@mybud
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Thanks, Barry.
You’re dead right on the fuzz aspect (wink icon here) but the updated Vibe is to me the secret sauce. Light years better than the previous incarnation, if I may so, which was ok but had far fewer options. Just a rate knob IIRC.
Groovy on the dual combo idea, as JMH himself might have said.
Voltage on the middle leg of my trimmer reads 4.12VDC (more or less 1/2 supply voltage). Try to get near to that and see if the chorus comes back.
Ok, so then clearly this is an intermittent fault. Check all your IC sockets for any dodgy joints. Then do the tap test. I’m comparing your pics to my build to see if there any errors, but all looks well so far.
Ok, let’s start from the top again. When you say ‘not working,’ it’s not chorusing or no sound in bypass or engaged?
For instance, the highlighted spots there might indicate an intermittent connection. Look for similar ‘starved’ points on the board and carefully retouch them. All this falls away if the circuit’s working as expected outside the box. Then we move on to plan B…
Here we’re trying to identify if there’s a loose connection somewhere on the board. The fact that it’s intermittent (suddenly working and then not) points to this. BUT if it’s consistently working outside the box, then the problem is either the offboard wiring or something shorting against the enclosure. To clarify, does it work consistently unboxed (IOW, no loss of chorus or dry signal until you house it)?
Well, that’s progress in one sense that you got it working for a while. Unboxed but switched on, try gently tapping each component with a pencil or similar: I suspect a loose connection or a cold solder joint somewhere. Maybe start with the trimmer and work from there.
This troubleshooting exercise is very good for learning how to fault find: I’ve had to do this more times than I care to admit 🙂 If it works unboxed and ceases when you box it, you may be inadvertently shorting something in the boxing process but let’s get the unhoused version up and running first.
Keep at it. Your perseverance will reward you with a great-sounding pedal in the long run.
Worth bearing in mind that there’s a fairly narrow spot in which the trimmer functions. I suggest playing through the engaged pedal and adjusting the trimmer in really small increments. It seems that the 4558 is functioning since you’re getting sound with it. If this doesn’t work, double-check your component values are correct and reflow any cold joints you may come across. Finally, an audio probe (there’s info on it on the site) helps to isolate any missteps and narrow down problem areas. We’ll get to the bottom of this in time.
Here are my voltages as promised. Seems to me the big discrepancy is the 4558, where you’re getting positive readings on the right hand side of the chip and I’m around 0 as you see. Try maybe first checking for any shorts at or near that socket, then replace the chip if possible.
What worries me is the different readings when you first measured from jack ground to the later ones measured from ground on the DC jack.
I’m not sure whether or not the audio ground and the power ground are on separate planes. Correction, Billy confirms this above.
This may mean that my 358 voltages are wrong since I measured everything from audio ground. Unfortunately I don’t have a simple way of accessing separate grounds the way I’ve built mine.
Have you tried adjusting the trimmer now that you’re getting the correct voltage from the power supply? Wish I could be of more use…
The two flipped ICs may (or may not) have been damaged, as Billy says. If none of the pins are showing continuity (indicating a short), that’s a plausible reason for the 358 overheating.
