@billy
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Low output volume could be a number of faults
Q4 drain does need to be biased to between 4.5 to 6v
Q5 is an output buffer and as you know doesn’t require biasing
Check the code on your trimmer is 104
TR4 is to set the bias voltage on Q4 drain pin it doesn’t directly affect the volume but it will if Q4 is not biased correctly and doesn’t amplify the signal as it should
I think you have your FET pins mixed up on your voltage readings,
Your drain and source pins are the wrong way around
If Q4 is incorrectly biased it will also affect Q5
I did a wee bit of work on this version to get a better range across the gain pot a while back so the circuits good
You can also check TR4 is working with no power to the circuit check the resistance value between the 2 outer pins and that it changes as you turn it
All your component values and orientation that I can see look correct
Did you bias the transistor drain pins to between 4.5 to 6v and where did you get your transistors from
Once it’s working if you can post all voltages for anyone else that may run into this type of problem it’s always good to have working voltages
Well spotted Barry I never even noticed those joints I was too busy checking component values etc a few do look as if the solders not fully melted onto the pads so hopefully that’s it
Your input and output voltages on the brick pins 3,5 and 6 look very low to me
I’m taking it you get 0v on pins 2 and 4 ground as it should be
Incorrect voltage can be a cause of oscillation
What voltage do you get on IC1 pins 1, 3 and 5
If the voltage is low particularly on pins 3 and 5 check the voltage at the voltage divider junction where R11 and 12 are joined which should be VB around half input voltage
All your component values and orientation look correct It’s difficult to make out R3 clearly but as far as I can tell its 200K red black black orange brown the orange band just doesn’t look as bright as it usually is because of the reflection I think
What are you powering it with and what voltages are you getting to the BTDR 3H pins
It’s a good idea to post some nice clear images of the board so that all component values and orientation can be clearly seen and offboard wiring traced
It’s very easy to miss something I know I’ve missed incorrect values etc even after checking numerous times
Another one? and another great looking one at that
I’m gonna have to get into these nostalgia tone builds the boards look excellent
There’s been some very tidy professional looking builds posted….
Maybe I shouldn’t haha I’m not going to top these builds
Excellent work all round
On another note why does your build make me feel hungry? it does look tasty right enough
Post voltages for every pin of all ICs
It seems strange that you’re getting VB on output pin 7 of IC3 and 4 but not pin 7 of IC2B where VB originates, so all pin voltages might highlight something
Your pin 8 readings should be more or less the same as you can see in the power section bottom left of the schematic, voltage to all pin 8s comes after C21
It’s just a process of elimination from your voltage readings it does appear that your problem lies in the power section I would double-check all component values and orientation we know that you’re getting 9v in you’ll drop around 0.4v through D9 so your problem is likely in the power section or something it connects to
Make sure all of your op amps are securely clicked into their sockets, where did you get them from I’ve seen a few posts of late with dodgy Tayda TL072s
You could also remove the op amps from their sockets and check voltages on the empty sockets to see if that makes a difference
Op amps as you know are active devices if there’s a solder bridge somewhere it may only be connected with them in socket
So if you check the voltage on the empty socket and get good voltages either the op amps faulty or there’s a bridge or some other problem causing it to malfunction
Yes that’s correct on both points Richard
Just for info a 3K3 would give you a fairly bright LED most folks use around 4K7 so depending on how bright you like your LEDs you can use any value from 1K8 upwards
I prefer dim LEDs and use 10K with mine if it’s a standard type LED
Take your time and enjoy creating your first pedal
A dip switch is just an on/off spst switch so I don’t suppose it really matters apart from if you’re labelling the enclosure and whether you want ON to the left or right
Number 1 is the way they’re oriented in the after blaster build doc image so I’d go with that it also just looks right to me
Have a look at the easy order switcher 4PDT footswitch build doc here Gavin that shows you how to do it
Looks great
I particularly like the fact you haven’t obscured any of your labelling I don’t know why but for some reason it annoys me when there’s a knob or switch hiding parts of an enclosure image
It’s a great little circuit I’ve used a lot on older effects with low output volume like the electric mistress I usually stick one in series with the output to bring the volume up to unity I’ve never had any noise issues with any I’ve built
For retrofit filtering I place the filter caps directly onto the DC jack lugs I use the small micro miniature electros which are 5mm in height so much smaller
That looks great
Those Marshall style knobs make it pop with the gold 3PDTs
This is another very pro looking build I’ll need to up my game some
I’ve never been a fan of ribbon cable but I might be changing my mind after looking at your build it definitely gives it something
That’s a good looking build very nice indeed it looks really professional
I’m liking those switch caps and the knobs they’re a perfect match with the enclosure colour
R28 must be your problem it’s difficult to see but it looks like a 10K ohm – brown black black red brown or a 1K ohm – brown black black brown brown and not a 10 ohm – brown black black gold brown
You should have around 8.7v ish to pin 8 of all your ICs and around 4.5v on IC1B and IC2B pin 7
