Hi everybody,
I'll preface this post by saying this is my fourth build, but it's my first "non-kit" build that I've attempted. I got the Mangler, I used matched PNP-Ge transistors from Smallbear (and used the Smallbear-supplied resistors instead of the resistor values on the Madbean schematic).
After I assembled the board and went to test it, all I got was a loud buzz. It didn't matter if bypass was on or not. I checked the other elements of my rig (guitar/amp/cable) to make sure they were okay, and they were.
So, based on what I've read on other posts, this means that there's a grounding issue with the Mangler, right? So, I went back and reflowed all my connections and gave it another shot. I also made sure that the pots weren't touching the board. They weren't. I fired it up again and got the same result.
I've included pics - any assistance and insight are much appreciated. Thanks.
(http://img841.imageshack.us/img841/9610/img8401n.th.jpg) (http://imageshack.us/photo/my-images/841/img8401n.jpg/)
(http://img837.imageshack.us/img837/6634/img2136v.th.jpg) (http://imageshack.us/photo/my-images/837/img2136v.jpg/)
(http://img545.imageshack.us/img545/8481/img7793h.th.jpg) (http://imageshack.us/photo/my-images/545/img7793h.jpg/)
I see that you have the sleeve of the input jack grounded. Did you also ground the sleeve of the output jack? This is necessary when testing outside of an enclosure. It is not necessary to ground both sleeves once in an enclosure, provided you are using those metal frame jacks. This is because the enclosure itself grounds the sleeve of the output jack.
Yeah it looks like you may not have a ground wire connected. Also check the orientation of that 2.2uF electrolytic cap. I am not 100% sure because I haven't seen a cap quite like that but it looks like it might be in backwards from the picture.
Yep, run a wire with alligator clips from the input jack ground to the output jack ground and see if that fixes it. Just needs to be temporary because the enclosure will ground the output when it's all put together.
I'd suggest building one of these if you are going to continue building pedals. No need to hook up a 3pdt and jacks to see if your circuit is working right. I use mine all the time and it's great!
http://www.madbeanpedals.com/forum/index.php?topic=1140.0
Are you getting any signal when the effect is activated or just the buzz?
Quote from: JakeFuzz on August 02, 2012, 02:52:50 PM
Yeah it looks like you may not have a ground wire connected. Also check the orientation of that 2.2uF electrolytic cap. I am not 100% sure because I haven't seen a cap quite like that but it looks like it might be in backwards from the picture.
I beleive those are non polar elctros he's using
Just got home from work. Thanks for all the replies!
Murdog, I'll try your idea first and see if that fixes the buzz.
Quote from: jimijam on August 02, 2012, 03:28:57 PM
Quote from: JakeFuzz on August 02, 2012, 02:52:50 PM
Yeah it looks like you may not have a ground wire connected. Also check the orientation of that 2.2uF electrolytic cap. I am not 100% sure because I haven't seen a cap quite like that but it looks like it might be in backwards from the picture.
I beleive those are non polar elctros he's using
I think I have the right caps (I think) b/c they had the "-" markings running down the side. However, the 2.2uF cap had a "+" marking instead of a "-" so I flipped it around. Just to confirm, since this is a positive ground effect the negative side of an electrolytic cap runs into the square pad on the circuit, right?
UPDATE: All I needed to do was run a cable from both jacks and that solved the problem. Electrolytic caps were in the right position. Thanks for all the help everybody.
Okay, I got the Mangler working....sort of. I tested it before I boxed it up and it sounded good and worked fine. But now that I have it boxed, I'm having trouble with the transistor in Q1.
I can get the effect to work, and when I switch to bypass, the signal is fine. But when I try to turn the effect back on, I get no signal until I fidget with the transistor. So far, the only thing I've done to troubleshoot is reflow the soldering joints on the socket.
It seems like 1) the transistor isn't fitting in the socket very well or 2) something keeps shorting out the circuit. I made a quick video and posted the link below. Any ideas?
I hate using sockets for precisely this reason, and I've pretty much given up on them for silicon transistors (unless I wanna try different varieties). With Germaniums they're still a good idea. One technique I've used is to put just enough foam on the inside of the enclosure lid to hold the transistor down firmly when it is closed. Just make sure you're not crushing it and making the leads buckle.
Someone also suggested using poster putty to hold transistor leads into sockets. I've never tried it, but it's worth a shot.
If you can identify the troublesome lead/socket, you could always just solder that one lead in place. Desoldering a single lead is rarely troublesome if you wanted to reuse the transistors elsewhere. Just always use copper alligator clips as heat sinks and be as fast as possible. If you need to remove it, I wouldn't even use real desoldering techniques -- I would just heat the joint and pull the transistor out with pliers simultaneously. (You can remove the old solder later once the transistor is out of harm's way.) Easy if you only solder one lead, a pain in the ass if you've soldered all three. Good luck!
I have had good luck crimping the ends of the leads flat then stick em in the socket. Also the foam padding is a good idea in addition.
Despite crimping the leads on the transistors and put some padding in the back of the enclosure, the problem isn't solved.
I think there might be some sort of grounding issue or that I made some huge mistake somewhere. What I noticed is that I can get the effect to work by jiggling Q1, but if I touch the enclosure (or any other part of the guts for that matter) with a screwdriver, the effect instantly cuts off. If I jiggle Q1, it comes back on. If I try to screw on the backplate of the enclosure, the effect cuts out as soon as I touch the screwdriver to the metal of said enclosure. What gives?
I know you said in your original post that you were sure the pots weren't touching the back of the board, but that was before you boxed it. Did you put anything between them in the meantime? I like to use 3M mounting tape, but anything non-conductive will work.
I used sockets on my Current Lover for the transistors and the timing capacitor. I wound up wishing I never did.
Soldered the little buggers into the sockets. Let's see 'em fall out now!
I looks like the fuzz-pot might be touching the enclosure with one of its legs in the top left corner (?) I accidetly had that problem with a cosmopolitan I made a while back ago. I just put some paper between it and the box.
might be worth to have a quick look at.
Yep, it's probably the pot backs grounding out something on the board.
I sometimes use double-sided mounting tape on the backs of the pots. It insulates and also holds the board steady.
Hey everybody, thanks for the help - the Mangler is now "mangling" as it should!
I soldered the wobbly leg of the transistor into the socket. I put padding in the back of the enclosure, placed a small strip of poster board between the pots and the board, and put two strips of poster board in the upper corners of the enclosure to keep the pots from touching the enclosure. I'm not sure where the original problem was, but all of these changes resulted in perfect operation! I'll be sure to post a pic of the completed build when I get a chance later today.
Cool! Glad you got it working.
good to hear!