MudBunny issues

[wretched]

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

[DutchMF]

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

[wretched]

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.

[pryde]

Where is your 9v ground connected to?

[wretched]

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.

[angrykoko]

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 .

[jkokura]

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

Jacob

[wretched]

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)

[hammerheadmusicman]

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

[hoodoo]

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?

[wretched]

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.

[DutchMF]

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

[wretched]

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.

[wretched]

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?

[rullywowr]

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.