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! :)
Post voltages on all your transistors. And yes, pictures would help.
http://www.madbeanpedals.com/forum/index.php?topic=902.0
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
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
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.
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?
Quote from: Dave1992 on October 30, 2014, 12:56:00 AM
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
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'.
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.)
You should have voltage on all you collectors.
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 ;)
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???
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.
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.
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
Is it working properly now?
Not so far :/
Check your caps....
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First, make sure you have no soldet bridges. Then, one by one, Check all your resistors to see If they are the right value. If necessary use your DMM, then Check the caps. If you have Sound coming out, something might be misplaced. Also chech the transistors. Do some pinout comparissons in case you replaced trainies.
Hey guys, just managed to clean the board with some isopropyl alcool & the board started working correctly. Maybe there was a tiny bridge somewhere. Anyway thanks for the help, really appreciated! :)
I had the same problem with a vero layout Muff, low volume even with the volume maxed out. DMM showed I had normal voltage on all transistors. Using an audio probe I noticed that I had good signal until after Q3, with the problem being in the tone stack. The signal going to lug 1 of the tone pot was good, but the one going to lug 3 was fizzing out. Turn the tone knob fully CCW and you had volume, start turning it CW and the volume went down. I'm still not sure what happened but the signal degraded after the 3n9 cap. Oddly enough if I disconnected the output from that cap (so just input, output end sticking out in the air) to see if the cap was bad the signal was okay. Solder it back into the circuit and fizzing out again. I tried desoldering the grounding resistor and lug 3 and only with them both gone did the signal volume turn good again. Really weird. Still not sure what went wrong. I made a new vero board and populated it with new components and now it works as it should.
Ok guys so me again... Took the time to sit down and play with the pedal and there is something else that I didn't notice the first time around: depending on where the tone knob is set there's a weird pulsating sound ( treble side) or a kind of woosh (bass side)
So I've checked some other reading on the board:
R6, R12, R17, R20, R22, C14 and C15 all read 9V (or so)
I also did check the voltage reading on C2, C3 are reading 1,18V
C5, C6, C8, C9 also read 1,18V but 0,02V on the diode side.
C1, C4 read 0,03V
C11 is reading 0,37V
& C13 read 0,97V
Should it be reading these voltages or are they wrong???
Any one???
Quote from: Dave1992 on December 11, 2014, 07:28:29 PM
So I've checked some other reading on the board:
R6, R12, R17, R20, R22, C14 and C15 all read 9V (or so)
I also did check the voltage reading on C2, C3 are reading 1,18V
C5, C6, C8, C9 also read 1,18V but 0,02V on the diode side.
C1, C4 read 0,03V
C11 is reading 0,37V
& C13 read 0,97V
Should it be reading these voltages or are they wrong???
It would be much more helpful for you to post your transistor pin voltages. I'm guessing your Collector voltages are too low.
Yes, the collectors are too low
Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5
They used to be even lower though
Quote from: Dave1992 on December 22, 2014, 10:19:38 PM
Yes, the collectors are too low
Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5
They used to be even lower though
Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?
Quote from: midwayfair on December 22, 2014, 10:41:29 PM
Quote from: Dave1992 on December 22, 2014, 10:19:38 PM
Yes, the collectors are too low
Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5
They used to be even lower though
Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?
That's the part I don't get as well... I've checked both bias resistor & they do in fact read 12k each. The emitter read 390R as it should... Any idea what might be causing this? Is the reading on Q1,2 & 4 any good though?
Quote from: Dave1992 on December 22, 2014, 11:16:46 PM
Quote from: midwayfair on December 22, 2014, 10:41:29 PM
Quote from: Dave1992 on December 22, 2014, 10:19:38 PM
Yes, the collectors are too low
Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5
They used to be even lower though
Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?
That's the part I don't get as well... I've checked both bias resistor & they do in fact read 12k each. The emitter read 390R as it should... Any idea what might be causing this? Is the reading on Q1,2 & 4 any good though?
Check all the resistors connected to that transistor. replace them if you have to. When you say "reads" are you using your eyes or a multimeter? Your eyes are very bad at telling you how many ohms something is.
Quote from: midwayfair on December 23, 2014, 12:46:01 AM
Quote from: Dave1992 on December 22, 2014, 11:16:46 PM
Quote from: midwayfair on December 22, 2014, 10:41:29 PM
Quote from: Dave1992 on December 22, 2014, 10:19:38 PM
Yes, the collectors are too low
Q1 read 0.12;0.76;5.14
Q2 read 0.11;0.75;5.77
Q3 read 0.75;1.38;6.20
Q4 read 0.11;0.75;5
They used to be even lower though
Q3 is wrong. Look at the schematic -- it has the same parts and biasing as Q2. So how can its biasing be SO significantly different? How can its emitter voltage be so high if there's only a few hundred ohms there?
That's the part I don't get as well... I've checked both bias resistor & they do in fact read 12k each. The emitter read 390R as it should... Any idea what might be causing this? Is the reading on Q1,2 & 4 any good though?
Check all the resistors connected to that transistor. replace them if you have to. When you say "reads" are you using your eyes or a multimeter? Your eyes are very bad at telling you how many ohms something is.
I'm using a dmm. So I've checked the resistors on all four Q & they are all good except R3,9 and 14 wich read 38.8K instead of 100K and R21 81K instead of a 100 as well.
I'll go buy new resistors this week and see if that does the trick! Could the probleme be there???
Testing resistor values once they're connected into a circuit is almost never going to produce accurate results, though. I'd pull them, test them out of circuit (if only to identify the problem) and then replace them with known good parts (i.e. measured beforehand). I'd also check out Q3 itself while you're in there swapping out parts. I'd think there's a much grater chance of having a bad transistor than a bad resistor, but who knows.
I'd also consider audio probing the circuit to see where the whooshing sound starts.
I just did the exact same project with the exact same problem.
Can you post the color code of the resistor you have in R24?
I accidentally had a 100k resistor there instead of a 100R resistor.
-C
edit:corrected nomenclature
I can't make that emitter bias happen with ANY of the correct values or anything resembling their markings. I even tried swapping resistors around if you happened to have them in the wrong place.
Try just grounding the emitter. If it doesn't get really loud, then it might be a bad transistor.
Quote from: hubb on December 23, 2014, 02:57:15 AM
Can you post the color code of the resistor you have in R24?
I accidentally had a 100k resistor there instead of a 100R resistor.
If it's still the same as it was in the original photo, it's brown/black/brown/gold for 100R.
Quote from: hubb on December 23, 2014, 02:57:15 AM
I just did the exact same project with the exact same problem.
Can you post the color code of the resistor you have in R24?
I accidentally had a 100k resistor there instead of a 100R resistor.
-C
edit:corrected nomenclature
It's brown/black/brown/gold & my dmm read 100R
So I've checked all the 100K resistor (unsolder a lead to test them) and they all are 100K
Also I've notice that Q4 is the one with the higher reading, not Q3 ( my bad). I've said earlier in this post that I have a DC reading in the tone pot, lug 1 and 2 read 4. 10-40V and lug 3 read 1v and just a bit more. I don't know if it's normal or not, might me the reason why the strange hiss/woosh in the tonestack.
You do you guys think?
Quote from: Dave1992 on December 23, 2014, 09:39:44 PM
So I've checked all the 100K resistor (unsolder a lead to test them) and they all are 100K
Also I've notice that Q4 is the one with the higher reading, not Q3 ( my bad). I've said earlier in this post that I have a DC reading in the tone pot, lug 1 and 2 read 4. 10-40V and lug 3 read 1v and just a bit more. I don't know if it's normal or not, might me the reason why the strange hiss/woosh in the tonestack.
You do you guys think?
I still don't know how your emitter can be that high with a 390R, but the numbers are more normal for Q4 at least.
Maybe I missed it, but have you audio probed to see where you're actually losing signal?
There should be DC in the tone pot. There's no capacitor between C3 and Tone 1.
Quote from: midwayfair on December 23, 2014, 10:23:53 PM
Quote from: Dave1992 on December 23, 2014, 09:39:44 PM
So I've checked all the 100K resistor (unsolder a lead to test them) and they all are 100K
Also I've notice that Q4 is the one with the higher reading, not Q3 ( my bad). I've said earlier in this post that I have a DC reading in the tone pot, lug 1 and 2 read 4. 10-40V and lug 3 read 1v and just a bit more. I don't know if it's normal or not, might me the reason why the strange hiss/woosh in the tonestack.
You do you guys think?
I still don't know how your emitter can be that high with a 390R, but the numbers are more normal for Q4 at least.
Maybe I missed it, but have you audio probed to see where you're actually losing signal?
There should be DC in the tone pot. There's no capacitor between C3 and Tone 1.
I don't have an audio prob & don't have access to one unfortunately :/
Wich emitter are we talking about at this point since Q4 seem to be more normal? At R23 I have a 2k7 instead of a 2k (couldn't find any at my local shop)
Quote from: Dave1992 on December 23, 2014, 10:49:56 PM
I don't have an audio prob & don't have access to one unfortunately :/
Have you read Jacob's instructions in the tech help rules thread for creating an audio probe? It's literally a capacitor and a cable. I just use alligator clips, so I don't even have to destroy a cable.
MAKE ONE! They're dead easy to make (I followed the instructions from the BYOC confidence booster kit) and I cannot troubleshoot without it. Making one was one of the best decisions I ever made as it allowed me to halve my pile of non-working pedals.
You don't even need to destroy a cable. Two alligator clips, a capacitor, a female mono jack and some wire like you use inside pedals is all you need.
Quote from: midwayfair on December 24, 2014, 02:19:17 AM
Quote from: Dave1992 on December 23, 2014, 10:49:56 PM
I don't have an audio prob & don't have access to one unfortunately :/
Have you read Jacob's instructions in the tech help rules thread for creating an audio probe? It's literally a capacitor and a cable. I just use alligator clips, so I don't even have to destroy a cable.
No I haven't, can you send me a link for it?
Merry Christmas btw guys ;)
Quote from: Dave1992 on December 25, 2014, 05:16:42 AM
Quote from: midwayfair on December 24, 2014, 02:19:17 AM
Quote from: Dave1992 on December 23, 2014, 10:49:56 PM
I don't have an audio prob & don't have access to one unfortunately :/
Have you read Jacob's instructions in the tech help rules thread for creating an audio probe? It's literally a capacitor and a cable. I just use alligator clips, so I don't even have to destroy a cable.
No I haven't, can you send me a link for it?
Merry Christmas btw guys ;)
It's the tech help rules thread. It's the sticky in the tech help section. It's required reading ;) Actually, this thread should be there, I'll ask to have it moved.
Quote from: midwayfair on December 25, 2014, 02:44:18 PM
Quote from: Dave1992 on December 25, 2014, 05:16:42 AM
Quote from: midwayfair on December 24, 2014, 02:19:17 AM
Quote from: Dave1992 on December 23, 2014, 10:49:56 PM
I don't have an audio prob & don't have access to one unfortunately :/
Have you read Jacob's instructions in the tech help rules thread for creating an audio probe? It's literally a capacitor and a cable. I just use alligator clips, so I don't even have to destroy a cable.
No I haven't, can you send me a link for it?
Merry Christmas btw guys ;)
It's the tech help rules thread. It's the sticky in the tech help section. It's required reading ;) Actually, this thread should be there, I'll ask to have it moved.
Just found it, I'll build it over the weekend, keep you guys posted.
I've build the probe and checked the circuit & the noise seems to be gone. I've checked everywhere with the schematic and couldn't find anything weird.
A big thank you guys, been very helpful! :)
hello guys ! I made two pieces of the mudbunny the green russian edition.I used the 5088 transistors.The only difference is that i used 330 ohm resistors in place of the 390 ohm.My sound is more a distortion with a bit fuzz.i compared it with mudbunnies at youtube and i can hear more fuzz at them.My hfe of the trans is about 350.I used my probe and i checked that the first boost stage gives me the same signal as the input.no boost at all.Any ideas ?
Soldering maybe? Can we get pictures and voltages and things of that nature.
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