Seymour Duncan - 805 overdrive

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
roseblood11
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Post by roseblood11 »

i know it's just a simple tube screamer like circuit with added 3 band eq. But that makes definitely a very useful pedal, so retracing would be interesting.

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Post by sanfi4u »

Bumping this old request. If no schematic is available may be somebody who owns the pedal could share a few gut shots of it? Thanks!

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wilqen
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Post by wilqen »

Another year gone by ....
No one interested in tracing this pedal?
I think it would be an interesting build to say the least. Obviously being a tube screamer - not so interesting
BUT
3-band EQ ??? Very interesting.

How did they do it? Wish I had one. Wishing someone out there does have one & maybe at least could post some gut shots?

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jalmonsalmon
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Post by jalmonsalmon »

I am thinking maybe just add the marshall tone stack?
Image

teddeeh
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Post by teddeeh »

Hey guys.
I just bought one of these. So. How do i help out? I am daunted looking inside so i can either help by posting photos or..... i could be persauded to send to someone here on the premise of
1. Obviously i need to be able to trust the reciever so forum verification from some members would be cool
2. Have it as long as needed to sort parts and work out schematic
3. Returned to me, working, in condition it was sent

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Post by teddeeh »

Oh im in the uk too, so local would be preferable becuase of shipping costs. Overseas possiblly..

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Post by dv8r601 »

teddeeh wrote:Hey guys.
I just bought one of these. So. How do i help out? I am daunted looking inside so i can either help by posting photos or..... i could be persauded to send to someone here on the premise of
1. Obviously i need to be able to trust the reciever so forum verification from some members would be cool
2. Have it as long as needed to sort parts and work out schematic
3. Returned to me, working, in condition it was sent
Good gut shots of both sides will get the ball rolling. Thanks for your help

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Post by teddeeh »

Ok man. I have opened her up and it dosent look overly complicated. If you can help me, i will photograph and test parts, i do have a multimeter and a component tester.

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Post by teddeeh »

https://i.imgur.com/QHkZAPE.jpg
https://i.imgur.com/6MdBMRy.jpg

Pors and top of circuit
I will post other pictures in a bit.

I cant trace guys. But if someone is willing to help, i will test parts and follow someones guidance in helping trace and sort the schematic to this wonderful pedal out.
Attachments
Seymour Duncan - 805 overdrive guts 2
Seymour Duncan - 805 overdrive guts 2
Seymour Duncan - 805 overdrive guts 1
Seymour Duncan - 805 overdrive guts 1

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Post by teddeeh »

https://i.imgur.com/A5iul1h.jpg
https://i.imgur.com/becqI3N.jpg
https://i.imgur.com/PmuvQhf.jpg
https://i.imgur.com/XXj9Hzd.jpg

The two caps c11 and c12 are 47uf 25v
No components on the other side. Switch looks simple true bypass board.
Those are the guts. I am planning on shifting this pedal soon. But happy to have a poke if needs be. Im not good at tracing but can test components with my multimeter. And i do have a component tester.

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Post by teddeeh »

Started a main thread in boutique stomps dissected. Gut shots are there.

roseblood11
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Post by roseblood11 »

Great!

But please add all pictures as attachements here - there are so many old threads, that are more or less useles, because the external links are dead...

And it would be very helpful if you write a complete list of components, with the writen codes and the corresponding values.

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Post by teddeeh »

I can try to follow instruction but this is more for someone to help me.. i dont have the time at the moment to really dig in to this. I can help and take direction as im unsure for really digging my teeth into this. And as for tracking a schematic, id be just as much help performing surgery. But!! Im willing to try and help. If i have time ill do a component count and write codes but while i have the pedal as im planning on shifting it, ill do what i can. Ill try and keep it long enough till there is a working schematic and ill test it against the real deal if i can.
Attachments
ACC9F8DC-3E89-40D5-BB04-F36FDC93FB67.jpeg
D6583A27-C976-4983-BDEB-B3232D714FE0.jpeg
49F3EB53-877B-470B-A2F8-1A41A8297274.jpeg
F877C682-5124-42F2-B3AC-6BE860C08D86.jpeg

teddeeh
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Post by teddeeh »

Right guys. I kinda fucked the case just a bit so i guess im not selling this now. I have tried to get reqdings from my multimeter but im getting nowhere. I will happily post this to someone, preferably in the uk, to work it out. I will obviously want it back and working but i dont mind sending it to someone to trace and decifer.

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wilqen
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Location: Eastern Oregon, USA

Post by wilqen »

Hello. I'm in the US, but I'm actually very interested in this pedal and I'm willing to help. You've done the first step, You've taken some great pictures. The pictures show all the components and the circuit stands out on the board nicely.

As far as testing components sometimes that is possible with a resistor while it is in circuit, but not always, however all of the resistors I can see have the codes marked on them. Should be able to figure out what they are. The non-polar caps are going to be difficult because they are not marked at all and it is almost always impossible to measure them while they are in circuit. If some of them have to be removed from the circuit board to measure them it really won't be that difficult since they are surface mount.

Also this circuit is known to be basically a tube screamer and knowing that will help a lot. Give a head start actually. Some of the transistors seem to have non-standard labels, but it's a Tube Screamer, so it shouldn't be too hard to figure out what they are. Sometimes you have to make an educated guess.

I see that your last post is from February. Are you still interested in tracing this pedal? Do you still have it?
You mentioned that the case got damaged. Does the pedal still work?

If we get started on tracing it, perhaps others will join in .....

Will

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Post by nomminus »

Hi guys, my first time on here and amazingly I am perhaps able to help a little. There is a great resource that I use for identifying resistor values, but not in this case unfortunatly (lol), very simple and extremely effective for the older style through hole jobbies.

https://www.digikey.com/en/resources/co ... ode-4-band

Now this next bit may just confuse the issue; as I have not studied it against my SD 805. However, the 805 is basically a TS "boutiqued" by SD; so the basics should (I think?!) follow upon these lines:

http://www.geofex.com/article_folders/t ... sxtech.htm

Hope you guys find this of some use, I have to try and get involved in some way.


Paul

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Post by Ichabod_Crane »

I'm interesting to the 805 overdrive schematic. Did somebody got it?
Ok, basically it's a Tube Screamer. Then?
Just one dual opamp: https://www.onsemi.com/pub/Collateral/MC33178-D.PDF
There are six transistors. Maybe: one for the input stage, one for the output stage... The EQ is declared 90Hz +/- 11dB, 750Hz +/- 11db, 2.12kHz +/- 12db. Could be the other transistors used in a parametric eq? :hmmm:
The EQ pots seem 20k linear (B203S)
A 10k pot for the volume, and I guess a 100k log for the Drive? (A104S5). And a 100k sounds a bit weird to me. ANyway I can see even four diodes, for the clipping, probably in the feedback of the opamp. No code on it, but they are similar to silicon 1N4148.
The two 47uF caps should be in the power filter stage. One for the 9v and one for the Vref.
There are three smd electrolytic cap, I guess two 1uF and one 10uF.
https://www.electrosmash.com/images/tec ... iagram.png
The Tube Screamer has exactly those 1u caps as coupling, and the 10uF output cap.

I can't say more than this.

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Post by teddeeh »

I got one and sent it to the wizard at pedalpcb. He has traced and made a board so i would expect when he releases the build notes they will be there.

I also have a couple more pedals en route to him.

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wilqen
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my favorite amplifier: Frenzel Super Sportster
Completed builds: RM, Fuzz Face, TB, Muff, RAT, Dist+, KLON, KOT, Rub-a-Dub Reverb, 6 & 10 band EHX EQ, Keeley (Ross clone) Comp, Engineer's Thumb. Switched to etched pcb's this last year after 3 years of Vero builds. Presently developing 5-knob Engineer's Thumb with amplitude reduction LED ladder meter.
Location: Eastern Oregon, USA

Post by wilqen »

Hi guys,

Pedal-PCB does have this board in the works. Not out yet as of today (12/25/2019), but they have a waiting/notification list.

I still think this would be a great pedal to build and experiment with. Particularly working on the filter frequencies,
although I'm sure they have done plenty of experimenting to find the optimal 3-band filter settings.

I just built several projects from Pedal-PCB and I can say without any reservations that they make fantastic through-hole boards. Very impressed with their products.
They will publish the 805 schematic in the "build documents" so we will be able to take a look at the circuit once they post the docs (they will post the schematic/build docs when they make the board available.)

Special thanks to you all for posting the pics and sending in the pedal after buying it to have it traced.

Fulfilled my wish,
Will

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Post by phatt »

Maybe separate the tone section? You can then bypass the dirt and retain the tone section. If it's just a TS or similar a standalone tone pedal might prove more versatile.

Just by altering the sequence of efx can make subtle changes to how it sounds, i.e try inserting a tone shape Before and After dirt, it can change the outcome.

FWIW, I designed this some time back and it's proved to be very useful for my setup. I posted this schematic several times
(just search for PhAbbtone). I have lost count of how many I've build for local players with good feedback.
Have fun, Phil.
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PhAbbTone Ver4.png

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