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Subject: Re: Waveforms around the M5232 chip

From: "mark_r_abcd" <mark@...>
Date: 2006-06-21

--- In korgpolyex@yahoogroups.com, Marcus Wilson <JB@...> wrote:
>
> when you turn it on do you get a readout on the 7 segment displays?
>
> 11 P
>
> are you able to check that it sends and receives midi?
>
> have you made sure that you have loaded in patches to ensure that
> there is actually a waveform for the tg to create?
>
> have you checked for output at the headphones AND the L-R outputs?
>
> I had a poly that for a long time I thought was a dead TG, but ended
> up being a dead headphone op amp
>

Hi,

I've only just managed to find time to have another go with this
synth. I've loaded the factory settings, but the problem is still
there. The synth behaves perfectly in all respects except sound
output.

What I have found is that when a key is pressed, one of the
envelope inputs to the TG follows an ADSR curve as expected (so
the envelope DAC and S/Hs are working. As the envelope waveform
tracks out the curve, there is a small square wave on the footage
outputs whose amplitude also tracks the envelope as expected.

But, this square wave amplitude rises to, at most, about 0.2Vpk-pk
sat on a DC level of almost +5V. I would have expected these outputs
to be almost rail-to-rail (+-5V). There are other outputs from the
TG, 2 constant footage outputs (pins 1 and 2 IIRC) and a pseudo
random noise output. These outputs are working correctly (I think
they aren't used for anything in the Poly 800).

Cheers

mark-r