**Gristleizer Build Report!!!** Sound clips for normal people inside!

[jacobyjd]

I think you've almost got it--if you jumper the two highlighted pins together, you should have it Don't hold me to it though, because I can't see where exactly all those wires go in the pics

[deathfaces]

nope, no dice.  i think that connection was wrong on the original gaussmarkov pdf and was corrected.  i used the file marked layout on the right side of the gristleizer page.  i thought this was a corrected version from the comments on the blog and the schematic shows a4 and b1 connected as opposed to a4 and b4 . i traced back the wires and everything appears to be connected appropriately, but still no meshed effect.

this layout:
http://gaussmarkov.net/layouts/gristle/gristle-perf.png

Have you got a closeup of your switch?

[thedefog]

Hey Guys,

I just finished my build tonight, but no dice. I checked my soldering, components, and switch wiring according to the PDF and it all looks good. I'm using a 2 pole 6 way switch with two of the positions unused. I get a ticking from the LFO and the signal passes through weakly. When the DPDT is thrown again, I get nothing at all. So the VCA section of it seems to at least pass a signal, but the VCF is no good.

Speed pot is the only thing that seems to affect anything. I'm going to trace the signal path and see where it's stopping.

[thedefog]

Hey Guys,

I just finished my build tonight, but no dice. I checked my soldering, components, and switch wiring according to the PDF and it all looks good. I'm using a 2 pole 6 way switch with two of the positions unused. I get a ticking from the LFO and the signal passes through weakly. When the DPDT is thrown again, I get nothing at all. So the VCA section of it seems to at least pass a signal, but the VCF is no good.

Speed pot is the only thing that seems to affect anything. I'm going to trace the signal path and see where it's stopping.

OK I seriously need to work on my reading skills. A1 & B1 were not jumpered, as shown in the build report, and my FET was not skipping the hole to go to ground. I'm sure that's all that is wrong. Hopefully my FET wasn't fried being wired to the -9vdc.

[jacobyjd]

So I just noticed that A1 and B1 on the main GM project page actually aren't. In the layout files, it's A4 and B1. If I get a chance in the next few days, I'll open mine up and confirm what I've got to settle this

[deathfaces]

So I just noticed that A1 and B1 on the main GM project page actually aren't. In the layout files, it's A4 and B1. If I get a chance in the next few days, I'll open mine up and confirm what I've got to settle this

That'd be awesome. I'm out of town until Sunday night so no rush. Before i go tomorrow i'll get some readings off the IC's if you want to really go crazy while you've got yours open.

@thedefog that extra trace is really messing everyone up. it got me too initially.

[thedefog]

It is A4 & B1, as I got nothing from the square wave selection of the switch until I wired it this way. Now all the switch positions are doing what they are supposed to. The only issue I seem to have is that the Triangle waveform section is MUCH louder than the others. I dunno if that's the way it is supposed to be, as I have my SH-101 plugged into it and not a guitar so I've got an obvious impedence mismatch for the circuit (even though I've got it turned way down).

[thedefog]

I'm gonna post pictures & sound clips on this shortly. Thanks guys for all of your help!

[jacobyjd]

Interesting--my triangle position is quieter--it never reaches the top of the waveform--it's nothing that I haven't been able to overcome in a live situation

[deathfaces]

Here's what I'm getting. This is with a standard ibanez 9volt supply (same as boss) and GGG bipolar charge pump. I'll probably send a gift to whoever helps me crack this case

IC1
1: -8.43
2: 0
3: 0
4: -8.44
5: -8.43
6: -1.58
7: 8.7
8: 0
IC2
1: -8.44
2: 0
3: -2.45
4: -8.44
5: -8.44
6: -6.3
7: 8.69
8: 0
IC3
1: -8.43
2: 0
3: 0
4: -8.44
5: -8.43
6: -1.69
7: 0
8: 0
IC4
1: -8.43
2: -0
3: -0
4: -8.44
5: -8.43
6: -.05
7: 8.69
8: 0
IC5
1: -8.43
2: 0
3: 0
4: -8.44
5: -8.43
6: .08
7: 8.69
8: 0

D1
Anode: -6.31
Cathode: .01
D2
Anode: .63
Cathode: 1.12

TR1
c: .46
b: -.18
e: .39
TR2
d: 0
g: .63
s: 0

[deathfaces]

it also occurs to me that i originally had the -9v and +9v reversed. could this have screwed something up? everything seems to be reading voltages (although, i have no idea if correct). That last tranny seems suspicious though

IC3 also seems suspicious with 0 at pin 7, which should be v+

lm741 pinout:


Also, I'll create a new post for this if you'd like, i dont want to hijack your thread, though if we get this worked out, it'll be good for the next guy to have it all in one place.

[jacobyjd]

I agree--it's good to have a debug attached to this thread--feel free to keep it going here.

Re: mixing up +/-9v...eh...I don't know enough about all this craziness to tell you for sure that this is the reason your circuit is borked...if you still hear the LFO ticking, then you might be ok, but AFAIK, reverse voltage isn't a good problem to have.

The thing that jumped out at me on those voltages (besides the transistors being wacked out) is that there should be some sort of reference voltage going to the opamp--your voltages look consistent, and I'm guessing vref all goes to the same place. Check that first.

[deathfaces]

I agree, it appears that something is happening, so its not a total failure. The transistors do seem weird. I agree about reverse voltage, i goofed when i was modifying the pcb, but only fired it up for a few moments before i realized i goofed (though i do realize this is more than enough time to fry every ic - which i have extra of, should it come to replacing everything)

noob question. reference voltage means the voltage coming from the adapter i'm using the to power the circuit? if so, it's putting out 8.85v. I'm afraid i dont know what exactly vref is, and couldnt find a clear answer in the forum.
pin 7 should be the v+ to the opamps, so i'd assume thats the culprit on ic3. but when i probe pin 7 of ic3, i get sound - like a buzz, what i assume is the triangle wave.

here's the pinout of the max1044 (charge pump is just below satan in the pictures):
Max1044
1: 8.71
2: 4.29
3: 0
4: -4.27
5: -8.45
6: 4.24
7: 6.42
8: 8.7

Since yours is pretty much the only functional gristleizer the diy community has to offer, would you cross-reference the voltages? i'm ready to start replacing, but dont want to get panicked and premature.

[jacobyjd]

sorry--I think I was getting vref mixed up with Vbias. I'm a noob at the technical side of opamps too

[deathfaces]

hmm, how do i check vbias? Looks like the next step is tracing the audio path, which i've always been crappy at.

also, i meant i get a buzz out of IC3's output, pin 6, when i used an audio probe.

[jacobyjd]

I'm pretty sure Vb should be +4.5VDC

[deathfaces]

Checked the schematic and i'm not sure at what point to check Vb, suggestion?

I have a gut feeling this has something to do with TR2 because that looks like the point on the schematic that links the guitar signal to the LFO. The original Gwinn file indicates this is supposed to act as an attenuator, but i'm still decoding what exactly that means.

Here's the original RG Keen file: http://www.synthdiy.com/files/2005/gep.pdf

[thedefog]

This may be one of those situations where an audio probe would work better than checking voltages to figure out where and when the signal craps out on you.

I'm debugging mine as well. I finally got to check mine out with a guitar instead of my synth, and it still sounds pretty nasty in a bad way. It's pretty distorted. I suspect I have a wrong resistor value somewhere in there. It's a shame I'm color blind because it makes reading resistors that are already on the board impossible.

[-minus]

Hi all! Just joined diy stompboxes as I am building the Gristleizer too. I have a few problems with the wiring of the rotary pot. One of the positions appears to do nothing at all to the sound.  Just wondering if a consensus has been reached as to the correct diagram of what to be wired where. There appears to be conflicting diagrams about A1 B1, A4 B1 etc. Anyone out there able to clarify this for us wannabe TG freaks?

[thedefog]

Hi all! Just joined diy stompboxes as I am building the Gristleizer too. I have a few problems with the wiring of the rotary pot. One of the positions appears to do nothing at all to the sound.  Just wondering if a consensus has been reached as to the correct diagram of what to be wired where. There appears to be conflicting diagrams about A1 B1, A4 B1 etc. Anyone out there able to clarify this for us wannabe TG freaks?

Hey there, and welcome to the forum!

A4 to B1 solved that issue for me. The square wave function won't work (last position on the rotary) if this jumper connection isn't made. Good luck!