Internal trim pot orientation question

Danny1969

The J out wire is not connected is it ?  ... is that off intentionally for some reason ?

Fuengi

ICBM said:

Nothing I can see that's obvious - unless the spring terminal on the input jack is touching the casing?

(Just as an aside, why do these kits never give you shakeproof washers for the jacks? Or most boutique pedal makers fit them...)

I'll double check that tomorrow. 

Didn't know what shake proof washers are, will take a look. Plan is to wean myself off kits and start doing some simple breadboard layouts so I can build up a better understanding of circuits. Good to have a standard for the build process. 

Fuengi

Danny1969 said:

The J out wire is not connected is it ?  ... is that off intentionally for some reason ?

I think you can use either Jo connection for the output jack. 

Danny1969

Fuengi said:

Danny1969 said:

The J out wire is not connected is it ?  ... is that off intentionally for some reason ?

I think you can use either Jo connection for the output jack. 

Yeah I can see the track joins both but I can't see the wire joined to the track in that pic, if it is then fine

I think it's an offboard wiring  / switch problem, PCB looks fine as far as I can tell. If it was me I would connect 2 jack sockets to the in and out and test the PCB without footswitch etc

Cookiemonster

Yes test without foot switch, always. 
The jack in doesn't look connected. I would redo that.  Actually on closer look that switch is confusing for jack in and out. Double check the wiring on the site, it might be that simple

Cookiemonster

Fuengi said:

ICBM said:

Nothing I can see that's obvious - unless the spring terminal on the input jack is touching the casing?

(Just as an aside, why do these kits never give you shakeproof washers for the jacks? Or most boutique pedal makers fit them...)

I'll double check that tomorrow. 

Didn't know what shake proof washers are, will take a look. Plan is to wean myself off kits and start doing some simple breadboard layouts so I can build up a better understanding of circuits. Good to have a standard for the build process. 

Best thing I did was start using breadboards. Check out beavis audio for some breadboard layouts, I put together a fuzz face in a few minutes, also created a Bazz fuss in a Bazz fuss and other things

Fuengi

Cookiemonster said:

Fuengi said:

ICBM said:

Nothing I can see that's obvious - unless the spring terminal on the input jack is touching the casing?

(Just as an aside, why do these kits never give you shakeproof washers for the jacks? Or most boutique pedal makers fit them...)

I'll double check that tomorrow. 

Didn't know what shake proof washers are, will take a look. Plan is to wean myself off kits and start doing some simple breadboard layouts so I can build up a better understanding of circuits. Good to have a standard for the build process. 

Best thing I did was start using breadboards. Check out beavis audio for some breadboard layouts, I put together a fuzz face in a few minutes, also created a Bazz fuss in a Bazz fuss and other things

Where did you get a decent breadboard from? The ones I've seen are less than £2 which makes me dubious of the quality. 

Fuengi

ICBM said:

Nothing I can see that's obvious - unless the spring terminal on the input jack is touching the casing?

(Just as an aside, why do these kits never give you shakeproof washers for the jacks? Or most boutique pedal makers fit them...)

It's clear, no short to the casing.

On testing the continuity through the switch JI is switching between CI and G.

Cookiemonster

Fuengi said:

Cookiemonster said:

Fuengi said:

ICBM said:

Nothing I can see that's obvious - unless the spring terminal on the input jack is touching the casing?

(Just as an aside, why do these kits never give you shakeproof washers for the jacks? Or most boutique pedal makers fit them...)

I'll double check that tomorrow. 

Didn't know what shake proof washers are, will take a look. Plan is to wean myself off kits and start doing some simple breadboard layouts so I can build up a better understanding of circuits. Good to have a standard for the build process. 

Best thing I did was start using breadboards. Check out beavis audio for some breadboard layouts, I put together a fuzz face in a few minutes, also created a Bazz fuss in a Bazz fuss and other things

Where did you get a decent breadboard from? The ones I've seen are less than £2 which makes me dubious of the quality. 

Very kindly a pedal maker sent me some parts and two boards. But I've just got another from bits box. You can also buy a capacitor pack and a resistor pack on there.
If you have a look at the beavis audio breadboard layouts you can then order things you need for a fuzz face, boost, red llama etc. 

ICBM

Fuengi said:

It's clear, no short to the casing. 

On testing the continuity through the switch JI is switching between CI and G.

Do you mean CI is switching between JI and G? If so that's correct. The circuit input should be connected to the jack when the pedal is on and to ground (to mute noise) when it's bypassed.

If JI is actually switching to G then there's something very wrong with the switch wiring! Unless it's switching to JO (correctly for bypass) and the output jack is shorted instead.

Fuengi

Danny1969 said:

Fuengi said:

Danny1969 said:

The J out wire is not connected is it ?  ... is that off intentionally for some reason ?

I think you can use either Jo connection for the output jack. 

Yeah I can see the track joins both but I can't see the wire joined to the track in that pic, if it is then fine

I think it's an offboard wiring  / switch problem, PCB looks fine as far as I can tell. If it was me I would connect 2 jack sockets to the in and out and test the PCB without footswitch etc

Took the CI in out and connected directly to the JI off the PCB just twisted together. Nothing but a slightly thin sound which was what i was getting before. Must be a Main Board issue?

I wonder if it's worth taking out the Bias pot and trying a spare Alpha pot wired in there?

Fuengi

ICBM said:

Fuengi said:

It's clear, no short to the casing. 

On testing the continuity through the switch JI is switching between CI and G.

Do you mean CI is switching between JI and G? If so that's correct. The circuit input should be connected to the jack when the pedal is on and to ground (to mute noise) when it's bypassed.

If JI is actually switching to G then there's something very wrong with the switch wiring! Unless it's switching to JO (correctly for bypass) and the output jack is shorted instead.

Sorry, that is what I mean. CI is switching between JI (on) and G (off). So that's correct?

I pretty sure it's the board. Is there a way to test the IC's? I've got an old Chorus pedal with some spare IC chips in any point in swapping those in to test what happens? Also worth trying the bias pot?

Danny1969

I could be wrong but from what you have measured the opamps are more or less what I would expect.  Generally when an opamp goes bad it's because it's been reversed biased in terms of +VE or inputs higher than output ...that often leads to shorts which are obvious 

Check grounds  in and out are shorted together 

Now it would be handy if you had some kind of audio probe because you can't use a multimeter using DC Ohms to buzz through a capacitor coupled audio circuit ... caps block DC so you need an actual audio source, 

You can chop the end of a guitar cable, connect the bare screen wire to the pedals ground and then use the hot conductor as your audio probe but it's a pain constantly hitting the strings to get signal so chopping the end of an ipod aux cable is a better idea ....connect the ground of the aux cable to the pedals ground and use one of the other 2 wires as your probe ... doesn't matter which as they are just left and right and you only need one. Play a song and that's your audio probe

Then start at the output of the pedal when it's connected to an amp .... start at the jack out socket, if good move to any pot that sets a master level ... signal will be other side from ground or you can test on wiper in the middle ... then move to output of last opamp before output (pin 1 or 7 of a TLO72 ... then move to inout of opamp (pin 3 or 2 or 5 o 6 depending on circuit. You will then find where signal is lost between input and output, then you can generally investigate in exactly the right area

It's all good experience

Cookiemonster

I would unwire it from the switch. And try it that way. If it doesn't work, reflow the solder and try again. 

LastMantra

Are you not going to need to fine tune the trim pot? I've built pedals that needed lots of tweaking to get it working properly. 

Fuengi

LastMantra said:

Are you not going to need to fine tune the trim pot? I've built pedals that needed lots of tweaking to get it working properly. 

I do wonder if that's it. There is such range on it I don't really know how to go about it. 

I'm tempted to take out that trim pot and wire an alpha pot in temporarily to see if I can get it biased easier. The trim pot that come with the kit just doesn't seem to have any significant affect, it just spins and spins. 

Hard to know if that's the issue or some other fault.

drofluf

If you have a looper can you use that as the input? Then turn the trim pot to one extreme and slowly adjust until you get the "right" result.

Fuengi

drofluf said:

If you have a looper can you use that as the input? Then turn the trim pot to one extreme and slowly adjust until you get the "right" result.

Yeah, I think I will give that a go. 

Fuengi

Have had a chance to take another look and separated the circuit from the switch and tested that alone. The circuit is providing a signal, but no defined effect, other than to thin the sound. No swoosh or movement, it's like it is stuck in one phase.

I've got some spare IC's from an old chorus pedal, would i damage them if I swapped them over with the phase IC's to see if they had any effect?

Danny1969

I would take a really good look at the FET's .... the opamps are basically being used as gain blocks so I don't think it's those. 

Often with these things it's something simple that got overlooked