Rather than bump up the previous thread on the Gonkulator (which didn't even have "Gonkulator" in the subject - I almost didn't bother to read it), I thought I'd try to keep the fire burning on this one with some much better, much higher resolution pics...
Component side (http://www.moosapotamus.com/Gonkulator2.gif)
Solder side[/b] (http://www.moosapotamus.com/Gonkulator3.gif)
Yes, it does look like a lot of work to trace. But, to make it even tougher, I don't think it's a single-sided PCB. I think there is another layer of traces that is hidden. For example, look at the pic of the solder side and you'll see three pads in the lower left corner that have no traces connected to them.
Flip to the pic of the component side and you'll see the components in question in the upper left corner... two glass bodied diodes and a small dark yellow capacitor, next to the three pads for upper most pot, the "suck" pot.
I can't see any associated traces with these pads. Even if I hold the board up to a light bulb, I can't seem to see any "shadow" traces. But, using the continuity tester in my DMM, I've confirmed that those three pads are all connected to each other as well as to lugs 1 and 2 of the "suck" pot.
If you look around on the pic of the solder side, you'll find a few more of these seemingly unconnected pads. I've tried hunting around with the continuity tester to try to find connections for some of them, but have been unsuccessful, so far.
I don't have time to dive head first into this one at the moment. Making a clone would be kind of anti-climactic for me since I already have the pedal. And, I've got a bunch of other stuff already in the works that I'd like to finish up.
But, I know there are some folks out there who are interested in this one. So, I hope the pics are helpful. I'd be glad to try to answer any questions about it that I can, too.
~ Charlie
Wellllllllllll,
that's a ground plane on top. 4sure.
usually pcb have even #of layers.
i really doubt Gonkpeople forked out the $$ 4 a 4layer pcb.
Follow all the pos and neg voltaged first.
U know where thry go on the opamps, 1496, etc.
Do the known stuff first, then fill in the blanks.
What R the values and labels 4 the pots?
What does the LED do?
What's the whete connector go to?
inquiring minds etc etc....
tone
Just in passing, in another thread on PCB layout recently, I mentioned "target" crosshair & circle PCB patterns around connections to groundplanes. If you look at some of the caps connecting to the groundplane (component side) you can see this.
I'm voting for double sided too, but anything is possible! Does the Gromnk have much bleedthrough of the local oscillator?
You guys are good! Yeah, most of those pads that look unconnected from the solder side are connected to that ground plane on top. But, some of the pins on the ICs are simply NC. So yeah, definately double-sided.
My Gonk is very quiet, very little osc bleed.
Controls:
Suck = distortion output level
Smear = ring mod output level
Gunk = distortion gain
Heave = overall output level
(http://www.moosapotamus.com/GonkCase.gif)
~ Charlie
Thanks Charlie and Paul!
Well, here's what I can see of the circuit board layout:
http://users.rio.com/senorris/junk/Gonkstart.gif
There are some connections on the top of the board I can't see. Plus, I'm lost up by the pots and down by the switch.
Maybe tonight I can start playing with a schematic unless someone else wants to go at it.
Quote from: Dan N
Well, here's what I can see of the circuit board layout:
http://users.rio.com/senorris/junk/Gonkstart.gif
Man, your layouts are gorgeous, what do you use?
-Colin
Thanks Colin. I use Photoshop. On my computer I can paste the traces down onto the parts and when I hit a pad or trace with the magic wand it outlines the entire trace. I love Photoshop!
Dan
Quote"target" crosshair & circle PCB patterns around connections to groundplanes.
"thermal relief" connections to allow some movement of the pad without disturbing the PCB plane.
I used them on my bassballs build anywhere I needed to connect to the ground plane.
I'm betting you'll find that all of the unconnected pads have continuity between them. Ground plane for sure!
Quote from: Dan N
Well, here's what I can see of the circuit board layout:
For that other mystery IC, here's a pinout:
(http://courses.ece.uiuc.edu/ece343/images/po4007.gif)
Quote from: niftydogI'm betting you'll find that all of the unconnected pads have continuity between them. Ground plane for sure!
Yeah, definately a ground plane. But, not all of the 'unconnected' pads have continuity (within the ground plane). Some of the IC's have pins that are really not connected to anything.
Quote from: Dan NThere are some connections on the top of the board I can't see. Plus, I'm lost up by the pots and down by the switch.
I'll try to fill in some of the blanks when I get a chance.
~ Charlie
Quote from: Dan NThere are some connections on the top of the board I can't see. Plus, I'm lost up by the pots and down by the switch.
I think I've got most of the blanks filled in...
Gonk Rough Layout (http://www.moosapotamus.com/Gonkstart2.GIF)
Let me know if anything looks questionable. Turns out that there are some surface traces within the ground plane that I have shown as traces crossing over each other. And, there are a couple of caps that look like the the other 47n ones (473), but have no markings on them (that I can see, anyway). All the diodes look like 1n914.
So... who's working on a scheme? :mrgreen:
~ Charlie
Wow, you’re a man on a mission!
Spotted something.
In the epicentre of C12, Q5 and Q6 there seems to also be a link between 4k7 and 100k.
You could de solder one side of the mystery caps by applying heat on the track side and gently prying that side of the component up with a small jeweller’s screw driver. To get it back in you can clean the excess solder off the component with a clean solder tip. The hole can be cleaned by applying heat on one side then using a solder sucker on the other side. That’s if you want to be sure about the values.
Also the 47n cap behind Q5 looks kind of large for that value, but then it could be a different type.
Good luck.
Boy Charlie, your additions were a great help! Here is signal into and out of the 1496 (as far as I can see):
http://users.rio.com/senorris/junk/gonkschstart.gif
I'll keep playing with it tomorrow.
Dan
Lookin' good, Dan! 8)
I'll take a look at Rob's comments next chance, too.
~ Charlie
Looks cool. What software do you use to draw the schematic?
QuoteIn the epicentre of C12, Q5 and Q6 there seems to also be a link between 4k7 and 100k.
Good eye, Rob. I caught quite a few more surface traces myself, and added them to rough layout...
Gonk Rough Layout (http://www.moosapotamus.com/Gonkstart2.GIF)
Here's a cool see-through pic that let's them surface traces stand out...
Gonk Board See-Through (http://www.moosapotamus.com/Gonkulator4.gif)
~ Charlie
Wow! That x-ray shot is cool!
Here's my best shot at a schematic. I sh*t canned the flip flops. Some of the Vb points may be bias for fets that are gone? I'm just don't know.
I wonder what the sound would be tapped straight from the center lug of the "smear" pot.
Anyway...
http://users.rio.com/senorris/junk/gonkschemaybe%3f.gif
Marcos, no real program, just cutting and pasteing and old DOD delay schematic.
Cool. I asked this because I saw the same kind of graphics in DOD and other schematics, and I think it was be cool if some software can generate these graphics. Thanks for the schematic, and the x-ray pic is really cool.
Great job on the reverse engineering. Now who will be the first to make a build of it? :D
Take care,
-Peter
Nice work, Dan!
Quote from: Dan NI wonder what the sound would be tapped straight from the center lug of the "smear" pot.
Yup. Or, maybe get rid of the clipping diodes for a basic 'clean blend' control.
How about a varaible frequency control? Anyone see where that could be added?
~ Charlie
I'm guessing U3A and U3B are the oscillator, though pin 6 and the 15pF cap look weird. The back to back diodes connecting the oscillator to the 1496 may be some rudimentary sine shapers.
And U4B is the distortion section for the "dry" signal. Jumper the 10k resistor in the feedback loop, and it'll go from clean unity gain to distorted.
Good eye, Tim. Pin 6 was messed up. Here's another rip:
http://users.rio.com/senorris/junk/gonkschemaybeV2.gif
Charlie, maybe making the 100K resistor on pin 3 of U3/A variable would give you a frequency control.
Thanks for the suggestion, Paul. I tried sticking another 100K across that one, but it didn't really do anything. After a little poking around, it seems the resistor that needs to be made variable (for a variable carrier frequency control) is the 33K that goes between pin 2 (U3a) and pin 7 (U3b). I tried replacing that 33k with a 100K pot and it works quite nicely, seems to cover at least three or four ocataves.
I might consider modding it so that the Heave (volume) pot controls the carrier frequency and just leave the overall output volume fixed. The Suck and Smear pots control the disto and ring mod output levels individually. So, the Heave pot seems kind of unnecessary, anyway.
Noticing something else in the schematic (thanks again, Dan!)...
Check out the section of circuitry that connects pin 1 to pins 8 and 10 of the 1496. This looks like the carrier signal is not going into the 1496 (carrier inputs) by itself. It's getting blended with the clean signal first. When you play through the pedal with the Suck and Gunk controls at zero, it doesn't sound quite like a true ring mod because some of the straight signal is still recognizable in the output. It doesn't sound like a pure ring mod sound.
So, what about breaking the connection at pin 8? Might that result in more pure ring mod sound? Could all those components between pin 1 and pin 8 be taken out, or bypassed? Or, what about disconnecting the carrier input at that point so that the clean signal goes into the carrier inputs and the signal inputs? Would this result in an octave-up sound, or maybe octave-up fuzz like the ringstinger does? What do you guys think?
~ Charlie
Thanks for finding the right freq resistor Charlie! how lame is a ring modulator without a freq control :shock: as for putting a mix of original and oscillator in, the effect of the original signal going in the modulator input is to give frequency doubling (on single notes) and a more complex mix (like a chord thru a fuzz) on chords.
Quote from: Paul Perry (Frostwave)how lame is a ring modulator without a freq control :shock:
totally... like a mustard without a ham. :lol:
Hmmm... So then, do you think might it be interesting to try removing either the original signal or the carrier signal from the carrier inputs?
I know it would be fun to add an input for an external carrier (that I could plug my photo-theremin into :twisted: ).
Thing is, I'm not sure I really want to go and start cutting up traces on my Gonk. So, I may have to think about making one after all. :shock:
~ Charlie