Here is a request/offering for the site. As a new hobbyist, I wanted to contribute something to the community, so I took a stab at tracing my Tone Reaper. As you can tell from the pics, I obviously don’t know the proper way to go about drawing a schematic. However, it DID work on a breadboard with substitute NPN Si transistors and a couple incorrect resistor values. So it's a good launch point, I think. I hope you'll get the jist of it even without all the proper symbols/notation.
That said – I need some help identifying values. The resistors are mostly tiny 5-band metal film ones, and I can’t be sure that I’m interpreting them correctly with my inexperienced eye (might be backwards?). So there’s also a photo of the guts, and I wrote down the actual color bands. Lastly, there’s a diode marked “mystery” because the code isn’t visible in its current position on the board, and I’d rather not desolder it with my beginner skills. If anyone else has a Tone Reaper and can see the code on theirs, please share!
great job on the trace, figuring the values, and posting what it is.
resistors look good to me, and i've uploaded the layout to the main page. the one thing that i'm not sure of is the 101 and 471 caps, which would be 100pF and 470pF respectively being poly. i think they may be silver mica caps, since i haven't seen poly caps below 1nF. given that MLCC or plane old ceramics would be fine.
also, just one note, nothing wrong or bad, but the schematic is all over the place so it's not the easiest thing to follow. when you make them, especially when tracing it helps to try and keep it organized and have it flow from input to output, and have a single row for power. it not only makes it easier when trying to make a layout, but it also helps you when tracing to make sure you've got it all right, and what even more important is that you can better understand whats happening.
Awesome! You're quick. Thanks for giving everything an experienced look-over.
I barely know how to read a schematic at this point, so I just took my best shot at imitating one when tracing, and that's how it came out. (Luckily it worked when testing.) Do you happen to know if there's any sort of guide to tracing circuits or schematic writing for the average joe? While this was the only pedal I own that wasn't already on this site, I'd be happy to try more traces in the future if I get some worthy pedals, and also learn the right way to go about it. Any links would be appreciated.
honestly i'm sure there are some out there, but i don't know of them. there may be some stuff posted in the library. what i did was i used existing schematics and tried to follow it along when looking at the trace of the PCB on a pedal. tbh, i kinda jumped right in by looking at the big muff, since there are so may schematics and explanation of what's going on at each part of the circuit. just google some circuit schematic, and you'll see how they're laid out. if i can help anymore just ask and i'll try my best to help.
it's hard to trace an effect without having either good pictures top and bottom, and sometimes parts have to be removed to see where certain traces go.
Absolutely. Here are some pics to help answer that as best I can. They are:
1) Two legible shots of the printed capacitor values
2) Side by side from the soldering side of the PCB, with my tracing drawn over the top as I interpreted it
3) Side by side from the mounting side of the PCB, with tracing over the top again
Lastly, my interpretation of the tone sweep on the real pedal is that it isn't especially pronounced. Some of the youtube videos that are less produced make that easier to hear. So despite these values being strange, I'm not sure that they're "wrong." When I was swapping in 4.7nf for instance (in for 470pf), the sweep was then quite a bit more pronounced than the real pedal. But that's strictly my ears telling me that, so take it with a grain of salt.
If I can help with anything else, just tell me what you need and I'll do my best.
Yip...that settles it. You were spot on! BMP tone control with less than ideal cap values (compared to tradition). Excellent job on the trace Dan.
Only thing puzzling me is why the 470pF cap is much bigger (physically) than the 10nF. My experience has always been, the bigger the value, the bigger the size. Don'y suppose you have a meter that measures capacitance? You could test both caps without removing them. The results won't be vary accurate but should be close enough to guess.
I've seen boards with that cap being mlcc and some with it being silver mica. This board still confuses me we to the value of some caps because they all appear to be Mylar and I've never seen a Mylar in pF like that.
Unfortunately I only have a cheap multimeter, no capacitance meter. I'm too new to this hobby to justify buying new equipment, but I'll have a look at some of the gear pages of the forum and consider picking up a cheap one to solve this mystery.