 3

[hyperliteBo]

Soooo, I think I got basically everything figured out...
I changed the wiring of the ON/ON/ON switch but things weren't quite right yet, then I saw that in version one (the one I guess was verified) that CFV Sw4 goes to to IC pin 2 and on the second (unverified version?) It says that CFV Sw4 is connected to drive 1, which is again connected to IC pin 1...
So I changed that (see pic below) and it seems to be fine now.



Only one small thing that remains, from what I read in the manual, the Mosfet/Standard switch seems to does the opposite so Sw1 and Sw3 might be reversed in both layouts?

Too bad the vero is called verified because it very clearly isn't :/

Anyway, got it working in the end, thanks a lot for your help and patience, I appreciate it a lot !

[aelling]

Nice, glad you got it working, happy to help. For the reversed mos/std switch, just flip the switch around, no need to swap wires.

There's probably a whole bunch of verified layouts that actually isn't a working layout, if it's not build and verified by someone as time goes by people just forget about it and/or just don't have time to fix it.