<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto"><div>I never found a schematic. But the circuit is not hard to trace.</div><div>The ic is a 4017, producing 6-8 step sequences. The kick drum and other drum circuits are very typical twin t circuits. The snare is just a tom tom sound, no white noise of its own. The hi-hat/shaker sound uses a coil like the Boss DR-55 to produce that whistling blue noise. In my experience with 2 of these machines there is a wide range of deviations between components and sound quality, and the trim pots are not enough to get things sounding nice. It’s a toy basically and the kick drum has no kick. I designed a pcb with some of the Monotribe drum voices and room for a Xiao type microcontroller to fit in the enclosure but I have not gotten around to trying it out. This is because the new circuits would require a better power supply than a 9v battery and it just seemed like too much love for such a low quality toy. </div><div>But winter is coming so I may need a small project like this to keep me busy. (In particular the Monotribe kick drum sound and snare would help the CRM-260. I have a mod to extend decay on the kick and add swept pitch but it’s a half sine wave sound that is quite nasty.)</div><br id="lineBreakAtBeginningOfSignature"><div dir="ltr">Benjamin Tremblay</div><div dir="ltr"><br><blockquote type="cite">On Nov 24, 2025, at 6:02 AM, David Huss via Synth-diy <synth-diy@synth-diy.org> wrote:<br><br></blockquote></div><blockquote type="cite"><div dir="ltr">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<p>Hi,<br>
<br>
I have a AK Drummer (CRM-260) Rhythm Machine and I am looking for
a schematic. </p>
<p>I searched the web high and low. I figured out that this was also
sold under the names Conrad CRM‑260 or CORT CRM-260 in what seems
to be identical devices (apart from the different manufacturer
logo). </p>
<p>I found <a moz-do-not-send="true" href="https://www.youtube.com/watch?v=9z71-mFVPcs">a 10 year old
youtube video</a> where someone has moded the thing, but there
is no description and in a comment from 5 years ago they say the
documentation has been lost. </p>
<p>Does anyone know a thing?<br>
<br>
All the best,</p>
<p>David/atoav</p>
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