Roland DD6 effects pedal

[N_Cook]

I'm probably wasting my time on this one but if anyone has some insight
I will sold(i)er on.

ucontroller responds to function changes correctly but audio output stays at
bypass. That u sends data that varies on function change to pin 63 of a Boss
proprietary 80 pinner. AK5353VT ADC sends data to pin 68. There is data flow
to the RAM but otherwise nothing comes out. The AK4352VT DAC is ready to
receive but nothing there. This main Boss chip runs warmer than should and
more than the 55mA consumption , in specs .

 

[N_Cook]

N_Cook <diverse@tcp.co.uk> wrote in message
news:gtcf8d$rsf$1@news.eternal-september.org...

I'm probably wasting my time on this one but if anyone has some insight
I will sold(i)er on.

ucontroller responds to function changes correctly but audio output stays
at
bypass. That u sends data that varies on function change to pin 63 of a
Boss
proprietary 80 pinner. AK5353VT ADC sends data to pin 68. There is data
flow
to the RAM but otherwise nothing comes out. The AK4352VT DAC is ready to
receive but nothing there. This main Boss chip runs warmer than should and
more than the 55mA consumption , in specs .

Would you adam and eve it? I seem to have made a peak limited (grey?) white
noise generator.
I wanted to see if the DAC was still working as there is 5V on the supply
and the datasheet recommends 3.6V and absolute maximum of 4.6V. I cut
data-in line, pin 4, of AK4352VT, from the main Boss chip and connected ,
via 1K, to pin 9 , data out, of the ADC AV5353VT.
Maximum allowed on the ADC is 6V supply and of course absolutely no
technical data of any sort on the www for the DD6 so anything I can
establish is new territory.

Feeding sine in, the ADC o/p datastream varies on frequency. No data into
the DAC then nothing out. Connect datastream and there is 2V peak limited
white noise on the analogue output. Varying sine input or even disconnecting
makes no observable difference to the noise output. Scope shows no obvious
periodicity 100Hz to 100KHz, and sounds like white noise. Other select lines
are still connected but what , in principal, is occuring ? Presumably the
DAC is still working, both channel o/ps have this "white" noise.

--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Bob Larter]

N_Cook wrote:

Would you adam and eve it? I seem to have made a peak limited (grey?) white
noise generator.
I wanted to see if the DAC was still working as there is 5V on the supply
and the datasheet recommends 3.6V and absolute maximum of 4.6V. I cut
data-in line, pin 4, of AK4352VT, from the main Boss chip and connected ,
via 1K, to pin 9 , data out, of the ADC AV5353VT.
Maximum allowed on the ADC is 6V supply and of course absolutely no
technical data of any sort on the www for the DD6 so anything I can
establish is new territory.

Feeding sine in, the ADC o/p datastream varies on frequency. No data into
the DAC then nothing out. Connect datastream and there is 2V peak limited
white noise on the analogue output. Varying sine input or even disconnecting
makes no observable difference to the noise output. Scope shows no obvious
periodicity 100Hz to 100KHz, and sounds like white noise. Other select lines
are still connected but what , in principal, is occuring ? Presumably the
DAC is still working, both channel o/ps have this "white" noise.

Sounds like something's wrong on the input side of the ADC. Have you
tried using a scope to follow a signal from the input socket to the ADC?

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

 

[N_Cook]

Bob Larter <bobbylarter@gmail.com> wrote in message
news:gtgdov$lhq$1@blackhelicopter.databasix.com...

N_Cook wrote:
Would you adam and eve it? I seem to have made a peak limited (grey?)
white
noise generator.
I wanted to see if the DAC was still working as there is 5V on the
supply
and the datasheet recommends 3.6V and absolute maximum of 4.6V. I cut
data-in line, pin 4, of AK4352VT, from the main Boss chip and connected
,
via 1K, to pin 9 , data out, of the ADC AV5353VT.
Maximum allowed on the ADC is 6V supply and of course absolutely no
technical data of any sort on the www for the DD6 so anything I can
establish is new territory.

Feeding sine in, the ADC o/p datastream varies on frequency. No data
into
the DAC then nothing out. Connect datastream and there is 2V peak
limited
white noise on the analogue output. Varying sine input or even
disconnecting
makes no observable difference to the noise output. Scope shows no
obvious
periodicity 100Hz to 100KHz, and sounds like white noise. Other select
lines
are still connected but what , in principal, is occuring ? Presumably
the
DAC is still working, both channel o/ps have this "white" noise.

Sounds like something's wrong on the input side of the ADC. Have you
tried using a scope to follow a signal from the input socket to the ADC?

--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

I did introduce the sine at the 1/4 inch inputs , and op-amps between but
scoping the ADC inputs , they are fine. Curiously my first job in
electronics was constructing a psedo-random sequence generator, filtered
down, to produce peak limited "white noise". For RF transmission line
testing , so requiring MECL logic , rather than for audio. No longer have
access to a spectrum analyser, but would like pass it through one.
There are (scope measured) 50K, 400K, 11M clock and other pulse trains and
not determined whether they are as should be , at the moment just an
interesting curiosity. It is stable , invariant to ps voltage change from
4.3V to 5V.
Not grey noise or any other "coloured" noises that I can find reference to.
The pk to pk maximum is 1/2 the power rail voltage of 5V, so no nasty short
duration peaky spikes of real noise that cause their own problems over
transmission lines IIRC.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Bob Larter]

N_Cook wrote:

Bob Larter <bobbylarter@gmail.com> wrote in message
[...]
Sounds like something's wrong on the input side of the ADC. Have you
tried using a scope to follow a signal from the input socket to the ADC?

I did introduce the sine at the 1/4 inch inputs , and op-amps between but
scoping the ADC inputs , they are fine.

Are you still seeing the sine wave at a pin on the ADC?
I ask because the symptoms you describe sound like something in the ADC
input chain is losing the signal & supplying noise instead.

Curiously my first job in
electronics was constructing a psedo-random sequence generator, filtered
down, to produce peak limited "white noise". For RF transmission line
testing , so requiring MECL logic , rather than for audio. No longer have
access to a spectrum analyser, but would like pass it through one.

I doubt that that would help you. I think that a scope is all you need,
based on the symptoms you're describing.

There are (scope measured) 50K, 400K, 11M clock and other pulse trains and
not determined whether they are as should be , at the moment just an
interesting curiosity. It is stable , invariant to ps voltage change from
4.3V to 5V.

Do you have any data on the correct Vcc for the chips?

Not grey noise or any other "coloured" noises that I can find reference to.
The pk to pk maximum is 1/2 the power rail voltage of 5V, so no nasty short
duration peaky spikes of real noise that cause their own problems over
transmission lines IIRC.

Maybe I'm wrong, but it really looks to me like you're getting noise at
the ADC input, & your tweak is merely coupling it to the output.


--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

 

[N_Cook]

Bob Larter <bobbylarter@gmail.com> wrote in message
news:gthedb$4rr$1@blackhelicopter.databasix.com...

N_Cook wrote:
Bob Larter <bobbylarter@gmail.com> wrote in message
[...]
Sounds like something's wrong on the input side of the ADC. Have you
tried using a scope to follow a signal from the input socket to the
ADC?

I did introduce the sine at the 1/4 inch inputs , and op-amps between
but
scoping the ADC inputs , they are fine.

Are you still seeing the sine wave at a pin on the ADC?
I ask because the symptoms you describe sound like something in the ADC
input chain is losing the signal & supplying noise instead.


Curiously my first job in
electronics was constructing a psedo-random sequence generator, filtered
down, to produce peak limited "white noise". For RF transmission line
testing , so requiring MECL logic , rather than for audio. No longer
have
access to a spectrum analyser, but would like pass it through one.

I doubt that that would help you. I think that a scope is all you need,
based on the symptoms you're describing.

There are (scope measured) 50K, 400K, 11M clock and other pulse trains
and
not determined whether they are as should be , at the moment just an
interesting curiosity. It is stable , invariant to ps voltage change
from
4.3V to 5V.

Do you have any data on the correct Vcc for the chips?

Not grey noise or any other "coloured" noises that I can find reference
to.
The pk to pk maximum is 1/2 the power rail voltage of 5V, so no nasty
short
duration peaky spikes of real noise that cause their own problems over
transmission lines IIRC.

Maybe I'm wrong, but it really looks to me like you're getting noise at
the ADC input, & your tweak is merely coupling it to the output.


--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------

The serendipitous noise generator works whether there is a signal or not at
the input of the ADC. I just started out feeding a sine in. The supply to
the DAC may just be wrong. I've no info from Boss but except for the opamps
the main chippery has a regulated 5V including the ADC and DAC. According to
the datasheets this is fine for the ADC but recommended 2V to 3.6V for the
DAC and maker's maximum stated as 4.6V for the DAC. I cannot find info on
the regulator but it functions properly giving 5V but of course it maybe
wrong and jumped from 3.5V to 5V but my hunch is 5V is the intended voltage
and some variant of DAC used by Boss.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Bob Larter]

N_Cook wrote:
[...]

The serendipitous noise generator works whether there is a signal or not at
the input of the ADC.

That's why I think something's gone bad on the input side of the ADC.
Scoping out the input signal path should identify your noise source.

I just started out feeding a sine in. The supply to
the DAC may just be wrong. I've no info from Boss but except for the opamps
the main chippery has a regulated 5V including the ADC and DAC. According to
the datasheets this is fine for the ADC but recommended 2V to 3.6V for the
DAC and maker's maximum stated as 4.6V for the DAC. I cannot find info on
the regulator but it functions properly giving 5V but of course it maybe
wrong and jumped from 3.5V to 5V but my hunch is 5V is the intended voltage
and some variant of DAC used by Boss.

That sounds reasonable.



--
W
. | ,. w , "Some people are alive only because
\|/ \|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------