Grind Customs Chimera V 3 questions...

[Bendeane]

I stumbled across an almost completed Chimera as part of a lot I found on Ebay.  After a little tweaking and fixing of a few things the original builder did, I've got it up and running with a few little quirks I wanted to get some feedback on.

The Volume and Treble pots seem to have an affect on the signal when the circuit is bypassed.  Is this normal for Klons and Klon type circuits? 

The Gain pot is working backwards (at zero its full gain and 10 its no gain).  Trouble is, when I flip the lugs around in every conceivable combination I can think of, I either get a Gain pot that sounds as it should only backwards or a Gain pot with very very little gain, but that seems to be "working" in the right direction (there is zero gain at zero, but when I crank it to 10 I hear an increase in gain, but it is incredibly light).  With the pot sounding like it should, only backwards, the sound of this thing is incredible!  I just want it to work right in case I decide to sell it later on.

Thanks for any advice.

[jimilee]

No, it shouldn't have an effect in bypass, did you use buffer bypass or true bypass. The gain pot, it's a dual gang pot, right? Also, check your parts against the schematic not the bom or check the bom against the schematic, Rej used to sometimes inadvertently swap values. Next, take voltages and post pictures.


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[Bendeane]

Thanks!  It is the buffered V3.  Yes to the dual gang pot.  Biggest trouble is, I got the thing in a lot with some other pedals that I've since fixed, but this one lay gathering dust til now.  Don't know why I waited, but no I can't seem to find any build docs, schematics, etc.  All the links floating around now are dead ends.

Double checked as I was typing this, and yes, all three pots have an affect on the signal in bypass.  Different though than when it's running thru the circuit.  Maybe I'll post a video if I'm ambitious enough...so many other ideas for builds running around in my tiny brain!

[jimilee]

I'll look to see what docs I have, hopefully some other folks will chime in, maybe change the title to also need build docs. Folks are pretty helpful.


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[zombie_rock123]

I think this is the V3, it's the one I found on my phone. Apologies if it's not the one that's been asked for, is the Grind website down?

[jimilee]

Yup


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[Bendeane]

I think this is the V3, it's the one I found on my phone. Apologies if it's not the one that's been asked for, is the Grind website down?

Thanks so much!  That's the one. I'll start comparing parts. The board was populated when I bought it. There are enough quirky things going on with the build when I started to mess with that that lord knows what parts may be different from what is called for in the BOM. All the electrolytics are bi polar, one of the chips was soldered in upside down and the switch was wired turned  90 degrees. They used a 3pdt, but that's probably just what he or she had on hand and isn't that unusual. With this build doc I should have it all figured out tonight or tomorrow. I'll send updates but thanks again!!!


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[Bendeane]

I think this is the V3, it's the one I found on my phone. Apologies if it's not the one that's been asked for, is the Grind website down?

Oh, and yes to the grind website being down. Plus all his Dropbox links are broken now too.


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[zombie_rock123]

For a moment I thought you meant the chip had the pins bent backwards and soldered in!

A 3PDT would work if you only used two of the poles. Hopefully something jumps out at you, I'm not sure bipolars would work bit of a strange choice there. Best of luck and definitely post updates.

[Bendeane]

Yeah, I thought the bipolars were odd.  I've seen people just use two of the 3 poles of a 3PDT when it's all they had on hand, but given the oddities in this build, it doesn't appear that the original builder used what he had laying around, but instead ordered particularly for the build.  I could be wrong.

I might change on the electrolytics to polarized where they're called for in the schematic just to see.  The pots affecting the signal when I'm bypassed is more puzzling than anything...

[Bendeane]

First error found...

The 4.7 uf caps in C16 and C3 are 47uf and the 47uf that are supposed to be in C17 and C22 are 4.7uf...I'm still learning a ton, but I suppose C17 and C22 being 10x lower than what the circuit calls for could affect power supply ripple.  I assume C16 and C3 are DC blocking, but I am not sure how having a cap 10% of the value called for would affect things their either.  More to come I'm sure!  Thanks again for all the help...

[zombie_rock123]

Weird choice. Cant help but feel it was a first build for someone who got Klon fever. I woulda thought the switch wiring was iffy if youve got change with the pots in bypass, does the switch wiring check out?

[Bendeane]

Weird choice. Cant help but feel it was a first build for someone who got Klon fever. I woulda thought the switch wiring was iffy if youve got change with the pots in bypass, does the switch wiring check out?

Yeah, the switch checks out. It was flipped 90 degrees when I got it so I fixed that (7,4,1 and 9,6,3 were used but I've got it wired up correctly with 1,2,3 and 7,8,9. Not using the center pole). I'll check for solder bridges on the lugs since those 68k resistors are wired on tightly to the physical switch.


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[Bendeane]

Ok, so some of you might think I'm bonkers, but the pots affecting the signal when the pedal is bypassed is gone now.  I think I may have shorted the drive pot in some way so that when I had the pedal switched in bypass mode, it was still letting the signal thru the circuit.  If I understand correctly, the first pole of the switch not only turns off the LED when bypassed, but also lifts the GE diodes.  This makes some sense because when I was in bypass mode, the Gain pot acted more like a clean boost, which I assume is what it would do if you took the GE diodes out of the circuit entirely. 

[jimilee]

Look up millennium bypass. If I'm not mistaken, the traces on the stomp switch pads trace it out there, he was trying to make it as easy as possible.


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