gtfields13
Well-known member
(or, How many mistakes can you make at one time.)
Not quite to the headache, but I definitely had one of those days where the universe is telling you to just stop doing and call it a day.
Last week I received my first full self-designed PCB - nothing fancy, just a PNP/NPN side by side Fuzz Face (ala Twin Face) with additional trim pots to allow for adjustments in the case. I built up one of the boards over the weekend, but clearly something was wrong with my design - levels are too low and fuzz was barely getting started.
After, well, living the rest of life (life beyond music electronics?) I started on another PCB, but building up the NPN side with jumpers to bypass most of the added trimpots. Simplest thing I've built in months - maybe 20 components total. And when I plugged into the Auditorium, no-joy, no nothin'. The upside to the simplicity is that there isn't a whole lot to look for, and I also had a Huntington Audio Fuzz Explorer with identical layout to do side by side comparisons.
I should have stopped when I was just not getting solder to flow right. I don't really know what the difference is, but some days the tinning on my iron must be perfect because I just touch-solder and perfect joints in like 1 second. Other days, nothing is flowing into the joint. Today was the latter kind of day.
The list of fail:
1. grabbed a wrong resistor. glaringly obvious when you're looking for 47K and there is no yellow to be found. Must have reached into the next-over bin in my frequent use box.
2. trickier - also installed a 1K trimpot where 10k was intended. That well definitely mess with the Q2 collector bias on a Fuzz Face. Destroyed the 1K removing from the PCB. 'cause, why not damage the expensive parts..
3. Finally confirmed that all the parts were right, but I could not see any changes to Q2 bias, no matter what I did with the bias pot. But was I really measuring Q2? No. In my cleverness to make a swiss-army-knife of a PCB, I have put in a row of header pins to make bias adjustments / tuning super easy. And at some point I touched the actual transistor and got a very different number. Huh. Turns out that the coup-de-grace of my evening work was a completely floating (unsoldered) lead on the transistor. This is what I get for leaving my contact lenses in and working with reading glasses where I really can't focus on anything up close. Usually when I am doing a significant amount of work, I ditch the contacts or glasses, and my natural nearsightedness is perfect for solder work. It's just not perfect for after I am done when I want to look at a screen (and I am hating progressives for computer work now).
Yep. So I fixed all my goofs and this side of the PCB works just as it should. Now I am going to add in the trimpots one-at-a-time and figure out what is causing the volume problem. I think I know, but I am going to trouble shoot this from the basic circuit up.
So after this, no more solder or pedals for the day.
Not quite to the headache, but I definitely had one of those days where the universe is telling you to just stop doing and call it a day.
Last week I received my first full self-designed PCB - nothing fancy, just a PNP/NPN side by side Fuzz Face (ala Twin Face) with additional trim pots to allow for adjustments in the case. I built up one of the boards over the weekend, but clearly something was wrong with my design - levels are too low and fuzz was barely getting started.
After, well, living the rest of life (life beyond music electronics?) I started on another PCB, but building up the NPN side with jumpers to bypass most of the added trimpots. Simplest thing I've built in months - maybe 20 components total. And when I plugged into the Auditorium, no-joy, no nothin'. The upside to the simplicity is that there isn't a whole lot to look for, and I also had a Huntington Audio Fuzz Explorer with identical layout to do side by side comparisons.
I should have stopped when I was just not getting solder to flow right. I don't really know what the difference is, but some days the tinning on my iron must be perfect because I just touch-solder and perfect joints in like 1 second. Other days, nothing is flowing into the joint. Today was the latter kind of day.
The list of fail:
1. grabbed a wrong resistor. glaringly obvious when you're looking for 47K and there is no yellow to be found. Must have reached into the next-over bin in my frequent use box.
2. trickier - also installed a 1K trimpot where 10k was intended. That well definitely mess with the Q2 collector bias on a Fuzz Face. Destroyed the 1K removing from the PCB. 'cause, why not damage the expensive parts..
3. Finally confirmed that all the parts were right, but I could not see any changes to Q2 bias, no matter what I did with the bias pot. But was I really measuring Q2? No. In my cleverness to make a swiss-army-knife of a PCB, I have put in a row of header pins to make bias adjustments / tuning super easy. And at some point I touched the actual transistor and got a very different number. Huh. Turns out that the coup-de-grace of my evening work was a completely floating (unsoldered) lead on the transistor. This is what I get for leaving my contact lenses in and working with reading glasses where I really can't focus on anything up close. Usually when I am doing a significant amount of work, I ditch the contacts or glasses, and my natural nearsightedness is perfect for solder work. It's just not perfect for after I am done when I want to look at a screen (and I am hating progressives for computer work now).
Yep. So I fixed all my goofs and this side of the PCB works just as it should. Now I am going to add in the trimpots one-at-a-time and figure out what is causing the volume problem. I think I know, but I am going to trouble shoot this from the basic circuit up.
So after this, no more solder or pedals for the day.
