Update 9/9/14: The (mostly) complete Soul Food schematic
Well, I couldn’t get a lot of cap values. We can just assume they’re the same as the Klon. After triple checking everything, there might still be an error or two in there, but it should be mostly correct.
Update 9/7/14
I’ll keep the SF stuff in one post, so this is going to be edited as I go.
I whipped up a quick & lazy Soul Food schematic on top of soulsonic’s schematic for the Centaur. It should illustrate the differences. I’ll make a better one with when I have time to sit down and work out the TBP/Buffer switch. There’s a lot of SMD caps stuck in their in parallel with other caps for some reason. Even with film caps that have the original Centaur values. I’ll see what kind of reading I can get on them, if any, and compare their equivalent capacitance in the circuit to a Klone.
Original Post
Uh, it’s supposed to be a Klone clone. A lot of it is. The rest?
1N60Ps for the clipping diodes. But we already knew that.
Well, R15 seems to be missing. I mean there literally isn’t a resistor labeled R15 on the board. After going through every part, the numbering jumps from R14 to R16. I’d expect it to correspond to soulsonic’s R11 and be 15k.
C5 is soulsonic’s C8, and it’s 390nF as expected. But it’s in parallel with a 27nF cap. Both connect to R5 (soulsonic’s R9). which is 680E, not 1k.
The pots are labeled B103, B103, and B104. To double check, I measured them and they’re all linear. This is just like the KTR/soulsonic schem.
The SF uses 5k1 and 12k resistors where the KTR uses 5k11 and 12k1. I was hoping this would be a clue as to whether Mike Matthew’s had traced a Klon or used the Chittum schematic, but the all the other deviations make it hard to tell.
The 422k and 392k resistors are 430k and 330k respectively. These are R16 and R10, corresponding to soulsonic’s R12 and R20.
The ICs are TI TL072Cs and one TC7660SE.
There’s a solder glob on R3. A mark of quality!
The notorious Treble pot resistors are in the proper soulsonic locations, not the Silver Pony spots. They’re R18 and R21, for soulsonic’s R21 and R23.
C10 (same part number on SF and soulsonic schem) is a 68nF film cap, not a 1uf electro. At least it seems to be the corresponding cap.
I can’t find anything that corresponds to soulsonic’s C5 or R6.
C15 is C15, but it’s 1uf, not 4u7. Probably not audible. C24 is soulsonic’s C2, and it’s 4u7 as expected.
Can’t find soulsonic’s R27. There’s only one 68k, and it’s where we’d expect it, and there doesn’t seem to be anything in R27’s place.
EHX did not implement Bill Finnegan’s two 2M resistors to allow for the Almost Always switch and keep the same input impedance. The Buffer/TBP switch looks much simpler than the KTR’s. I’ll give a better look once my head has cleared. I didn’t find a drop down resistor for when it’s in TBP mode.
The two 27k resistors that do their voltage divider thing are 100k’s.
Ok, I’m a bit burnt out. I’ll post some pics and come back to this thing later.
So is the Soul Food really a klone? Well, it’s closer than the Banzai Cold Fusion. But I’d say that any other klone on the market gets closer than the Soul Food.
Thanks for your great work in tracing out this circuit!
I’m doing a soulfood repair right now. i’m thinking the charge pump is bad…could let me know what +V2 and -V are supposed to be?
Thanks!
Off the top of my head, I don’t remember. If you look at some threads on diystompboxes, you might be able to find one where the correct voltages were posted for a klone build. They should be about the same for the SF.
Great schematic. Using it to sleuth out problems on a non-functioning bass soul food (fried -V regulator) which appears to be nearly the same schematic-wise, although from the pics I see it has a totally different pcb layout. One thing I did notice, I believe C17 is incorrectly shown going between -V and +V2. On mine it is between -V and gnd. I believe it is a HF bypass cap for -V on U2 which it is near, at least on the bass SF.
I don’t have the SF on hand to double check, but I did notice something weird going on around C17. I think there was a hidden layer sandwiched between the top and bottom layers of the PCB making some connection that wasn’t there in the real Klon circuit. Maybe they made it more like the real thing in the bass version.