SOLVED Malachite (Revv G2) SOLVED

[Bravin Neff]

I just built one, and I'm not getting audio output. Any update on when the schematic will be released? Thanks.

 

[music6000]

I built the Sanguine & they are the Voltages on that.
Funny, I live in Australia with 240v & 110v in USA gives Power Supply more juice if that's where you are.
Here's my Build :

Sanguine Distortion

Cool Distortion Pedal! 3 Band EQ lets you dial in Your sound. 3 types of Distortion via Toggle switch.

forum.pedalpcb.com

 

[Bravin Neff]

Wow, gorgeous build. Awesome on the graphics, that's really something. Yes, I'm in the US.

Thanks to your help, I was able to (just now) trace the circuit backwards, and where the audio stops in pin 2 of the Mid tone pot. After that is R16, which also has no audio, which then feeds pin 5 of the the TL072 that is showing the wrong voltage on pin 5. So I believe something is wrong with my B100K mid pot, or maybe pin 2 is shorting to ground or something? Or maybe that TL072 has a pin shorting to ground or something?

Will investigate further.

 

[music6000]

Try Continuity Test from Mid 2 Lug to R16, Maybe trace is damaged. It runs across the Top & Down the right side by the image.
Try a Jumper wire if there is no connection.
It's now 12.30 am, so Goodnight & Good Luck.

 

[Bravin Neff]

I isolated it to a damaged/faulty mid tone pot (B100K). I removed it, installed a near substitute that I had about, and the voltages you told me to expect emerged. And the sound makes it to the output now.

I very much appreciate your help!

 

[washburn]

Hi everyone
The schematic link is broken.
Would anyone have the schematic please?

a thank you from Brazil.

 

[Paul.Ruby]

I traced out a schematic. Not verified.

 

[temol]

G2 = G4 except:
C3: 100p to 47p
R13: 33k to 82k
R14: 10k to 22k
C11: 100p to 120p
R18: 150k to 22k
R21: 100k to - not present
C21: 47n to 10n
R29: 10k to 22k
C26: 100p to 47p
R31: 10k to 15k

 

[Paul.Ruby]

G2 = G4 except:
C3: 100p to 47p
R13: 33k to 82k
R14: 10k to 22k
C11: 100p to 120p
R18: 150k to 22k
R21: 100k to - not present
C21: 47n to 10n
R29: 10k to 22k
C26: 100p to 47p
R31: 10k to 15k

That almost jibes with my tracing. Only difference I see is R21 to be 22k instead of removed. Also, the Malachite calls it R17 and it has a value of 56k. We seem to have three possible options... The Malachite is definitely 56k in that spot.

EDIT: From a circuit point of view, removing it doesn't make sense to me. The bass control would not work properly. It removes the source of the bass signal to add to the treble.

 

[temol]

I've just checked Malachite schematic I have - no R21/100K. I've also compared Sanguine and Malachite build docs. There is one resistor missing on the Malachite pcb layout drawing (upper right corner). But.. R21 is present on the Malachite pcb image here. Aaand.. if you take a look at the post #11 on the previous page - there is a picture of the G2 board... and no R21.
So.. tracing/schematic/pcb mistake or no R21 in the G2?

 

[Robert]

The preview on the product page was actually the Sanguine before the Malachite PCB was complete. That needs to be updated.

I'll have to hunt down my pics from the G2, if I recall correctly "R21" was a zero ohm resistor. This always seemed a little fishy to me.

@Paul.Ruby can you confirm for sure that you do have a 22K in that position?

BTW I'll get the Malachite schematic reposted ASAP.

 

[Paul.Ruby]

I ordered the malachite from here... Build doc labels it as R17, lists it's value as 56k. I checked my board to find that the position is definitely correct for the resistor in question, leading to the top of the BASS pot. So... I have 56k installed on my malachite board, but only at the stuffed-board phase of the build.

The 22k value came from tracing this vero board layout:

Revv G2 Pedal

Shares the same footprint as G4 pedal but some component values is tweaked for less gain and slightly different overall eq.

dirtboxlayouts.blogspot.com

A friend of mine has a real G2... I'll see if I can borrow it for a bit...

 

[Paul.Ruby]

If you take a look at the post #11 on the previous page - there is a picture of the G2 board... and no R21.
So.. tracing/schematic/pcb mistake or no R21 in the G2?

I have both boards in hand and stuffed. R17 (56k) of malachite is the same resistor as R21 (100k) of Sanguine. The layout is a little different, but they are definitely both the resistor feeding the top of the bass pot. I just need to borrow my buddies G2 to see what the real deal has...

 

[Paul.Ruby]

Oops. The malachite *does* have zero ohm for that spot. R17 (56k) on malachite is R20 (56k) on Sanguine. The use of 0-ohm fooled me with my continuity tester since it is indeed connected directly to the BASS pot. I was interpreting "removed" for R21 as "infinite" instead of as a wire. So, there is likely no controversy. It's 0-ohm. Just my mis-interpretation of removed.

 

[Paul.Ruby]

Not that it matters now, but here's a corrected schematic...

 

[stevel]

I am really confused - is there something about the Malachite build doc and/or PCB that is incorrect? Is there some resistor that should actually be a 0 ohm instead of what it shows on the build doc / pcb?

 

[Teddeeh]

Any update to this?

 

[Robert]

I am really confused - is there something about the Malachite build doc and/or PCB that is incorrect? Is there some resistor that should actually be a 0 ohm instead of what it shows on the build doc / pcb?

The original pedal used a zero ohm resistor as a jumper, most likely as a last minute modification after the PCBs were manufactured.

The Malachite omits this resistor (and instead just uses a solid trace) because it isn't needed.

The Malachite schematic and PCBs are correct.