Missing OCD cap, oh no!

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FacemeltingSolos

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So a friend of mind gave me his old OCD pedal (V 1.7). He'd lost the screws, one of the knobs and apparently a capacitor! It's labeled C8 and I'm pretty sure it was a tantalum cap based on pictures, though some may have used electrolytics. Anyway, does anyone happen to know the value? :unsure:
 
You can check out the schematic for the ADHD project in the shop. The component designations might not be exactly the same, but if you can follow the schematic and trace it out on the board, you can pretty easily figure it out. If you have a multimeter with continuity testing abilities that will help a lot

Edit: C8 on the adhd is attached to the tone pot. That might narrow your search a bit. Just verify if your missing cap has traces to lug 3 of the tone pot.
 
I saw them with electrolytics in some photos, and with something under the board perhaps in others. Maybe you could look at the other electrolytics values and deduce what the value is comparing it to schematics.
 
swyse said:
I saw them with electrolytics in some photos, and with something under the board perhaps in others. Maybe you could look at the other electrolytics values and deduce what the value is comparing it to schematics.
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Effects database haze it as a 220uf. Another schematic has it as a 47nf. My schematic is a 22nf.Not sure why an electro would be connected to the tone pot though.
 
Just a thought - was there definitely a cap attached there in the first place? You'll often find "missing" components on pedals which have been consistently updated over the years. Does the pedal work? How could a cap have become detached??
 
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I came to say that ☝️. It‘s not uncommon throughout electronics. Sometimes, a company will sell several option packages, which may require additional components. You’d think a single cap wouldn’t be worth the trouble, but if you sell 10m refrigeration units worldwide it could add up.
 
I see on some gut shots it goes to the switch, curiously its the positive side though, which I would expect to face the op amp instead of the switch if its the capacitor I think it is?

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It also doesn't really correlate with the available schematics, I know the pedal pcb one is version 2.0, but the others are similar with nothing going to switch pin 1, but this looks like the capacitor goes to switch 1, with the resistors going to 2 and 3 as expected, but I notice the signal comes off of pin 3. Anyways, I would assume this is your 1u or 10u (depending on version) DC blocking capacitor, check continuity with the negative pole, closer to the pot and pin 7 on the IC.

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Does it work without the cap? That would help narrow down if the cap is in the signal path or a filter. There's a 1uf polarized cap in the signal path of some versions of the OCD.
 
Hey, thank you to everyone responding! I had a busy workweek and I came back to this whole thread. I think I'll need to check where the email alerts are sending to. 😅

HamishR said:
Just a thought - was there definitely a cap attached there in the first place? You'll often find "missing" components on pedals which have been consistently updated over the years. Does the pedal work? How could a cap have become detached??
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I'm being nice when I say my friend is extremely rough with his pedals. This one came with the base unscrewed and crunching into the pcb. I've fixed many a broken Boss jack for him. And yes, he plays acoustic guitar. Every other gutshot of this version I've seen (1.7) I've seen has a cap there, either barrel or tantalum. Also, there are leads coming out of the other side. But who knows? They apparently changed this thing all the time!

swyse said:
I see on some gut shots it goes to the switch, curiously its the positive side though, which I would expect to face the op amp instead of the switch if its the capacitor I think it is?

It also doesn't really correlate with the available schematics, I know the pedal pcb one is version 2.0, but the others are similar with nothing going to switch pin 1, but this looks like the capacitor goes to switch 1, with the resistors going to 2 and 3 as expected, but I notice the signal comes off of pin 3. Anyways, I would assume this is your 1u or 10u (depending on version) DC blocking capacitor, check continuity with the negative pole, closer to the pot and pin 7 on the IC.
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That's the one, but mine is on the negative side! 🤣 Also might be missing C2, but that one also looks like it might've just been filled in. I'll see about that.
Diynot said:
If nothing else, post up a pic of the board
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You got it.

EDIT: Correct version
 

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Wow! So glad I'm not anything near your friend's feet! Tell him to take deep breaths and think calming thoughts before he steps on a pedal...
 
HamishR said:
Wow! So glad I'm not anything near your friend's feet! Tell him to take deep breaths and think calming thoughts before he steps on a pedal...
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Oh heck no! I already got this thing and a Boss RV-6 for free! Only a jack, cap, or wire here and there. More violence! More, MORE!
 
Upon reflection, while I abhor violence towards any pedal I myself have made, I find myself agreeing with your sentiment in general. Especially when the object of said violence in this specific case has been an OCD, a pedal from the most fascist of pedal producers, and have to agree with you wholeheartedly.
 
HamishR said:
Upon reflection, while I abhor violence towards any pedal I myself have made, I find myself agreeing with your sentiment in general. Especially when the object of said violence in this specific case has been an OCD, a pedal from the most fascist of pedal producers, and have to agree with you wholeheartedly.
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Oh yes. That guy is a bad take factory, and that's being nice. To be completely truthful might violate terms of service.
 
Alright, so I've seen one post about this cap somewhere on the ether, and they're saying the original was a 2.2uf electrolytic, and they were talking about switching it to tantalum or whatever. And then others don't have it at all? I swear, this design is so inconsistent. The handwriting in mine is 1.7, but the board is 1.4. I mean I get it, but it's all quite silly.
 
I have an OCD modeled in LTSpice, I believe v1.4 was the schematic I used, I omitted the switch, but you can see how using a 1u or 10u cap affects the frequencies here. I would say the capacitor is mostly just there to block the DC voltage from the op amp stage from volume control/output as the difference is very small. I'm an idiot so the labels are all over the place but C3 right after the second op amp in my schematic should be your C8.
 

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