Hello forum,
I am hoping someone can help a beginner with assembling a pedal.
I purchased the kit from Musikding, it is made by TH Custom and designed by Merlin Blencowe.
Populating the circuit board was easy, but the instruction sheet stops there - it does not explain how to wire up the battery, DC jack, potentiometer, switch, input and output jacks, etc.
The circuit board is marked (see photos) but I'm not sure how to interpret those markings.
Could someone point me in the right direction? Maybe someone has a photo of the completed device?
Also, the enclosure that came with this kit does not include standoffs or holes for mounting the PCB to the chassis, so it seems it will float freely... What should I do about that? Insulate it with foam?
Thanks in advance!
See attached photos
https://www.madbeanpedals.com/tutorials/downloads/StandardWiring_MBP.pdf
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Thanks for the link jimilee! That will at least get me started!
Another question: The DC jack has three tabs, but only two contacts, right? So two of the tabs are internally connected?
Thanks again!
A switching DC jack has 3.
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Well, I have the potentiometer wired in now, thats at least some progress.
Quote from: jimilee on March 28, 2023, 02:42:21 AM
A switching DC jack has 3.
Took me a moment to understand, but now I get it: When the power supply is plugged into the jack it disables the battery. Now I just need figure out which is which... Should be able to determine that easily enough with a multimeter.
I know this shouldn't be complicated, but I'm still uncertain of how to wire up the rest.
The main board has:
1 "in"
1 "out"
3 "GND"s (ground)
2 "+9V"s
The switch board has:
"JI" = ____ in?
"JO" = ____ out?
"BI" = ____ in?
"BO" = ____ out?
Two "+9V"s
Three "GND" (ground)
Do I understand correctly that I only need to hook up one GND on each board?
Quote from: Matness on March 28, 2023, 03:11:45 AM
Well, I have the potentiometer wired in now, thats at least some progress.
Quote from: jimilee on March 28, 2023, 02:42:21 AM
A switching DC jack has 3.
Took me a moment to understand, but now I get it: When the power supply is plugged into the jack it disables the battery. Now I just need figure out which is which... Should be able to determine that easily enough with a multimeter.
I know this shouldn't be complicated, but I'm still uncertain of how to wire up the rest.
The main board has:
1 "in"
1 "out"
3 "GND"s (ground)
2 "+9V"s
The switch board has:
"JI" = ____ in?
"JO" = ____ out?
"BI" = ____ in?
"BO" = ____ out?
Two "+9V"s
Three "GND" (ground)
On the switching jack, the ground is the l shaped lug. Immediately to the right is the DC power supply, to the right of that is the battery. That one isn't necessary if you don't plan on using a battery.
JI=jack in
JO= jack out.
BI=board in
BO=board out
Extra +9vs and grounds are just helpful sometimes. You don't necessarily have to use them.
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Quote from: jimilee on March 28, 2023, 03:17:44 AM
On the switching jack, the ground is the l shaped lug. Immediately to the right is the DC power supply, to the right of that is the battery. That one isn't necessary if you don't plan on using a battery.
Thanks for that tip, I would prefer to skip the battery.
Just to make sure I understand correctly I've uploaded another photo.
You're saying that the upper lug / middle lug is the one for the DC power supply, and that I can completely ignore the lug furthest from the L-shaped one (far right in the photo)?
Quote from: jimilee on March 28, 2023, 03:17:44 AM
JI=jack in
JO= jack out.
BI=board in
BO=board out
Excellent! Now its beginning to make sense!
I'll likely have a few more questions yet though, since this board looks too fragile to tolerate much desoldering/resoldering I want to try to get it right the first time.
I think I have the two PCBs wired together now.
Assuming that:
"BI" on the switch board = in FROM main board (wired to 'OUT' on main board)
and
"BO" on the switch board = out TO main board (wired to 'IN' on main board)
Quote from: jimilee on March 28, 2023, 03:17:44 AM
Extra +9vs and grounds are just helpful sometimes. You don't necessarily have to use them.
So in theory it shouldn't matter which GND or 9V+ point I choose on each board?
Duplicate connection points on the same board are redundant and purely for convenience?
Do I need to connect GND and 9V+ to both boards? Or only one?
Your advice on this is hugely appreciated! Thanks a lot!!!
So I made some guesses and seem to have guessed wrong...
I connected the ground wire DC jack ---> Output jack sleeve ---> Switch board GND ---> Main board GND.
I connected 9V+ to main board and to LED side of switch board.
Wired everything else up according to the link jimilee provided at the beginning of this thread, which all seemed to make sense... The only thing I didn't do was make any connections between switch poles, being under the impression that the switch PCB was already making those connections... I'll remove the board tomorrow and follow the traces to see whether this is the case or not.
Plugged in DC power and hit the switch... LED did not light up.
Plugged guitar and amp in - with pedal off(?) audio passes through unaltered...
With pedal on(?) there is no audio, and a quiet high pitched whine which which disappears when I turn the potentiometer yet won't return at any position? I unplugged it immediately rather than risk damage.
I also notice that the switch PCB seems to have an empty space for a resistor right before the LED...
Unfortunately the instructions that came with this kit don't mention or show photos of the switch PCB at all... Its as if a page was missing - they go straight from populating the PCB to "You now have a boost pedal"!
https://diy.thcustom.com/?wpdmdl=3881 (link to instructions)
So I'm a bit lost and will wait for advice here before proceeding.
Looks like I won't complete this project tonight, but I look forward to trying again tomorrow if I haven't fried any components...
Can we have some clear close up pics of where you're at? There's a lot of information the re.
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Quote from: jimilee on March 28, 2023, 12:06:20 PM
Can we have some clear close up pics of where you're at? There's a lot of information the re.
See attached photos.
First photo is most useful - I drew a wiring diagram, since the real-world wires aren't so easy to follow visually.
Forum won't let me put them all in one post, so additional photos will follow in 2nd post.
Additional photos (see previous post also)
I'm going to wait for expert advice before doing anything, but my guesses:
- The switch board may need another 9V+ connection?
- The LED is missing a resistor of unknown value
- I may have also made a beginner mistake which will be obvious to Jimmilee
Did you check out the link I gave to the instruction sheet?
Am I mistaken in thinking that the instructions are incomplete?
The switch PCB is double-sided, I can't follow all of the traces now that the switch is soldered but I assume that all necessary switch connections are being made by the PCB.
The instructions look complete, some people don't put wiring instructions I. The build docs, some do.
The I put jack is a a little blurry, so here is how it's supposed to go.On the input jack, the ground is the inner most lug, the out lug is the outermost or the bottom of the stack. The CLR is anything from 2k to. 10k with 4.7k being the most common. The DC jack looks right.
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Quote from: jimilee on March 28, 2023, 08:17:08 PM
the out lug is the outermost or the bottom of the stack.
One jack is mono, one is stereo. The stereo is the input, and the mono is the output, right?
The stereo jack is kind of strange, the bottom of the stack connects to ring, the middle of the stack connects to tip. The top of the stack is shield as expected. I connected the output to the tip.
I'm thinking the jacks must be wired correctly, because with the switch off(?) audio does pass through.
Does the switch board need another DC connection?
I ran a 9VDC wire to the LED hookup on that board, but maybe I need to run one elsewhere on the same board?
Or maybe adding the resistor will complete the circuit? I also ran a 9VDC wire to the main board.
I'll install a resistor for the LED and see what difference that makes.
Thanks for all your advice!
Absolutely, I'm happy to help. Thanks for the input clarification on the input jack. The switch board doesn't need any more 9vDC connections.. As a matter of fact, if you put your DMM on the continuity setting, you'll find they're already connected.
If you still have no sound, check all your components to make sure they're all in the right place and your polarities are all correct.
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I added the resistor, now the LED does light up.
When pedal is off audio passes through unaffected.
When pedal is on there is no output at all.
Polarity of all components (electrolytics, diodes) is correct according to the markings on the boards. I just triple-checked. (see attached photo of PCB from Musikding website)
Orientation of IC and Transistors is correct according to the photo on the instruction sheet.
https://diy.thcustom.com/?wpdmdl=3881
Yet still no output...
I've checked for solder points which might be close enough to arc, reflowed the joints which were questionable, brushed the surface to dislodge conductive debris, etc...
What else could it be?
Ok, we're making progress. Were you able to reflow both sides of R4?
Audio probe is the next step.
Here is a really basic one. If you have a 100n cap and extra wire, you can solder it to the out jack you have there already.
https://www.reddit.com/r/diypedals/comments/lqq3ku/diy_audio_probe_how_did_i_not_have_one_of_these/?utm_source=share&utm_medium=ios_app&utm_name=ioscss&utm_content=3&utm_term=1
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Quote from: jimilee on March 28, 2023, 11:42:52 PM
Ok, we’re making progress. Were you able to reflow both sides of R4?
Audio probe is the next step.
I reflowed both sides of R4 as per your suggestion, as well as many other joints even though they all look normal. No change at all. I tested continuity between all GND points and chassis (all 0.0 ohms), and between all 9V DC points (0.0 ohms). Resistance between 9VDC and GND is 4.7k... Does that seem normal?
I also tested all resistors (not for spec, just for continuity) none are open. Tested all capacitors (in circuit) all normal values except that one of the 10uF reads as 60uF... Probably a quirk of the circuit, and that shouldn't result in 'no output' even if the capacitor is defective.
I tried testing the diode in circuit, couldn't get a reading from it - 0V in both directions... Should I pull it out and test it? Or is that unlikely to be the culprit? If faulty I'd have to replace it with a 1N4007 which is the only silicon diode I have on hand.
I will build the audio probe as you suggested, into the output jack of the pedal.
I have a 100nF capacitor, so no problem there.
Is there any risk of damaging the circuit if I accidentally probe the wrong spot?
I'll set up a jig for audio probing (signal source and amplifier) later on this evening and report back.
Uploading schematic for convenience
Hello. Na, don't pull anything out of the board until we probe it, don't want to lift any pads just yet.
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Did some initial probing, results are discouraging...
With pedal switched on (LED lit) I detect (unamplified) audio at the following points:
Main board:
"OUT"
Switch board:
"BI", JI" and three switch lugs (see photo)
No audio at the potentiometer. No audio from any pin of the IC or transistors.
No amplified audio anywhere.
See attached photo for clarification - I've marked points where I can detect audio with a yellow circle.
Do I have the wires between the two PCBs reversed?
I've been assuming that:
"BI" on switch goes to "OUT" on PCB
and
"BO" on switch goes to "IN" on PCB
Maybe I have that backwards?
Board in goes to the in of the circuit board and board out goes to the out of the circuit board.
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Thanks jimilee!
I'd just finished swapping the wires when your message came through.
The pedal now seems to function as intended, except that I have the potentiometer reversed.
I can not overstate how helpful you've been! Your guidance was hugely appreciated!
Without you pointing me in the right direction I'd still be lost!
The only other thing I'm wondering, is: I have a collection of germanium transistors harvested from late 60s electronics which I've been saving with the intention to some day build some fuzz pedals. To get advice on which transistors are most useful for this should I start a new thread? If so, which sub-forum? The "Beginner's Paradise" category, or elsewhere?
Thanks again!
Quote from: Matness on March 29, 2023, 09:10:46 PM
Thanks jimilee!
I'd just finished swapping the wires when your message came through.
The pedal now seems to function as intended, except that I have the potentiometer reversed.
I can not overstate how helpful you've been! Your guidance was hugely appreciated!
Without you pointing me in the right direction I'd still be lost!
The only other thing I'm wondering, is: I have a collection of germanium transistors harvested from late 60s electronics which I've been saving with the intention to some day build some fuzz pedals. To get advice on which transistors are most useful for this should I start a new thread? If so, which sub-forum? The "Beginner's Paradise" category, or elsewhere?
Thanks again!
Woohoo! Glad you got it up and going, enjoy!
Fuzz transistors are out of my wheel house. Start a new thread and see who has info.
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