@billy
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Here’s a PDF for continuity testing
https://drive.google.com/file/d/176vVBWeRaSQ0QvZlnozjKHE6AeHsvxFP/view?usp=drivesdk
Select the continuity function put your black probe in the meter COM socket and red in the ohms resistance socket if its an auto ranging meter select the ohms function and press the range button to select continuity mode
Once selected touch your 2 probes together and it should beep confirming it’s in continuity mode
R13 looks like a 6K8 instead of 1M that would allow more signal to go to ground
Not sure looking at the build doc I’ve got it’s 1M on the schematic and BOM but double checked I had the most up to date and the second one does show 6K8 in the BOM
Rusty you could just compare schematics and component values
You’ll find they are in the same position e.g. in the op amp feedback loop
Follow from input to output and compare
You’ll see for example R3 in the gpcb schematic is a 1M from 4.5v (VB) to op amp pin 3 the + input in the other schematic its R5
R5 in the gpcb schematic is a 1M resistor in the op amp feedback loop between pins 6 and 2 in the other schematic its R4 changed to a 1M potentiometer wired as a variable resistor but still between output pin 6 back to negative input pin 2
There is this thread on the old forum scroll down to 2nd post
https://guitarpcb.webs.com/apps/forums/posts/search?query=Emexar+mods
What I would normally do is either print that PDF page out custom size of the pcb or take a snapshot and custom size it in my editor I use gimp
With this I would probably just dry fit the pots and measure it myself because the layout is square so all you’d need to do is measure vertically and horizontally
I must admit I barely ever use a drill template it’s just measure, print it out and see if it fits then if it fits I just put paper masking tape on the enclosure and mark it on there making sure there’s room for everything else dc jack, 3PDT in and out jacks etc
R18 looks like a 33K not normally significant but with the mid scoop mod may cause oscillation idk
Unfortunately as you know feedback can be caused by a number of things if I’ve eliminated all external causes a non technical method I use to try and find it is probing solder joints with my finger tips and the old wiggling wires test to see if it changes quite often leading me to the source
As Cybercow said audio probing to see if you can find where it starts is a good idea
I too have never had problems with the 3PDT board of all of the one’s I’ve used it’s by far my favourite especially with combo builds so if all solder joints are good and it’s wired correctly I’d personally rule that out
Just for info the S4, 5 and 6 pads are used for the main pcb bi colour LED if you use one
S5 goes to 3PDT lug 5 ground and S4 and 6 are grounded by S5 to which ever colour the 3PDT is switched to when S4 connects to S5 effects mode colour, S5 to S6 bypass colour as you say per the build docs if using the 3PDT board you can ignore them and the main pcb CLR and LED
Post some nice clear images of both sides of the board and your offboard wiring to jacks 3PDT etc so that we can trace it
Looking at the schematic I’d try taking your output from volume lug 2 leaving everything after vol 2 the boost section off the board
Don’t solder vol 2 to the pcb just put a wire from it to the out jack tip I’d imagine you may lose volume without the boost
Easy enough to try and see how it sounds if it doesn’t sound good populate the boost section
If you simply want to omit the extra switch you’d need to connect vol 2 and R16 continuity check to see where vol 2 and R16 are connected to the switch pads if they connect to different SW1 pads jumper them
If it’s loud it doesn’t sound normal they are high gain pedals so you may get some noise from your pickups, leads etc or a little hum when not playing or standing facing and too close to your amp there are several things that can cause noise
Check your grounds are all good and your audio wires don’t run paralell or close to your power and ground wires If you have to cross them do it like this +
You can also get unwanted noise amplified through the circuit with cheaper power supplies that aren’t regulated or filtered
The ratt circuit does have power filtering the 47u C11 check C11 solder joints are ok
There’s also the possibility of DC leaking into the audio path as I say several possibilities
Try turning the trimmer in small increments to see if the noise improves and make sure power and ground wires cross over like this + and don’t run paralell like this =
If you haven’t already reflow the solder joints on the depth pot
It could be several things causing the noise and or oscillation
Art
The battery overheating usually means a dead short (ground connected to power 9v) post a picture of your power wiring to the battery and dc jack if you used one so we can trace it, check your power and ground wires aren’t connected somewhere or touching in some way
Use your meter to continuity check the 9v and gnd pads on the pcb this will quickly tell you if you have a short, you don’t need to power the circuit, you can also continuity check your DC jack power lugs don’t have continuity with ground – your ground lug with board 9v lug and ring with battery 9v lugs or for the battery just check the two connections on the actual snap don’t have continuity see below you don’t want continuity on the green lines
All your values and orientation look correct to me
We’d also need to see the in jack stereo socket I can only see the out socket
If you’re using one what type of power adaptor is it
Once you get it fired up you’ll love it, it’s a glorious circuit
We need pics can’t really help without seeing it post pics of both sides of the board so that we can clearly see all components and trace the wiring and inspect solder joints
No one’s here to judge anything we all started somewhere none of us were born making perfect pedals that’s for sure
Some information on 3PDT wiring on page 21
https://drive.google.com/file/d/1sGUR1g84vk01AIF1ut310IcH5G2i8L4J/view?usp=drivesdk
