Mudbunny green russian low volume

[Dave1992]

Hi guys! New to the forum here... I've just finished building a green russian mudbunny but the overall volume  and sustain of the effect is really low.
Anyone might have an idea what's the probleme here? ( I can post picture by request if could help)
Thanks!

[midwayfair]

Post voltages on all your transistors. And yes, pictures would help.

http://www.madbeanpedals.com/forum/index.php?topic=902.0

[selfdestroyer]

To add to Jon's post.

Did you use the 2n5088 transistors or something else? Remember that the silkscreen on the PCB for the transistors are for the 2n5088 and there is a chance that other transistors needed to be rotated. Check your pinouts of the transistors.

Cody

[Dave1992]

Hi guys! Thanks for the fast reply. So I've check for the reading but I'm probably doing it the wrong way: I've checked every leg of the transistor with the positive lead of my DMM & connected the common probe to the ground.  I didn't have any 2N5088 so I've use some 2N3904. The closest value I could find for C6 & C9 was 50n instead of the 47n and C10 is 4n7 instead of 3n9. I'll post better pictures when I'll de solder my home made pcb mounted pot.

So these reading goes as:
Q1 E: 0.56 B: 5.59 C: nothing
Q2 E: 0.53 B: 5.52 C: nothing
Q3 E: 0.51 B: 7.56 C: nothing
Q4 E: 5.26 B: 18.56 C: nothing

Pictures:
http://i1370.photobucket.com/albums/ag253/spacedave23/DSC_0023_zpsb978812f.jpg

[selfdestroyer]

Quick look at the datasheets for the transistors it looks like they are oriented the same way.

You could also test the resistance of the volume pot and make sure it is at about 100k fully clock wise.

I would also trim all the leads and maybe hit the back of the PCB with a tooth brush. All it takes is a copper strand to bridge something. If anything it will rule out the possibility of a bridge.

[Dave1992]

Hey! Just checked the pot value and it is in fact a 100K. I did as well clean it up but still, there is a big difference with my bypass signal :/ I can hear the sustain doing it's job, even though there is less gain than I was expecting, & the tone controle work as well. What about the reading with the transistors? Are they any good?

[selfdestroyer]

Hey! Just checked the pot value and it is in fact a 100K. I did as well clean it up but still, there is a big difference with my bypass signal :/ I can hear the sustain doing it's job, even though there is less gain than I was expecting, & the tone controle work as well. What about the reading with the transistors? Are they any good?

The voltages do not look right to me especially the base voltages. Hmm, maybe someone with more knowledge than I can help with this. I am not sure where to start probing around. Sorry.

Cody

[mmlee]

I might be wrong on this but it looks like its to do with your final stage (Q4) which is a simple make up gain stage after the tone section.  This would explain the low output volume but seemingly good sustain and tone controls.  Check the values of resistors around that last stage especially the ones on the collector and emitter as these set the gain.

Someone please correct me if I'm wrong.

Edit: This website should also help a lot to debug a muff.
http://www.electrosmash.com/big-muff-pi-analysis

Edit2: Get yourself an audio probe! You'll be able to check each section of a muff easily with it to find the 'bad one'.

[midwayfair]

People, people, he has NO voltage on his collectors. Anything else that could possibly be wrong is surely secondary to that?

Dave, you have to figure out why you aren't getting any DC on the collectors. First, verify that you're getting +9V at the DC input to the board and that it's 9V.

Next, set your multimeter to continuity. Got through the schematic very carefully and check continuity to everything connected to R24 -- and then make sure that those parts aren't connected to ground. Double check the orientation of D5 and C14. Make sure that all ground points are connected. Make sure nothing is grounded that shouldn't be. It's tedious, but while you're checking each part, you can also verify that it's the right value and in the right place using the build doc.

Your collector voltages should be about 6V, your base voltages should be a bit above 1V, and your emitter voltages should be about a half volt LESS than the base. (This last bit is a general rule, with very few exceptions, for bipolar junction transistors.)

[garfo]

You should have voltage on all you collectors.

[Dave1992]

hey guys! Sorry for taking so long, pretty busy with school right now & I'm dealing with some band issues but anyway... Had the time to check some stuff & there is voltage from R24 up to R17 but none in R19/C9 (so far that's were I'm at). Checking later on tonight & tomorrow. Be back in a flash

[Dave1992]

Hey guys, sorry for taking so long :s I've just checked back the board & I do have voltages reading on Q4 that goes E: 0.6 B: 0.03 Q: 8.46 and there is voltage on the main power rail ( R24, R12, R6, R22, R20, R17) I've notice though that there is no voltage on the thinner red lines (accord to the pdf doc.) So that might be were the probleme could be?

What do you guys think???

[mgwhit]

You can't read voltages off the traces -- they're masked over.  But I think your problem is your R22.  In your photo it looks like green-brown-black -- 51R!  It should be 10K (brown-black-orange).  That's totally throwing off the bias on your Q4.

[mgwhit]

You've done the same thing with your other two 10K resistors, R8 and R13, too.  Mislabeled bag?

And trim those wire strands, man!  From here it looks like your input, output and +9V are each within a hair's breadth of shorting to ground.

[Dave1992]

Yeah you're right... it was a mislabeled bag. So I've change R22 for a 10K & the other for a 12K (it was last thing I had lying around) but the reading on all four Q are all way off, max on all Collectors is about a 1v-1.2v.

Had to do some miracles as well since a I screwed a solder pad :/

http://s1370.photobucket.com/user/spacedave23/media/10754845_10152827332809798_363868283_n_zpsa08a02d4.jpg.html?filters[user]=141819916&filters[recent]=1&sort=1&o=0