[sdiy] MN3007 Chorus Acting Weird

[Jacob Watters]

I am testing it with a sine wave from a signal generator. When I look at a
scope, I only see vertical movement. When I listen with my ears, I only
hear panning.

I found this photo of the service manual. It's difficult to read the exact
values, but maybe someone familiar with the IC will be able to tell how it
should be functioning. The BBD part is in the rectangle at the bottom with
the "DC 1/2" label.

https://rvb-img.reverb.com/image/upload/s--wzg-Dhdj--/f_auto,t_supersize/v1669410662/zuo0v17w68dkc6c0n99s.jpg

*Jacob Watters*
JacobWatters.com <http://jacobwatters.com/>


On Sat, Feb 15, 2025 at 4:28 PM Richie Burnett <rburnett at richieburnett.co.uk>
wrote:

> What input signal are you testing it with?
>
> -Richie,
>
>
> -----Original Message-----
> From: Jacob Watters via Synth-diy
> Sent: Saturday, February 15, 2025 9:17 PM
> To: SDIY
> Subject: [sdiy] MN3007 Chorus Acting Weird
>
>
> I am repairing a Yamaha KM602 mixer, which has a builtin MN3007 circuit.
> The
> chorus circuit behaves a bit odd. Instead of being a modulated delay that
> causes a pitch shift, it seems to behave like an auto-pan circuit. The
> sound
> level increases on one side, while decreasing on the other, and alternates
> back and forth. It is labelled as CHORUS on the front panel, so that is
> not
> the behavior that I expected.
>
> Is this normal, or is something wrong with the circuit?
>
> I tried finding a pdf of the service manual online, but I was
> unsuccessful.
> Does anyone have the service manual and can provide some input as to how
> the
> circuit should work?
>
>
> Thanks for your help!
>
> Best regards,
>
> Jacob Watters
> JacobWatters.com
>
>
>
>
>
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