There was a trimmer resistor replaced. I saw your advice in another thread and tried this, but it seemed the resistor had no real effect on scaling. I hooked up a meter to it and just set it at 1k2 which seemed like a suggested resistance. If I get the oscillators high tuning tuned at C when playing C6, when I play C2 there is no way for me to get it in tune to C (not even close) with just VR1, 2, and 3 (especially considering VR2 doesn't do anything).
On Mar 31, 2012, at 8:46 AM, backshall1 wrote:
> When using a trimmer resistor (I assume it replaces R93) with a new
> opto-coupler, it is best to set all other VRs (VR1,2,3) to mid-point, set
> the trimmer where you get the best scaling, and start from there. VR4 and 5
> are not associated with tuning.
>
> Also, try adjusting VR14, marked D#4-E4. This adjusts the scaling for the
> upper end of the keyboard.
>
> Don B.
>
> _____
>
> From: PolySix@yahoogroups.com [mailto:PolySix@yahoogroups.com] On Behalf Of
> genetik
> Sent: Friday, March 30, 2012 9:53 PM
> To: PolySix@yahoogroups.com
> Subject: [PolySix] Tuning Issue--the opto is replaced
>
> Hi, I just picked up a polysix with the battery replaced and board cleaned
> up. Everything is functional. The only issue is tuning. I followed the
> service manual and cannot get the synth in tune. It seems like the range of
> the VRs for the oscillators. If the high note C is in tune, the VR maxed out
> is still not C. And visa versa. After tuning high C at C6 with 4', C2 cannot
> be set to 0 cents either. It is more like A or A#. The scaling seems off.
> The opto is replaced with a VTL5C3 that tests correctly and has a
> fine-tuning resistor that i set at 1k2. Only that that seems weird is that
> when I put the test lead of my multimeter of pin 6 of the connector for
> keyboard tracking it shows -5V. VR5 and VR2 seem to do nothing. Help!
>
> [Non-text portions of this message have been removed]
>
>
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