[Billy]

I’m taking it you took this photo with the IC in the wrong way? The dot should go towards the centre of the pcb

Make sure your stereo jack is wired correctly can’t see it clearly but it’s easy to mix up the tip and ring connections, normally your stereo jack would be used on the input side although as far as I know it doesn’t matter put a jack into it and follow the connections around to their solder lugs like this

You can also use your meters continuity check to make sure you have it wired correctly it sounds like you may have the tip and ring mixed up

If your stereo jack is wired correctly post your voltage readings to the ground and 9v pads, for the IC pins and a clear photo of the DC jack

 

 

 

 

[Billy]

No you’re correct 471 is 470pf

That’s nearly 10 times bigger it will work but not as intended

I’d buy a 50pf or capacitor as advised in the build doc

Or if you’ve got a closer value use that

 

[Billy]

Post some images Brooks I’ve checked and re checked faulty builds and still missed incorrect components

Have you made sure you’ve connected ground to G2

[Billy]

https://en.wikipedia.org/wiki/Low-frequency_oscillation

I’ll move your post over to build support

Doesn’t sound like your LFO is working correctly but remember the IC is out of socket

Try the same thing with the IC back in it’s socket

The LFO output voltage should change or pulse as you turn the rate pot

In general your build looks pretty good so it may well be something simple like a dry solder joint I just think it’s better to try and find what’s faulty and learn as you go along for future builds rather than just reflow solder joints

 

[Billy]

Sounds like your LFO isn’t working

Make sure the metal back of your pots aren’t touching anything on the pcb

Try taking IC1 out of it’s socket and see if you get fluctuating voltage on pins 5 and 6 you can put your black probe in pin 4 socket (ground) then red into pin 5 and 6 socket and turn the rate pot see if it changes

Set the deep pot to maximum

[Billy]

They look ok I think you’ve probably got pins 5 to 8 The wrong way round if you refer to the IC pin numbering image you go left of dot or notch is pin 1 down to 4 then 5 up to 8 in a U shape

Assuming your power in is 9.54v then that’s what it is

Take the voltage again on IC1 pin 7 hold it on the pin to see if it varies you should also get varying voltage on the rate potentiometer

Also turning the trimmer try to set the voltage on T1 G  (gate) pin to 2.2v so turn it a little check voltage on the gate until it’s around 2v if you turn it and it lowers the voltage you know you have to turn it the other way to increase voltage

We know the phasing works when you turn the trimmer so it’s just fine tuning

T1 to 4 work as variable resistors to shift the phase stages it’s just a case of trying to find out whether it’s due to them or the LFO not working correctly or something else of course

So all we’re doing is checking parts of the circuit before we do anything else

Just for your own interest if you look at the schematic it’s like join the dots you can see for example D1 the 5V1 zener connects to T1 S (source) D1 ideally puts out close to 5.1v but will usually have a voltage drop  across it typically 0.6v for a silicon diode so that tells us 4.50 is about right you’d then see what that connects to which is T1 source so you’d expect around 4.50 there too

You can see all the transistor source pins are connected so again should all be around the same voltage

That’s what we’re basically doing

Your IC voltages on the whole look ok, IC1 is the LFO (low frequency oscillator) that basically oscillates or modulates the signal so it should vary with the rate control on its inputs pins 5 and 6 and output pin 7

 

[Billy]

Yes they look to be orientated correctly and you do need to power the circuit to take voltage readings

Your voltage readings don’t look correct you’ve definitely got it on DC voltage not AC?

Are they 4.50 where you say 450 etc

You’d need to specify the pin numbers

E.g.

IC1

1.

2.

3.

4.

5.

6.

7.

8.

We’re trying to establish if your LFO is working IC1 pins 5, 6 and 7

Also take T1, 2, 3 and 4 voltages left to right pins are G (gate), S (source), D (drain) as written on the pcb list them like that e.g.

T1

G 2.2V

S 5V

D 5V

etc for all 4

[Billy]

I’ve never used the MN3207 in this circuit what I do know is internally it’s the same circuit with the main difference being one is PMOS, MN3007  the other NMOS MN3207  meaning one requires negative power 3007 the other positive

So for this circuit I’d expect voltages would be similar

List what voltages you get by pin number

The first thing I would do is check the BBD

jumpers are correct and have good solder joints I’d also compare the voltages on the empty socket and check D4 voltages

Basically check everything you can to see whether the 3207 is faulty or not

Check all the +9v and VB points on the schematic

You are correct regarding the LFO and the clock pulse coming from the 4047 so again you can see you’d expect the same voltage on pins 10 and 11 of the 4047 and pins 2 and 6 of the 3207 then as you say output from pins 7 and 8 up to IC1B where it’s mixed with the clean from R14

It could be something prior to the 3207 causing your fault so it’s just a case of checking everything from the information you have eg is the trimmer working correctly what voltage do you get Q1 base would let you know so you’ve more or less found your problem area you just need to make sure everything up to that point is good

Weirdly enough I quite enjoy debugging you learn a lot from it for future builds

I usually print the schematic and mark it off as I check everything I rarely swap components out just in case some error I’ve made blew it in the first place

But you’re definitely using the right approach now all you need to do is try and enjoy beating it when you find and fix it just keep saying you ain’t beating me mini me!

 

 

[Billy]

Sounds like it may be your transistors what type of FET transistors are you using 2N5952 or 2N5457

Check what voltage you get on both sides of your zener diode D1 simply place your meter black probe on a ground pad and touch both sides of the zener diode with the red probe with your meter set to 20 DC voltage the V with a line and dotted line under it (see below)

Also check you get a pulsing changing voltage at IC1 pin 7 pin numbers go like this again meter set for 20VDC black probe to ground red to pin 7

[Billy]

Set the speed knob to half way depth up full

Set the trimmer to just before half way and turn it in very small amounts until you hear phasing

You have to set the trimmer to get phasing it is a very small range on the trimmer so just turn it a little at a time

 

[Billy]

Did you adjust the trimmer to try to get phasing

To take voltages with your meter set it to 20 vdc place your black probe on the ground pad and red probe to the +9v pad

[Billy]

Very difficult to find the build document on the musikding site post a link to that

What voltage do you get at the +9v and gnd pads

Could you post a close up of your DC jack wiring

Do you get bypass signal

[Billy]

Just add some new solder to the joints you think are dry

What exactly is the pedal doing or not doing it may be something else causing your fault my advice is to post nice clear pictures of both sides of the pcb and wiring to footswitch DC jack and in and out jacks so that we can clearly see components and trace the wiring also post links to the build document and what the circuit is

Your solder joints look ok to me

Was the first solder you used unleaded that has a higher melting point than leaded solder and doesn’t flow as quickly

[Billy]

Anode + to R10 bottom pad, cathode stripe side to top pad

It’s a reverse polarity protection diode Robert

[Billy]

Gabe the best way to check is to put a jack into the socket and follow the solder lugs round, this is a stereo jack but the principle’s the same for mono jacks you can see where the tip, ring or sleeve (ground) connect and follow it round to it’s solder lug connection

The ground lug is always directly connected to the sleeve

Guitarpcb boards have a white square pad with a small T for tip and a ground pad right next to it

[Billy]

No problem Ron jargon free it’s easier to understand but hard to write you will often find in electronics things are the same but little is universal

You’ll see for example schematics labelling every capacitor in uf so you’ll get 0.01uf which is 10nf and also 10,000pf all the same but different units fortunately GPCB don’t do that so it’s a lot easier to recognize the capacitor type required

You’ll also get assumptions made that you know how things are done so you’ll rarely see switch wiring on schematics

Then you’ve got US and European symbols etc being different

So yes there’s definitely a lot that can throw and confuse you but that’s what we’re here for we may not answer immediately but will eventually!

 

[Billy]

A 3PDT is basically 3 SPDT switches side by side

So 3 rows across and the 3 poles vertically

So you have the middle common row connected to your audio in and out ( guitar signal) via the in and out jack tips

The middle common row is either thrown to the top row connecting your in jack tip to the circuit input and taking your guitar signal through the effects circuit and out via circuit out to the output jack and your amp at the same time grounding and lighting your LED

Thrown or clicked the other way it connects to the bottom row which switches your guitar signal still going in at the input jack but this time connecting it to lug 3 straight over to lug 9 via the jumper and out via the output jack to your amp or next effect in your chain bypassing the circuit completely and at the same time breaking the ground connection to your LED and switching it off

If you used a common anode bi colour LED then the second colour would be connected to lug 6 so you’d have the first colour say green connected to lug 4 when switched to effects mode and connected to lug 5 ground  it would light green

The second colour say red would light red when switched to bypass because the switch would be thrown connecting ground from 5 to 6 and lighting that side

If you’re using a single colour LED then lug 6 can be left empty it won’t matter it just connects lug 5 to nothing

The switch from a power and ground point of view is independent of the circuit so won’t cause an open circuit

So put simply you are making and breaking what the middle common row connects to if you look below it either connects the lugs joined by the purple lines (throw 1) effects mode or red lines (throw 2) bypass mode

Bit of a novel but hope it helps you’re just simply routing your guitar signal one way or the other where you want it to go

You will get used to it for the majority of toggle and footswitches the middle set of lugs are always common to the two outer sets of lugs

[Author]

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