October 6, 2019 at 9:22 pm #7025
Hey, so I’ve built a few pedals off sites with detailed instructions and never had a problem so maybe I overestimated my skill level. Realizing I don’t know much beyond soldering and reading a wiring diagram (maybe?) I don’t know how to read a circuit diagram and don’t really know how to take voltages. Make fun of me if you want, that’s cool, but I’m out on a limb here.
I’m building a Tone Bender as a gift for a friend and got the Pump’d Up kit off Pedals Parts and Kits. First thing is obviously the build guide is a little more basic than I’m used to but I thought i could make it work. The real kick in the pants was the build guide is for the version 2.1 PCB and I received a v3 PCB? Different layout so that was tricky, placing parts isn’t hard but when it came to wiring I’m trying to read the old diagram and apply it to the new PCB layout.
At first it didn’t work at all, bypass and LED but no sound, but I quickly learned that was due to me not knowing about the T pads on the in and out (which I found on some threads here but about the older PCB). I rewired that and now I get A sound but not a good one. It sounds like there’s fuzz but there’s almost no volume even with the pots maxes and it’s very crackly. I tried reflowing solder joints and replacing a couple wires to no avail. At this point I am at the end of my knowledge.
I guess first question is why is there a new PCB with no guide for it?
Second question would be if anyone can help me diagnose. I’m worried maybe I fried the transistors? I don’t want to order a new set from Small Bear unless I have to. Any help would be appreciated folks. Thanks!October 6, 2019 at 11:43 pm #7026
The extensive guides for beginners are on the Guides Page. Since all builds are almost exactly the same we simply do not repeat this large amount of redundant information for multiple reasons. That said it is always available to anyone and unlike other places we have a dedicated forum to help. Go to our Guides Page by using the big Red button on either the Form Home Page or the actual Home Page of GuitarPCB
See image below:
To answer the first question:
We just upgraded the design to v3 which was entirely cosmetic. I simply did not add a second board photo yet as I have been in the hospital. That said onto the build questions:
The V3 layout only has some some components moved around to make more space for the transistors to fit but no part numbers were changed. The In and Out wiring is exactly the same and all parts are populated exactly the same using the board silkscreen as your layout guide. We would have gladly clarified this before building or during building since we are here to help and do not assume we are going to berate you.
Our unique In/Out wiring scheme additionally is exactly the same for all pedals. Again beginners can find these Guides on our Guides Page for reference or even print them out since they are a “one size fits all”.
Probable Build Issues:
- I cannot tell exactly from the photos provided but you cannot lay the solder side of the board against an enclosure without some type of non-conductive protective barrier (electrical tape) or the bulging solder joints will short out against the enclosure. Likely why you would have “crackly noises” and other issues.
- You absolutely must Bias a Fuzz pedal for it to sound correct (this is a fine adjustment) so it is not really considered a beginner pedal however it is not that hard to do. You must take voltages using your DMM and testing the Collector with the Red probe and place a black probe on any ground and take a voltage reading and simply adjust the trimmer till you get the required reading. (again see our Guides Page).
Here is a copy and paste from the actual build doc:
In order to have this circuit sound like a Tone Bender, you must use transistors in the recommended gain (hFE) ranges and bias the circuit. There is a 20K trimmer potentiometer on this board designed to help you adjust the bias. Using your digital multimeter (DMM), measure the voltage between ground and the collector pin of Q3, and turn the trimmer to the right until your DMM reads around -7V. The board layout has each pin of the transistors marked if you look closely enough (zoom in or print this document). The bias can be adjusted up or down by a volt or so to your personal liking. There have been reports of some original vintage tone benders having the bias as high as -8.5V, while other germanium fuzz pedals like the fuzz face were biased at around -4.7V. In addition to a slight change to the tone, a larger negative bias value will increase the circuit’s output level, which may factor into where you decide to set the bias.
As you can see this circuit will not function without Biasing. This is the same for any PNP Germanium Fuzz project available on any site.
If you need further help after checking over the Guides on the Guides Page we will need voltage readings and just ask the basic questions of what you do not understand about biasing or whatever.
I hope that helps.October 7, 2019 at 11:55 am #7030
Thanks for the reply. I apologize if my post seemed to be slagging this site and the guides. I bought the kit off another site not quite knowing how this all worked. When I got the build guide from them I was confused why the layout was different and didn’t know there was other preliminary, general guides here I should have read first. My fault, probably, for not doing enough research.
All I can say is I know for sure the solder joints on the PCB aren’t touching the enclosure, it’s held up by the LED on the one end and I purposely ran wiring underneath, as well, as a cushion. It sits about 1/4″ or more above on all edges. Besides, the audio issue happened with the entire build out of the enclosure.
The signal coming through sounds about as loud as if someone was playing music on headphones and you’re sitting next to them on a bus. There’s very little volume at all. Not sure that’s just a bias issue? I read the build guide, before posting here, and tried taking the voltage from the Q3 collector and got I think around -9.13 and the trim pot did nothing to change the voltage. I tried adjusting the bias, by ear, with the pedal plugged in and it changed the sound quality somewhat but does nothing to change the output.
I’ve read through the guides and I think I know where to take voltages, so I’ll try and do that and post. But I think I may also be too dumb, for lack of a better word, for builds like this.
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