[Billy]

The dot would indicate pin 1 Colin, sometimes it’s either a notch or dot and sometimes both if it’s both you’d go with the notch

Can’t really see the component side pictures they’re really dark with the shadow, we’d need to be able to clearly see all components, resistor colour bands and your offboard wiring so that it can be traced

Your TL072 readings are too high VR going into pin 3 should read half your power supply check what voltage you get at the junction of R17 and 18 the power supply  voltage divider you can use your meters continuity check to see where they join

What are your voltages on the PT2399 pins 1, 2, 3 and 4

Pin 1 should be around 5v with 2 half of pin 1s voltage and 3 and 4 are grounds or 0v

I think looking at your solder side R22 appears to lack solder I don’t have the build doc for the tap tempo which I’m assuming is your other board so don’t know what you leave out etc

*EDIT just found the tap tempo doc and see the notes on R22 so ignore that!

[Billy]

I can’t really see how you have your S4, 5 and 6 pads wired that may be the cause of your non blinking LED it sounds like it may not be grounding correctly

I’m still a little confused so just to be absolutely clear

Currently in or out of the box it doesn’t work

It did work except for your LED not blinking when you changed the depth pot, check nothing can short on the bare metal enclosure and you haven’t accidentally pulled a wire loose I’ve assumed your LFO works but

To check the LFO is still working with the speed pot at minimum IC2 pins should fluctuate between around 2.2v to 6v, set at maximum around 3.7 to 3.74v except pins 4 and 8 ground and power

 

 

[Billy]

Just to understand fully it works as it should until you put it in your enclosure is that correct? If not,

Your IC2 voltages are a bit off check your voltages either side of R5 the spacing pot fully CCW (turned down) should also get 7.7v to pin 2

Here are voltages from a working unit power supply 9.38v

I’d perhaps reflow those joints where you can see you’ve snipped the tops off whilst removing component legs R5 and 6 you can see the bottom joints are like that

[Billy]

What you mean I’ve wasted all that time learning the colour bands off by heart?

Nice chart and good idea though Cap’n

[Billy]

You’d need to know what you get both sides of the trimmer when you said all the way to the side I’d assumed all the way CCW

With a 100K trimmer across lugs 1 and 3, I get 96.6K turned all the way down I get 1.9R one side and  96.6K the other

The easiest way to check it if you can’t find a code 104 written on it is to check across the 2 outer lugs for total resistance

If you’ve done that across the 2 outer lugs and got that reading as Barry says it’s a 1K and would definitely affect the circuit

[Billy]

Trim pot will go from 0 to 100K depending on its tolerance

What model of multimeter are you using do you know it’s input impedance

[Billy]

Hi Colin,

Don’t think you’ve missed anything

I would buy the switch indicated and if it doesn’t fit you could just wire the switch in, with this one rather than a pcb mounted one at least you’d have the solder holes on the switch lugs and you know it’s the correct type

I don’t have the physical board to compare to the switch measurements, but looking at the switch datasheet the two poles are 8mm end to end with 5mm between the centre of each pair or throw

It’s definitely not easy to find the right type of momentary switch that’s for sure and the datasheet measurements are’nt the easiest to gauge

[Billy]

Sounds like something is pulling your voltage down which is obvously having a knock on affect on the rest of the circit

With power off check resistance between the 9v pad and bottom end of R32 where it meets R33, then check resistance keeping 1 probe on the R32 / 33 resistor junction and the other to ground

Also with power off check resistance from 9v pad to the bottom end of R31 where it meets C13

If you’re getting 9v at the top end of R31 then dropping 3v there could be a solder bridge around that area check those solder joints under magnification

When you look at that part of the circuit and from your description either there’s a bridge on R31 or something possibly C13, 14 or 15 is pulling power to ground

[Billy]

Check the colour bands on R31 they should be yellow, purple, black, gold, brown which they look like but it’s not easy to see clearly

Check the voltage on both sides if you’re saying it goes from 9v one side to 6v the other side of R31 try reflowing the solder joints of R31, C13 and C14

Use your multimeter continuity check to see where R32 and 33 connect at that point you should get half power supply (VB)

[Billy]

What’s the output of your power supply all your IC power pins are 2 to 3 volts lower

What are you using to power the pcb

I take it you mean all your grounds read 0v and you have +9v going into the pcb?

Check what voltage you get at the junction of R32 and 33 where they join, this is your voltage divider for VB half the power supply voltage so around 4.5v

[Billy]

Do you get 9v on the pcb +9v and ground pads

Continuity check all of your grounds making sure your in and out jacks are grounded

We need a nice clear picture of your DC jack so we can see the lugs

All of your component values and orientation look correct

I’m assuming you’ve tested other builds using this method successfully before, I don’t see any reason why it shouldn’t work just trying to make sure you’ve got power to the pcb and your in and out jacks aren’t connected directly together and audio is actually passing through the circuit before we look for circuit errors

Have you adjusted the trimmer TR1

These are typical voltages

 

 

[Billy]

Hi Joeri

Post some pictures of your offboard wiring to the DC jack, IN and OUT jacks and 3PDT switch so that we can trace the wiring and where it goes to

Do you get 9v to the pcb

R10 needs to be in place it is not for the LED

R34 is the LED current limiting resistor

[Billy]

Bas,welcome, the ratt is non inverting it’s output is in phase with it’s input

First stage goes into the + input of IC1 the second output comes from the source of Q1 making both stages non inverting

Here’s a link for Tonmanns Phase Determination guide on my google drive allowing you to work it out for any circuit

https://drive.google.com/file/d/1AGCu7TdhkkUw8hQppFhScZNhu744T1LM/view?usp=sharing

 

 

[Billy]

Yeah it’s on the schematic power supply section 1N4001

Barry’s obviously added it as further protection

[Billy]

Did you use a 3PDT board

If not and you haven’t already done it try a diagonal link from input lug 1 to lug 6 on the 3PDT switch

I had a loud pop on a script phase 90 tried both input and output pulldown resistors which didn’t change it as soon as I linked lugs 1 and 6 that cured it

 

[Billy]

More than likely a dry solder joint Vivek

This is interesting albeit I’ve tried this with mylars the difference wasn’t huge but still there

https://youtu.be/zHuW082TGXg

[Billy]

Nicely done Shane that looks excellent

[Author]

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