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Can anyone help me with info for modding my 606?
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Can anyone help me with info for modding my 606?

by willman85 on Fri Nov 19, 2010 8:31 pm

Right, I know sod-all about electronics but I want to mod my tr-606 to get a deeper 808-like bassdrum with controls for pitch and decay, according to the geoff waterston mod: http://machines.hyperreal.org/manufactu ... emix1.html

I think I am ok for the resistors and potentiometers but I am clueless on the capacitors. I am based in the uk, and a look on the maplin website shows over a dozen different types of capacitor - and none of them are at the 82nf that I require! Also none of them really match in appearance to the capacitors I've seen in pictures of the pcb (at c19 and c20).

So ... what type do I get? And where from? Will I still be able to get ones in the 82nf variety?
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Re: Can anyone help me with info for modding my 606?

by chatham on Fri Nov 19, 2010 10:37 pm

So, you're right, it looks like Maplin may not have the proper caps. On the one hand, electronics is all about experimentation, and is more akin to cooking than baking - exact values are nice, but a lot of times, you can get away without them. Figure, common components have tolerances of +- %5 to +- %20. On the other hand, realistically, resistor and capacitor production technology is such that tolerances in real life are generally pretty tight, and with this particular circuit, the values of the caps are what's determining the waveform that's being generated.

So, we'll take the middle ground - Capacitors, in parallel, act like resistors in series - the total capacitance of parallel capacitors is equal to the sum of all the capacitors. So, I did see on the Maplin site that you can get some 0.033uF and .047uF capacitors - so you can use one of each in place of each .082uF capacitors and probably get close enough at 0.080uF. Part of the reason that there are .082uF caps in the schematic is that that's just the next biggest size up from .068uF. In terms of type of capacitor, the ceramic disc or resin coated ones should be fine. Resistors and capacitors are troublesome for the beginner, since there's a lot of options out there, but usually, they don't really matter. You probably don't have any serious currents in this circuit, so...

Otherwise, you could always try some other mail-order store to get the exact value caps, but the shipping cost is going to not make sense for less than $1 worth of parts...
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Re: Can anyone help me with info for modding my 606?

by stinkbutt on Fri Nov 19, 2010 11:04 pm

willman85 wrote:So ... what type do I get? And where from? Will I still be able to get ones in the 82nf variety?


Four 20 nf caps in parallel get you damn close to 82 nf.

[EDIT]
Oh. 33+47 is even better. Do that instead.
[/EDIT]
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Re: Can anyone help me with info for modding my 606?

by willman85 on Sat Nov 20, 2010 2:44 pm

Thanks! Things are a lot clearer now. Fingers crossed I don't mess the job up!
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