[sdiy] Looking for: AK Drummer (CRM-260) schematic

[Adam (synthDIY)]

Aah, ok, I missed that, I was wondering why the clock oscillator was fixed, doh...  
I wonder if that's ganged to the other 50K pot in the Cymbal circuit. 
I seem to recall Roland did that with one of their analogue drum machines i.e. adjust the hi hat decay according to the tempo.. which makes eminent sense musically.

A

> On 25 Nov 2025, at 12:56, brianw <brianw at audiobanshee.com> wrote:
> 
> I can't tell what it does without pin numbers for the SN7450. That's a dual AND-OR-INVERT package, so I'm not really sure what they've set it up to do.
> 
> The 50K control in the schematic, lower left, sets the tempo, but the faceplate shows what appears to be a stepped attenuator rather than a potentiometer.
> 
> Brian
> 
> 
> On Nov 24, 2025, at 6:36 PM, Adam wrote:
>> Pure gold.
>> 
>> So... it actually only ever plays at ONE tempo, but you get divisions of that tempo?
>> 
>> A
>> 
>> <grab 2025-11-25 at 12.34.27.png>
>> 
>> 
>> On 25 Nov 2025, at 11:51, Loscha wrote:
>>> Hi David and group
>>> 
>>> I got one of these machines about 12 years ago
>>> And it came with the following documentation.
>>> 
>>> I have a unit somewhere in my garage here in Australia.
>>> It's missing the to half of the lid I think, but has all the circuitry
>>> If it'd help you out, I can try and find it over the weekend and we can arrange postage
>>> 
>>> Pretty sure this schematic will help!
>>> 
>>> //Edward 
>>> 
>>> On Mon, 24 Nov 2025 at 21:56, David Huss via Synth-diy <synth-diy at synth-diy.org> wrote:
>>>> Hi,
>>>> 
>>>> I have a AK Drummer (CRM-260) Rhythm Machine and I am looking for a schematic. 
>>>> 
>>>> 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).  
>>>> 
>>>> I found a 10 year old youtube video 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.  
>>>> 
>>>> Does anyone know a thing?
>>>> 
>>>> All the best,
>>>> 
>>>> David/atoav
>> 
> 
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