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Hello! I’m Elio, and it’s the first time I’ve started building a guitar pedal, but not the first time I’ve used a soldering iron, so I went quite quickly in populating the PCB and soldering the components. What’s new for me is the mass of cables and the 3PDT board with its switch. The bypass signal, the LED and the power supply work correctly, but once the main switch is activated the signal stops passing and in its place I find a high frequency whistle. I would like to point out that in some combinations of selectors and potentiometers the whistle is not present, but the signal does not pass anyway; furthermore, by physically touching the base of the gain potentiometer the whistling disappears, the right LED (D4) lights up, but still no signal. When the whistle is present, the potentiometers and switches have some effect on its frequency and intensity.
The input voltage is 8.92V, the 3DPT board is 8.97V, the pcb in 0.4 mV, pcb out does not measure (my mistake?), chip 8.6 V, transistor 4.36 V, electrolytic capacitor 8.77 V, 9v pcb left 8.98 V, 9v pcb right 8.94 V. I quickly checked the rest of the accessible components (they are partly covered by the potentiometers) and everything seems ok, let me know if other measurements are needed.
I checked the continuity of all cables and components and there is nothing strange. Strange things I’ve done are: solder R12 onto the PCB, then re-solder it onto the 3PDT; cut and connect a potentiometer with cables (to make it fit in the pre-cut chassis); I might have soldered the cables of the two smaller switches backwards.
Sorry for the general uglyness of everything, I hope it’s not detrimental for help 🙂Hey Elio. Welcome to the forum. Your pictures did not post. Most likely you have a ground problem or something touching something else that it shouldn’t touch. Don’t forget that bad pots do exist and can take a while to find. You can bypass the switches to see if the circuit works. When you repost pictures they will need to show a real clear front and back and all of the off board wiring. A mess of wires is hard to see though but several angles of pictures could help. Triple check all of your components against a color code chart where applicable. If you are using sockets make sure there are no bent pins under the IC. Let us know what you find out.
Hi again, here you can find the photos, I thought that by right-clicking the image icon and selecting “open image on another tab” it could work, sorry.
https://drive.google.com/drive/folders/18imHt0uUqGt62gPVME-H3MbhBiQdxi3EExcellent photos Elio. So there is a nice trick I think I learned it from Wilkie1. It takes more time but it’s worth it if you have no pressing deadlines. For the off-board wiring touch each stripped wire end onto the soldering iron and let the jacket melt back a little and then cool before you insert it into the solder pad of the board. This makes the jacket at the end of the wire now to be tough against further melting. The end result is to have the jacket of each wire butt right upto the board so that nothing bad can ever happen in that spot. And it will look awesome. Also switch to pre-tinned wire like Barry’s in the shop. It makes life much easier. I’m going to copy and paste what I suggested for another fellow builder just yesterday. ” I solder at about 650-700 degrees and use a pointy tip which is great for Barry’s boards. And I swear, after a bunch of years, I still count seconds to be sure I gave enough heat for a good melt but don’t overdo it. Thousand one thousand two… It’s important enough that I do it all the time. For example no more than 4 seconds on a mini switch tab or you will start to melt it. A full 6-8 seconds for a pot tab. Try to go too fast and you can get a cold joint which will allow the wire to pull right out. But for the boards be aware that the ground connections and many others connect to a plane of copper in the middle of the board instead of traces, the ground plane. I notice that these solder pads can take an extra second or two because you are heating a large area around the pad. They are visible with their crisscross design. If the solder looks weird it is weird and worth a second look.”
I say all that to give you the bad news that you probably have to reflow all of the solder joints and let the solder flow for sure before you pull the iron away. Let the heat do it’s job. There is too much solder in many spots and a good solder sucker is advised. As they say, the solder joint should look like a hershey’s kiss. Watch a couple short videos for technique and check out the combo build guide for some finished photos of what I’m taking about. You’ll need to get good at flowing the solder. I use solder with lead in it. And to get good at snipping off the ends closely and neatly. That should solve the problems. Another good hint is to have quality toothpicks on hand to help clean out stubborn solder. Sorry dude. Let us know what happens. Cheers
Ok it went perfectly, I had already seen another topic in which was suggested to reflow ecc. ecc. so I did and it worked. I’ve removed the excessive solder and made better connection for the cables, probably the pcb out part was the problem. Now it really sounds great! I’m so happy
Hey just one last thing: I realized that there isn’t space for a battery inside the chassis so I unsoldered the battery clip and tried the circuit with power supply, and it didn’t work. I tried resoldering the cable link on the socket but it did nothing, and by measuring the voltage I found out the polarity on the socket is reversed (???): so should I reverse the cables (which, I think, is really a bad idea) or did I take the wrong 9V power supply?
EDIT: definitely it’s the power supply, someone else linked this holy grail of a site
I will try the correct one in a few days
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