MXR - Custom Badass '78 Distortion  [schematic]

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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 27 Jul 2011, 12:40

Finished schematic.

Image

Apart from the differend clipping arrangement it's just another DS1. I still need to check the cap values to complete.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 27 Jul 2011, 12:42

Forgot to mention, I have drawn all the transistors as bipolar but from the markings on them i don't know if there bipolar or fets, that is something else i nees to check out. I suspect Q7 to be a FETthough as it is the same arrangement as in the Distorion II.I
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Re: MXR Custom Badass '78 Distortion

Postby Güero 2.0 » 27 Jul 2011, 13:50

Ice-9 wrote:
coldcraft wrote:i wonder if those diodes could be forming a rectifier bridge. I've read that one way to prevent AC power from killing DC circuits is to have a rectifier in the way. It will still pass the DC just somewhat lower.


Your on the right track there Coldcraft, two of the diodes are forming a bridge with the two leds, then the other 2 diodes are switched in another config. I need to go over the clipping section to confirm the schematic before posting.


Nice job!
But, where are D3 and D6 ( Leds ) in skemo?
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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 27 Jul 2011, 13:59

Güero 2.0 wrote:
Ice-9 wrote:
coldcraft wrote:i wonder if those diodes could be forming a rectifier bridge. I've read that one way to prevent AC power from killing DC circuits is to have a rectifier in the way. It will still pass the DC just somewhat lower.


Your on the right track there Coldcraft, two of the diodes are forming a bridge with the two leds, then the other 2 diodes are switched in another config. I need to go over the clipping section to confirm the schematic before posting.


Nice job!
But, where are D3 and D6 ( Leds ) in skemo?


The top have of the bridge is U3 diodes SMD package, the bottom half of bridge is the 2 3mm red led's and the two diodes through R8 to the centre of bridge is U2.

I forgot to label those as i got disturbed at work and forgot when i got back to the schematic.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: MXR Custom Badass '78 Distortion

Postby coldcraft » 27 Jul 2011, 16:55

oh, I see. My suggest was thinking they were used on the power line for a bridge, but that's an interesting clipping arrangement. Reminds me of the Timmy, where the pairs are bridged. I wonder what its effect is, or if maybe it keeps the unit from popping when you toggle between them.
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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 27 Jul 2011, 19:40

I have just been reassembling the PCB and have noticed a capacitor that i didn't include in the schematic so there will be an update and final schematic to come. I have managed to get the values of the capacitors but as I measured them in circuit I cannot guarantee there ll 100% correct, but they do seem to check out. I won't gt time to do the final schematic untill after the weekend, but I will try and do a CAD version rather than hand drawn. Time to get this pedal on ebay and sell it for the next project :)
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: MXR Custom Badass '78 Distortion

Postby Beto Crazy » 30 Jul 2011, 18:17

What are the values ​​of resistors R1, R6, R9, R10, R12, R13, R27, R28, R29, R31?

R6 = 6K8?

R10 = 2K2?

R12 = 10K?

R31 = 3K9?



And the values ​​of capacitors C1, C2 and C3?
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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 30 Jul 2011, 18:33

R1 = 47K
R2 = 22OHM
R3 = 4K7
R4 = 2K2
R5 = 6K8
R6 = 6K8
R7 = 100K
R8 = 470OHM
R9 = 10K
R10 = 2K2
R11 = 1M
R12 = 10K
R13 = 1K
R14 = 100K
R15 = 2M2
R16 = 100K
R17 = 100K
R18 = 22K
R19 = 10K
R20 = 10K
R21 = 1M8
R22 = 10K
R23 = 470K
R24 = 3K3
R25 = 2M2
R26 = 470K
R27 = 10K
R28 = JUMPER ZERO OHMS NOT IN MY SCHEMATIC
R29 = JUMPER ZERO OHMS NOT IN MY SCHEMATIC
R30 =
R31 = 3K9
R3238.3K

C1 = 100UF ELECTRO
C2 = 100UF ELECTRO
C3 = 47UF ELECTRO
C4 = 47N
C5 = 0.29UF
C6 = 12N
C7 = 0.89UF
C8 = 1 UF
C9 = 45N
C10 = 47N
C11 = 1UF
C12 = 47N
C13 = 38N
C14 = 2UF
C15 = 100N
C16 = 72N
C17 = 100N
C18 =
The caps were all measured in circuit so some readings may be slightly wrong , foe example C9 read 45n I expect it too actually be 47n.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: MXR Custom Badass '78 Distortion

Postby Beto Crazy » 30 Jul 2011, 19:31

Is it more or less?
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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 30 Jul 2011, 20:24

Beto Crazy wrote:Is it more or less?


Close.
You have a a pair of diodes for D2 on the Badass it's only 1 silicone diode.
The clipping section is not the same as in my schematic, your DS1 has them different.
Your schematic adds in the switching for bypass but i didn't trace that out so am unable to coonfirm that.
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Re: MXR Custom Badass '78 Distortion

Postby Beto Crazy » 30 Jul 2011, 20:26

Some resistors in my schema names are wrong.

R1= R9
C1=C10

Connected to the base Q6.
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Re: MXR Custom Badass '78 Distortion

Postby Beto Crazy » 30 Jul 2011, 20:36

The connections between U2 and U3 are confusing, it is not possible to know whether they are switches connecting D3 and D6, in the scheme of DS1 is a pair of diodes connected direct.

The D2 is just a diode, but in the pictures, I imagined being a sort of 2 to 1.

The transistors Q2 and Q4 do not know if this is the connection between them.
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Re: MXR Custom Badass '78 Distortion

Postby Beto Crazy » 30 Jul 2011, 20:48

:hmmm: Vou refazer o meu layout, ainda têm muitos erros, :slap: mas as conecções são mais ou menos parecidas com isso.

Quem quiser ajudar, fique à vontade e entre na brincadeira. :P
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Re: MXR Custom Badass '78 Distortion

Postby Beto Crazy » 30 Jul 2011, 20:51

Ops!!! :hmmm: I'll redo my layout, still have many errors, :slap: but the connections are more or less like this.

Who wants to help, feel free and join the fun. :P
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Re: MXR Custom Badass '78 Distortion

Postby SirElwood » 30 Jul 2011, 20:58

For a while I thought I can't read english anymore.
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Re: MXR Custom Badass '78 Distortion

Postby ddpawel » 30 Jul 2011, 21:03

Beto Crazy wrote:Is it more or less?


Q2 is a FET
Q2 and Q3 - for THT use J177 or similar
Q7 - in this cofiguration looks like bipolar
C14 - maybe it's 47nf, but in many MXR pedals 10nf is occurs more frequently
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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 31 Jul 2011, 10:02

Beto Crazy wrote:The connections between U2 and U3 are confusing, it is not possible to know whether they are switches connecting D3 and D6, in the scheme of DS1 is a pair of diodes connected direct.

The D2 is just a diode, but in the pictures, I imagined being a sort of 2 to 1.

The transistors Q2 and Q4 do not know if this is the connection between them.


U2 and U3 are not switches , they are both a package of two seperate diodes.
D2 is a single diode in a 3 pin package (1 pin is not connected to anything)

I will be updating my schematic as soon as I get a bit time.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 31 Jul 2011, 13:45

Here is an updated schematic, It is the complete audio path. What is not included in this schematic ? 1. The entire bypass circuitry and switch along with the led for bypass indication. 2. The circuitry for the led which indicates the crunch mode is engaged.

Image
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?

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Re: MXR Custom Badass '78 Distortion

Postby Ice-9 » 31 Jul 2011, 16:20

I am a bit dissapoineted that MXR have not made good use of the first Opamp, rather than just bung it in as a unity gain buffer it could have been put to better use.
It's fairly straight forward, if you want to start it , press start. You can work out the rest of the controls for yourself !

No silicon heaven ? preposterous ! Where would all the calculators go ?
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Re: MXR Custom Badass '78 Distortion

Postby Beto Crazy » 31 Jul 2011, 20:49

I also found, but looking at the circuit now, I see that it is basically the structure of a DS1, of course with modifications.

:applause:

Looking at just the images, it is difficult to make the circuit layout. My layout "was almost" like yours. :mrgreen:

One more time: Thanks man!!!

I never imagined that U2 and U3 were diodes, connections were strangers. The impression he gave me were to be switches, but for U2, this function did not fit.
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