I have tried to build two of these now and both don't work. Tried the rams head then the Mayo. I am building both directly from the website values. The only thing I think is that the 500pf caps and the 10n cap are very small so I don't know if I got the wrong type. Do they look right for the mayo pics? I have also read that using the BC550 transistors I might have to have them the other direction ?
This is my first builds so Im sure I did more things wrong. The first one is the rams head before I added the last resistors
(http://i.imgur.com/2UguMgp.jpg)
(http://i.imgur.com/q9348v2.jpg)
(http://i.imgur.com/rRWN3p8.jpg)
(http://i.imgur.com/Ir7NOGa.jpg)
Yup, the pinout for the BC550 is reversed from that of the 5088, for which the board was designed...... Socketing the transistors is always a good idea, allows you to experiment and correct mistakes like these...... ;) If you like, I can send you the datasheets for both?
Paul
I changed them around and now I get the hum on the Mayo like I did on the Rams head. I found out this was due to the ground on my 1/4" jacks. Now I am back to no sound. for testing I just set up input and output to the tips and the ground connecting them both at the sleeve, im sure that's right. I am going to build this audio tester tonight and give that a go.
Where is your 9v ground connected to?
The ground beside the 9v. I have it hooked up to a DC jack and have the middle pin as ground and the sleeve as the 9v.
(http://i.imgur.com/BlFJbJG.jpg)
(http://i.imgur.com/Qq2gjuR.jpg)
make sure your not grounding something on one of the pot cases. put some thin cardboard (like from a cereal box) between the board and the pots to eliminate that being an issue .
Do you have an audio probe to use? That'd be the first tool I'd use in trying to work this out. At minimum, you need a 1/4" jack (which you have) and some wire, though you may want to use a 10-100nF cap as well.
Secondly, what are you voltages?
Have you seen this thread yet? It's very helpful in giving tips for troubleshooting. http://www.madbeanpedals.com/forum/index.php?topic=902.0 (http://www.madbeanpedals.com/forum/index.php?topic=902.0)
Jacob
I will have to do the audio probe later but here are the voltages. I had to use 20k for E and 200K for the others. Please let me know if I measured wrong. I had the pedal plugged in to a 9v and used the ground from the DC jack.
Q1
E = .09 (20k)
B = 86.5 (200K)
C = 72.2 (200K)
Q2
E = .09 (20K)
B = 81.7 (200k)
C = 78.6 (200K)
Q3
E = .09 (20K)
B = 82.8 (200k)
C = 75.5 (200k)
Q4
E = 2.63 (20K)
B = 82.8 (200K)
C = 79.6 (200K)
Quote from: wretched on October 19, 2013, 03:47:21 PM
I changed them around and now I get the hum on the Mayo like I did on the Rams head. I found out this was due to the ground on my 1/4" jacks. Now I am back to no sound. for testing I just set up input and output to the tips and the ground connecting them both at the sleeve, im sure that's right. I am going to build this audio tester tonight and give that a go.
When you changed the around, did you put new ones in, or did you put the old ones back in.
If not. One or more could be damaged from the heat.
If suggest, getting them out and putting down sockets in.
George
It's a bit hard to tell from the picture, but are you sure that DC jack is wired correctly, positive lead on correct lug?
I put the same ones back in, I have to wait for the sockets to come in.
The 9v positive is on the sleeve of the DC jack.
Hey, from your measurements, I can't really tell how or what you are measuring. It sure ain't voltages, because 86.5V from a 9V supply would be pretty awesome! Looks more like resistance, and the values are different from what you wrote behind them in brackets because you measured them in circuit, which means they are in series and/or parallel with other components, which will influence your readings.
Measure your voltages like this: Make sure your DMM is set to the DC Voltage setting, put the black probe to a ground point (any will do) and the red probe to the point that you want to measure. This should give you a proper reading.
I hope you didn't toast your transistors by re-soldering them, but at least your DC jack is wired ok. Are your input and output jacks wired ok? Signal to tip and ground to sleeve? I once spent an hour debugging a build where I wired the output to the sleeve, thus dumping all signal to ground........
Paul
Thanks for the reply I will try to measure again when I get home.
For my input and output I have them correct, but I will go back and check the soldering
I am still waiting for my 100nf caps to build my audio probe. I think I might just order a second set and see if they come sooner.
GREAT news. I now have a MAYO Mudbunny!!!
Turns out my DC plug has 2 negatives and 1 positive. So I got my parts to build my audio probe and then tested the voltage first. I found no power was going to the board at all. That is fixed now.
Tested fine and sounds killer, just have to box this bad boy up :) Im sooo happy with this
Bad news is that I tried the same with the Rams head build and still nothing. I am going to try and clean up the input/output and see if that helps. However did I need to change the direction on the 2n5088 like I did for the BC550?
Quote from: wretched on October 29, 2013, 02:27:03 PM
Thanks for the reply I will try to measure again when I get home.
For my input and output I have them correct, but I will go back and check the soldering
I am still waiting for my 100nf caps to build my audio probe. I think I might just order a second set and see if they come sooner.
100nF is like candy in most pedal circuits. I buy them by the hundreds. You could also use mlcc or ceramic instead of film if it is just for an audio probe.
Hi mate, glad you got 1 working. Google Beavis audio and have a look how a dc jack works, which tabs to solder to what and why, particularly, what happens when a jack is inserted in the dc socket. all the best, Matt.
I am sure you can use a different value for the probe.
Quote from: wretched on November 06, 2013, 05:50:09 AMBad news is that I tried the same with the Rams head build and still nothing. I am going to try and clean up the input/output and see if that helps. However did I need to change the direction on the 2n5088 like I did for the BC550?
When in doubt, always check the datasheet of a component. It seems daunting at first, but you soon understand where to find what you need. In case of transistors, this link is quite handy too: http://www.beavisaudio.com/techpages/Transistor-Pinouts/
The Mudbunny board was laid out for 2N5088/9 transistors, so just follow the orientation on the PCB.
Regarding the wiring of the DC jack, always keep this as a reference: http://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf You'll see that the DC jack has two tabs for the 9V, one goes to an optional battery snap (and it's disconnected when you insert a DC plug), the other goes to the board. As you noticed, you cannot use them indifferently.
edit: as hoodoo pointed, beavis has a better explanation on the DC jack: http://www.beavisaudio.com/techpages/PedalPower/
now I am having issues with the switch. I am going to take the easy way out and use a pcb for the switch.
I am still trying to get my Rams Head going. I followed the audio probe and found some issues and am looking for help.
I don't get any sound from the C14,D5, and very little from R24. Is this normal seeing it is the power ?
Then I get sound going into C13 but not out the other end that connects to the middle Volume pot, I tired to change that cap and it is the same problem. Then C15 has nothing in or out of it.
Please let me know if you can help.
Quote from: wretched on November 24, 2013, 10:45:42 PM
I am still trying to get my Rams Head going. I followed the audio probe and found some issues and am looking for help.
I don't get any sound from the C14,D5, and very little from R24. Is this normal seeing it is the power ?
Then I get sound going into C13 but not out the other end that connects to the middle Volume pot, I tired to change that cap and it is the same problem. Then C15 has nothing in or out of it.
Please let me know if you can help.
There is no audio signal in the power path so don't worry about probing C14,D5, etc
If you had sound at C13 this is good as it is the last cap in the audio signal chain. The cap connects to lug 3 of the volume pot and lug 2 is the final output. Start again with C13, then probe 0lug 3 of the vol pot, then lug 2. What ya hearing?
Still nothing. I hear the sound on the right (red dot) but nothing on the left (black)
(http://i.imgur.com/r2IS3Xkl.jpg)
Could I try to connect the C13 right to the 3rd lug on the vol pot? Like bypass the c13 all together and bridge the "red dot" to the volume?
I don't get any sound from the volume pot lugs.
Do you have pots (or pot wires) soldered in all the pins. Hard to tell but it looks like you don't have any pots hooked up. Also how are you getting power and ground to the board?
When you say you get sound at one side of C13 is it the actual effect (fuzz) you are hearing or some other noise?
sorry that was just a picture to show what was getting sound. The board is fully populated. I get a fuzz sound on the on side and then nothing on the other.
Strange, but it worked. I bypassed the one hole and just connected the c13 cap directly to the volume pot and it worked.