Skeptical Buffer Build Instructions Discrepencies - Problems Resolved!

[BQFS]

Hi -

I am a brand new pedal builder. I received a whole bunch of PedalPCB boards from a guy who gave up and now I am working my way through them, ordering parts I don't stock.

I am a retired electronics technician, and am not new to troubleshooting or building out circuit boards, but this one has me puzzled.

If I am not posting this correctly, I hope someone will move this to where it may better belong.

The first thing I did was to print out the build instructions. The only one (so far, and I have looked through about a dozen build instructions) that I am having difficulty with is the Skeptical Buffer. First, R13 is 10R, not 100K like a previous poster figured out.

But the layout of my board isn't the same as either of the two shown in the build instructions.

Starting from the top of the board and working downwards, on the "row" with the three switches,on my board there is room for two rectangular caps in between the switches. On the instructions, it shows four caps, two box caps on the outside of the left and right switch, and two circular caps between the switches.

On the left side of the board, there are three circular caps, C6, C3, and C105. On my board, only two caps, 10uf and 1uf.

Under the printing of Rev 2, there's a row of four caps. On my board, only three caps.

Under that "row" on my board there is one circular cap to the left of the two diodes and one to the right of the two diodes on the right. On the first page pictorial, there are two box caps to the right of the right-most diodes and no cap to the left. On the page 2 pictorial, there are no caps on either side of the two sets of diodes.

That appears to be it. I would certainly appreciate a pictorial that is correct for the board I have. Failing that, if someone could just tell me which caps go where, I would be very appreciative.

Thanks in advance for anyone's assistance. I will be glad to post a pic of the board if that will help.

Bud

 

[Robert]

You have the previous version of the PCB, follow the printing on your physical PCB for component placement.

The wiring diagram is the same as the current doc.

Ensure that the drill template lines up, there was an initial release of the PCB where the toggle switches were closer together than the current version.

 

[Nostradoomus]

The board has gone thru a few revisions. Just go by the values printed on the board and you should be fine.

 

[BQFS]

Thank you for your reassurance.

 

[BQFS]

I did get the board done, after making sure to put the switches on the wrong side first. I desoldered them and moved them to the correct side.

Then I grabbed the wrong template and drilled the holes too close together, so I widened them and covered the excess with huge washers. Looks really spectacular (pardon my sarcasm).

For the finishing touch, it turned out the 3PDT board was defective. The trace was open between the SW hole and the top middle switch lug. Wow. I don't think I will be buying any more of those. I ended up soldering the SW wire directly to the top middle lug, and the board now works fine.

I play bass, and now wish I had wired the switches out of circuit. If there's a difference, I sure don't hear it. Oh well.

 

[Feral Feline]

I did get the board done, after making sure to put the switches on the wrong side first. I desoldered them and moved them to the correct side.

Then I grabbed the wrong template and drilled the holes too close together, so I widened them and covered the excess with huge washers. Looks really spectacular (pardon my sarcasm).

For the finishing touch, it turned out the 3PDT board was defective. The trace was open between the SW hole and the top middle switch lug. Wow. I don't think I will be buying any more of those. I ended up soldering the SW wire directly to the top middle lug, and the board now works fine.

I play bass, and now wish I had wired the switches out of circuit. If there's a difference, I sure don't hear it. Oh well.

BOLD emphasis mine. ➚

As I mentioned in your other thread, it's not impossible to have a defective board, but after seeing your post here (bolded text above) I've gotta say I doubt the 3PDT-board is defective — because...

The "SW" on the daughterboard connects/is-hardwired to the centre-lug (lug #5);
the switch itself makes the final connection to lug-4, lighting up the LED when you turn the effect on and close the circuit.







You can use your DDM's continuity-setting to test this on your boards.

PedalPCB's boards are based on a coherent system — most, but not all, projects are within specific guidelines to make building easier, from one circuit to the next. Very consistent. One drill-template can work for dozens upon dozens of different builds, for example (mentioned because you had trouble with the template for this build, revised version vs old board).


I'll be looking for your road-test report in your other thread.

 

[BQFS]

BOLD emphasis mine. ➚

As I mentioned in your other thread, it's not impossible to have a defective board, but after seeing your post here (bolded text above) I've gotta say I doubt the 3PDT-board is defective — because...

The "SW" on the daughterboard connects/is-hardwired to the centre-lug (lug #5);
the switch itself makes the final connection to lug-4, lighting up the LED when you turn the effect on and close the circuit.

View attachment 89827

View attachment 89828



You can use your DDM's continuity-setting to test this on your boards.

PedalPCB's boards are based on a coherent system — most, but not all, projects are within specific guidelines to make building easier, from one circuit to the next. Very consistent. One drill-template can work for dozens upon dozens of different builds, for example (mentioned because you had trouble with the template for this build, revised version vs old board).


I'll be looking for your road-test report in your other thread.

Keep in mind, although I am not an expert on every facet of electronics, I do have two degrees in Electronics Engineering Technology with a B.S. from Cal Poly. Over and above that, I have over 50 years hands-on bench tech experience running my own electronics repair business, initially working on TVs and stereos as well as all sorts of amplification, and later repairing and upgrading bass guitars.

Although I am new to pedal building, I am far from new to every aspect of consumer electronics with emphasis on repair.

I appreciate the information you have furnished, but none of this is new to me.

I reiterate - the board is quite certainly defective. The 3DPDT switch works perfectly.

When I measure continuity between the hole on the daughter board labeled SW and the top middle switch lug, there is NO continuity at all.
When I moved the wire from the hole to the lug, the circuit worked fine, and the LED functioned as it should.

I will post up in the other thread, but the switches do indeed work. There is some difference in tone, just not very pronounced. I stand by my previous statement. The unit works great as a buffer, but the switches, as far as I am concerned, could have been left off.

 

[Feral Feline]

Okay okay!


I've got none of that experience, nor credentials. I'm just a novice DIYer trying to help out a fellow pedal-builder/bass-player.
No wonder you were confident in removing the switches and re-installing them.
I'm still a little leery of that, as I've pulled traces in the past trying to do so.

Also, hard to keep track of everything as I've been bouncing back and forth between the two threads; I posted there before seeing your post above.

I'm currently working on a compressor, my Skeptical buffer will have to wait.
What's your next build?

 

[BQFS]

Okay okay!


I've got none of that experience, nor credentials. I'm just a novice DIYer trying to help out a fellow pedal-builder/bass-player.
No wonder you were confident in removing the switches and re-installing them.
I'm still a little leery of that, as I've pulled traces in the past trying to do so.

Also, hard to keep track of everything as I've been bouncing back and forth between the two threads; I posted there before seeing your post above.

I'm currently working on a compressor, my Skeptical buffer will have to wait.
What's your next build?

My next build is a little closer to home. For the past couple of years, I've been fabricating and selling clones of the original MusicMan Stingray bass preamp. I was lucky to find a legit modern source (NJM) who produce an exact replica of the original LM4250 op amp which is crucial to the sound of the preamp. I am on my third revision. I started out using a circuit board designed by someone else, but it had some major drawbacks.

Working with a Talkbass buddy of mine, the board was redesigned. Then I got the idea to use surface mount components, for an even smaller board, and at the same time made it easier for my customers by using screw-end connector blocks instead of soldering the leads directly to the board. I made further changes by using tantalum caps in the signal path as the original used regular electrolytics.

I have sold over three dozen of those, no failures in the one year parts and labor warranty I offer.

So just today I fabricated nine more. I carelessly ran out of the end connectors and they are now taking almost two weeks to ship, so I am feeling like a moron. I probably lost some sales momentum, but I will get it back. That error won't happen again.

Working with my buddy, I came up with a pedal design. The three pots are mounted right on the pcb, and it runs on 9V battery or external source with the jack that cuts off the battery when the external source is plugged in. I am installing them in purple enclosures, and already have graphics for them.

Going to do an initial run of six, to see if there is any demand.

The big problem is trying to figure out what to sell them for. I'll be figuring that out at the same time I am building the six units.

I've been selling the onboard preamp for $99 + free shipping. I have two major competitors, both of whom have been at it way longer than me, but I think by offering a better product, more complete (they don't offer controls or a jack) and a much better warranty, I am doing okay.

My goal was one sale every other week, and until I stupidly ran out of supply, I was selling almost two a week.

I never did this to make money, and so I never figured out how much I make on each one. I would have a problem selling it for more than I am because I didn't design the circuit, and I'm not sure it's cool to make as much money as possible off someone else's effort. When I figure the pedal's selling price, I will probably figure out my cost on for the onboard one too, and then just find some reasonable markup. My guess is that it wil go for around $149 but that's just a sheer guess.

I had Tayda do the boxes which weren't near as expensive as I thought they'd be. A sticker company does my graphics, and my buddy made me a drilling template. So, it won't take too much longer, labor wise, to make a pedal compared with the onboard one.

The onboard one is fairly time consuming, because I have to cut and twist all the wires for the jack and controls and then solder the jacks and controls. Much faster now that I don't have to solder the wires to the board either.

Due to the screw terminals, it's now possible for the end user to do a solderless install, which I am sure helps sales too.

Hope I didn't bore you to death....

Bud

 

[LukeFRC]

Working with a Talkbass buddy of mine, the board was redesigned. Then I got the idea to use surface mount components, for an even smaller board, and at the same time made it easier for my customers by using screw-end connector blocks instead of soldering the leads directly to the board. I made further changes by using tantalum caps in the signal path as the original used regular electrolytics.

Random slightly OT post, but The earliest pre EB stingray preamps did use tantalum caps rather than electrolytic.

 

[BQFS]

Random slightly OT post, but The earliest pre EB stingray preamps did use tantalum caps rather than electrolytic.

You know, I did think that was true, re the tantalum caps, so thanks for reinforcing that. But I think there were subsequent versions that used all electrolytics. With a circuit that old and so many different schematics floating around the Internet, it's difficult to sort out fact from fiction. Regardless of OT or not, I will continue to use tantalums in the signal path.