DOD 250 OVERDRIVE type pedal I’m trying to recreate. Need insight

[PAGOON]

It’s a one knob overdrive called mercy phuk I’m just wondering on a few components the two tantalum capacitors are brown black and green with a splash of blue paint on the top…. I’m also wondering what the op amp maybe probably a 741 … and. I’m wondering Most of all I believe it uses two transistors for clipping but the part # & values were sanded off… I can see part of the numbers … I’m just looking for a insight on the two transistors I thought they would be mosfet… but I do not think they are…the part number that I can see on one is 2n4401 and the other all I see is BC20? Anyone know what the bc20 might be???

 

[z2amiller]

I think the two tantalum capacitors are 1uf:

https://www.reddit.com/r/AskElectronics/comments/eb5s66/what_is_this_colorful_capacitorlike_thing

It looks like it also has LEDs for clipping as well as what looks like a germanium diode bottom right.
(1N34A maybe?)

If you are brave about desoldering, getting the component values of everything that is hidden/sanded
should be pretty straightforward.
(You could use a cheapo LCR/transistor tester like this to pull the values : https://www.fnirsi.com/products/lcr-p1,
which can tell the difference between different transistor types and give you their approximate gain
values and pinout which can help you narrow down what you're targeting for a replacement)

Once you have the schematic mapped out it'll also be obvious what kind of op-amp you have.
(At least, a single op-amp vs a dual op-amp - you're right that a single might be a 741)

 

[jwin615]

May be a 2SC20(SC20)
Which is a npn si
Led/ge Asym clipping.
The BJTs are probably input and output boost/buffers or a 2 transistor fuzz. Hard to say without seeing traces.
What's the trimmer for?

 

[jwin615]

Oh. It's wren and cuff
Phat Phuk variant into a 250 probably.
Even has a "girth" switch.
Trimmer is "drive"

 

[PAGOON]

Yeah wow thanks folks ! I took picture of the capacitor and put it in google search and it said it was a 51mf but I’m not sure. … I think the trimmer is the volume or drive I’m guessing.. on tbe d250 the drive is a B1m and the volume is a10k . And I thought this was mosfet clipping and led clipping… I think that’s what google AI said about the pedal but there is that 9de and a 2n914 … I want to trace this circuit for everyone. I NEED to replace the foot switch so I will have the whole pedal apart when I do that… But I’m lost on those transistors… dang W&C they are sneaky… maybe your right I’m interested in if it’s a boost buffer… I need to look do pedalpcb make a 3pdt extra foot switch board?

 

[Feral Feline]

Hmm BC20x... mystery.



Definitely Not BC20 on its own, a Power MOSFET — BC20 is not a TO-92 package, but a TO-220, like those for IRF510 and IRF520...

Not BC201, BC202, and BC203 which are epitaxial PNP silicon planar transistors of ultra-miniature design in U 32 plastic package (as found in hearing-aids).
— HOWEVAH... the BC201 is also available in TO-92...

Probably Not BC204, BC205 and BC206 are silicon planar epitaxial PNP transistors in TO-18 epoxy package. A general amplifier.
BC204, which came in the TO-18 mushroom cap package, floating around eFlay for about $4–8 ea...

LIKELY... BC207, BC208, BC209 are TO-92 packaged general purpose audio amplifiers, silicon planar epitaxial NPN transistors (previously available in TO-18 packages for extra mojo). BC207 are/were still/recently available.


Duh, I just looked at the pic and have to agree with Jwin615 — SC20xx ... SC2001 or SC2003 or SC2026 or ?






I love the components layout of the board. I wonder where W&C get the boards from, how they lay them out etc...

 

[jwin615]

Can't tell what the multiplier is but guessing black dot which would be 10uf

 

[PAGOON]

Thank you makes more sense… I wish I could get the 250 overdrive I build to sound more like the mercy…

 

[PAGOON]

I think the two tantalum capacitors are 1uf:

https://www.reddit.com/r/AskElectronics/comments/eb5s66/what_is_this_colorful_capacitorlike_thing

It looks like it also has LEDs for clipping as well as what looks like a germanium diode bottom right.
(1N34A maybe?)

If you are brave about desoldering, getting the component values of everything that is hidden/sanded
should be pretty straightforward.
(You could use a cheapo LCR/transistor tester like this to pull the values : https://www.fnirsi.com/products/lcr-p1,
which can tell the difference between different transistor types and give you their approximate gain
values and pinout which can help you narrow down what you're targeting for a replacement)

Once you have the schematic mapped out it'll also be obvious what kind of op-amp you have.
(At least, a single op-amp vs a dual op-amp - you're right that a single might be a 741)

I have a dca55 I eventually want to do that and trace the darn think it’s a sweet pedal … or I’m trying to make a better Pedal I took the D250 and put a old tinted glass OA 91 in one of the diode spots and a bas33 with a oa91 soldered to it on the other side it sounds good … I must have done a ton of diode swaps. But the mercy needs a new footswitch so when I do that I will try my best to trace it… but that one transistor is a mystery.

 

[jwin615]

2sc20 subs in 1963:
2Nl409A,2Nl4lOA,2Nl507,2Nl679,2Nl680,
2N2087,2N2192,2N2192A,2N2194,2N2194A
But, Fairchils didn't make 2SC20 as far as I can find (or any 2SCxx as those were mostly Japan models) so it's likely a BC208/9 B/C
208s are pretty common
I bet if you look up other wren and cuff traces, you'll see one a couple times. Or just use a gen purpose amp but around 250 hfe. Won't hear much difference given the clipping diodes.
Once you get it apart, take good clear well lit pics at a squared angle(directly above).
You can then flip one and juntapose them on a computer and flip back and forth.