<div dir="ltr"><div>Is it a shortcoming of all my 3340 designs, or is PWM supposed to do a DC offset, as well? <br></div><div>So at the smallest duty cycle, I get 0 to +10v, and at the other end, I get 0 to -10v. <br></div><div>At 50% duty is -5v to +5v.</div><div><br></div><div>Sorry to drag this thread out...</div><div><br></div><div>Colin<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Dec 30, 2019 at 1:15 PM klangbau <<a href="mailto:sauterw@web.de">sauterw@web.de</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div bgcolor="#FFFFFF">
<p>I remember a Jürgen Haible hand drawing schematic of a TZ-VCO
based on two 3340 when I was researching about TZ-VCO's<br>
</p>
<p>It is JH3 Dual VCO with TZ option and a CD4077.</p>
<p>Good to have a hard copy to find it again:</p>
<p> <a href="http://jhaible.com/legacy/tonline_stuff/hj2vco.gif" target="_blank">http://jhaible.com/legacy/tonline_stuff/hj2vco.gif</a></p>
<p>willi</p>
<p><br>
</p>
<p><br>
</p>
<pre cols="72">willi sauter
KlangbauKoeln </pre>
<div>Am 30.12.19 um 20:55 schrieb
ColinMuirDorward:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Steve, you could ask Alfa Rpar if they would send
you a 3345 sample.<br>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Mon, Dec 30, 2019 at 10:17
AM S Ridley <<a href="mailto:spridley1@gmail.com" target="_blank">spridley1@gmail.com</a>> wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div><br>
</div>
<div>> I wonder if this is a good place to cast my vote
(again!) for a through-zero 3340? <br>
</div>
<div><br>
</div>
<div>The 3345 should be able to do linear FM through zero.
There were some additional applications for the CEM3345 in
the old CEM Synthsource newsletter, spring/summer 1981,
including adjustable triangle symetry and linear through
zero FM - needs a CD4077, an opamp and a comparator. I've
never managed to get a 3345 to see if it works.</div>
<div><br>
</div>
<div>The Synthesource newsletters are reproduced in Barry
Klein's Electronic ICs databook but I haven't seem them
anywhere else...</div>
<div><br>
</div>
<div>Steve </div>
<div><br>
</div>
<div><br>
</div>
<div> </div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun, 29 Dec 2019 at
01:19, ColinMuirDorward <<a href="mailto:colindorward@gmail.com" target="_blank">colindorward@gmail.com</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div dir="ltr">
<div>Thanks for chiming in, Alex. Interesting to hear of
the possibility of a future revision.<br>
</div>
<div><br>
</div>
<div>I wonder if this is a good place to cast my vote
(again!) for a through-zero 3340?<br>
</div>
<div><br>
</div>
<div>Jay, I think you're right, but on the other hand,
using the chip means I don't need to source tempcos or
matched transistors. <br>
</div>
<div><br>
</div>
<div>Colin<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sat, Dec 28, 2019
at 3:13 PM Jay Schwichtenberg <<a href="mailto:jschwich53@comcast.net" target="_blank">jschwich53@comcast.net</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<p>My personal thought is that for just a VCO I'd go
with a classic design. To me these chips are more
appropriate for something like a stand alone
keyboard or poly synth. Using them as a regular
VCO usually requires you to normalize the output
waveforms bias and level, typically with
additional op-amps. By the time you add that
circuitry you're getting close to the number of
chips you have in a classic VCO and a PCB of about
the same size.<br>
</p>
<p>I was wondering if you add the -5V regulator, set
the PWM to some optimal value and then used an
external PWM circuit off the saw wave whether or
not that would either eliminate or considerably
reduce the problem of PWM/frequency issues?</p>
<p>Jay S.<br>
</p>
<div>On 12/28/2019 2:47 AM, Aa Bb wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">(From ALFA RPAR AS) <br>
Dear Sir's<br>
<br>
We've noticed discussion on DIY forum's
about AS3340 PWM issues.<br>
It looks several opinions exist and some of them
are partly close to reality. We <br>
wanted to provide some information about these
question.<br>
<br>
1.1 First important moment - all 3340
incarnations have influence PWM on <br>
frequency (linear influence and spike at 50%).
They differ in character and level. <br>
For better understanding curve -
Freq.dev./ Pwm level must be build an analyzed.<br>
Example of such curve for AS3340-HYB is
provided in datasheet :<br>
<a href="http://www.alfarzpp.lv/eng/sc/AS3340-HYB.php" target="_blank">http://www.alfarzpp.lv/eng/sc/AS3340-HYB.php</a><br>
<br>
1.2 Main source of such influence - very
fast switching of comparator output (pin 4). But
also<br>
some other minor effect exist. High slew rate
makes problems for internal circuitry (high
current spikes <br>
on different internal nets ) and also, if
layout is made not so good, on negative supply
(pin 3).<br>
Almost identical schematics of these
comparator, for better understanding, is
provided<br>
in AS3340-HYB datasheet:<br>
<a href="http://www.alfarzpp.lv/eng/sc/AS3340-HYB.php" target="_blank">http://www.alfarzpp.lv/eng/sc/AS3340-HYB.php</a><br>
<br>
1.3 Different solutions may be used in
different situations and requirements.<br>
1.3.1 Old builds repair.<br>
In old builds situation is "as is" and
it is almost impossible to change anything. For
such case <br>
we offer - AS3340-HYB - solution witch almost
totaly excludes PWM influence on frequency (in
<br>
comparison with all other 3340 variants !!!).<br>
Main idea - DIP module is based on
AS3345F (QFN) and is pin-to-pin compatible with
3340.<br>
Comparator, similar to the one inside of AS3340
is made on separate transistors/resistors.
Internal <br>
comparator is turned OFF. So, high slew-rate
current spikes in these solution are flowing
through <br>
"external" comparator and it's influence on
AS3340 is minimized.<br>
Certainly, for better immunity, output
current minimization, better to decrease output
current<br>
by increasing load resistor till 51k or more
(depends from application).<br>
So, for such case, - our opinion - use
AS3340-HYB.<br>
<br>
1.3.2 For new designs.<br>
Several variants , moments:<br>
1.3.2.1 If You use PWM - "protect" pin3
from pin 4 - layout, bypass capacitor.<br>
1.3.2.2 Try to decrease slew rate of
comparator output:<br>
- increase load resistor (it will
decrease comparator output current)<br>
- connect pin 5 and pin pin 4 with
MegaOhm resistor and add to pin 4 capacitor.<br>
But linear influence PWM on frequency
still remains. <br>
<br>
1.3.2.3 Use AS3340-HYB - witch it the
best in these moment.<br>
<br>
We just tried to explain "mechanism" of
problem. Other schematic tricks can be used.<br>
<br>
<div> We hope, in some time, new revision of
AS3340A will be available.</div>
<div><br>
</div>
<div>ALFA RPAR AS</div>
<div>Alex Zaslavsky<br>
</div>
<div><a href="mailto:alfa@alfarzpp.lv" target="_blank">alfa@alfarzpp.lv</a></div>
<div><a href="http://www.alfarzpp.lv/eng/sc/application.php" target="_blank">http://www.alfarzpp.lv/eng/sc/application.php</a></div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun, 22 Dec
2019 at 01:17, Doug Terrebonne via Synth-diy
<<a href="mailto:synth-diy@synth-diy.org" target="_blank">synth-diy@synth-diy.org</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div>
<div dir="ltr">Yes, the original rev F
CEM3340s in the JP-6 don't have this
issue.</div>
<div dir="ltr"><br>
</div>
<div dir="ltr">Doug <br>
</div>
<div dir="ltr"><a href="http://synthparts.com" target="_blank">synthparts.com</a><br>
</div>
<div><br>
</div>
</div>
<div id="gmail-m_4658011309461797231gmail-m_-3570176100846851034gmail-m_8449761841727835596gmail-m_8796266394253402177gmail-m_2663333955044226633gmail-m_-8014807944889351604ydp5fb438c1yahoo_quoted_7775195667">
<div>
<div> On Saturday, December 21, 2019,
3:11:12 PM PST, ColinMuirDorward <<a href="mailto:colindorward@gmail.com" target="_blank">colindorward@gmail.com</a>>
wrote: </div>
<div><br>
</div>
<div><br>
</div>
<div>
<div id="gmail-m_4658011309461797231gmail-m_-3570176100846851034gmail-m_8449761841727835596gmail-m_8796266394253402177gmail-m_2663333955044226633gmail-m_-8014807944889351604ydp5fb438c1yiv4177196667">
<div>
<div>Thanks, Doug.
<div>Is it true that this
problem didn't manifest with
the original CEM3340?</div>
<div>Colin</div>
</div>
<br clear="none">
<div id="gmail-m_4658011309461797231gmail-m_-3570176100846851034gmail-m_8449761841727835596gmail-m_8796266394253402177gmail-m_2663333955044226633gmail-m_-8014807944889351604ydp5fb438c1yiv4177196667yqt40030">
<div>
<div dir="ltr">On Sat, Dec 21,
2019, 3:08 PM Doug
Terrebonne, <<a shape="rect" href="mailto:dougt55@yahoo.com" rel="nofollow" target="_blank">dougt55@yahoo.com</a>>
wrote:<br clear="none">
</div>
<blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>
<div>
<div dir="ltr">I just
tried as AS3340 in my
JP-6 and changing the
PW does affect the
pitch (mostly
noticeable in the
higher octaves). The
autotune can
compensate for it
though (adjust PW, hit
Tune button).</div>
<div dir="ltr"><br clear="none">
</div>
<div dir="ltr">Doug <br clear="none">
</div>
<div dir="ltr"><a shape="rect" href="http://synthparts.com" rel="nofollow" target="_blank">synthparts.com</a><br clear="none">
</div>
<div><br clear="none">
</div>
</div>
<div id="gmail-m_4658011309461797231gmail-m_-3570176100846851034gmail-m_8449761841727835596gmail-m_8796266394253402177gmail-m_2663333955044226633gmail-m_-8014807944889351604ydp5fb438c1yiv4177196667m_3476777082158557988ydpea96d023yahoo_quoted_7890612628">
<div>
<div> On Thursday,
December 19, 2019,
3:12:35 PM PST,
ColinMuirDorward
<<a shape="rect" href="mailto:colindorward@gmail.com" rel="nofollow" target="_blank">colindorward@gmail.com</a>>
wrote: </div>
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div>
<div id="gmail-m_4658011309461797231gmail-m_-3570176100846851034gmail-m_8449761841727835596gmail-m_8796266394253402177gmail-m_2663333955044226633gmail-m_-8014807944889351604ydp5fb438c1yiv4177196667m_3476777082158557988ydpea96d023yiv1930414145">
<div>
<div>
<div dir="ltr">Out
of curiosity,
does anyone
have an mks80
rev4 and/or
Jupiter 6 they
could test for
this problem? </div>
<div dir="ltr"><br clear="none">
</div>
<div dir="ltr">My
brother sold
his mks80 rev4
already, but
claims the
pitch error
was quite bad
in his unit.</div>
<div dir="ltr"><br clear="none">
</div>
<div dir="ltr">In
the next
model, the
rev5, Roland
apparently
switched the
3340 for a
proprietary
VCO chip. <br clear="none">
</div>
<div dir="ltr"><br clear="none">
</div>
<div dir="ltr">Colin</div>
<div dir="ltr"><br clear="none">
</div>
</div>
<br clear="none">
<div id="gmail-m_4658011309461797231gmail-m_-3570176100846851034gmail-m_8449761841727835596gmail-m_8796266394253402177gmail-m_2663333955044226633gmail-m_-8014807944889351604ydp5fb438c1yiv4177196667m_3476777082158557988ydpea96d023yiv1930414145yqt22023">
<div>
<div dir="ltr">On
Thu, Dec 19,
2019 at 3:48
PM Tom
Wiltshire <<a shape="rect" href="mailto:tom@electricdruid.net" rel="nofollow" target="_blank">tom@electricdruid.net</a>>
wrote:<br clear="none">
</div>
<blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>My own
view of it is
that if you
want cheap,
you buy the
Alfa AS3340.
If you want
original and
can afford it,
you buy the
CEM3340 G. The
V3340 falls
somewhere in
the middle and
therefore
doesn’t offer
a unique
selling point
for DIYers.
<div><br clear="none">
</div>
<div>Coolaudio
don’t care,
since
Behringer
needs tons of
‘em! ;)</div>
<div><br clear="none">
</div>
<div>
<div>Tom</div>
<div><br clear="none">
<blockquote type="cite">
<div>On 19 Dec
2019, at
13:53,
ColinMuirDorward
<<a shape="rect" href="mailto:colindorward@gmail.com" rel="nofollow" target="_blank">colindorward@gmail.com</a>>
wrote:</div>
<br clear="none">
<div>
<div dir="ltr">
<div>I didn't
see a lot of
discussion on
this topic
include the
v3340. Not
sure if people
had already
collected the
CEM and AS
versions by
the time the
Vs came out,
or what, but
the coolaudios
don't seem to
be on as many
work benches.</div>
<div> I just
checked a
neutron and no
surprise that
I could not
find any pitch
error there. <br clear="none">
</div>
<div>I have a
lot of
as3340s, so
when my next
prototype
comes in, I
could check
for error
variation
between chips.</div>
<div><br clear="none">
</div>
<div>Colin<br clear="none">
</div>
</div>
<br clear="none">
<div>
<div dir="ltr">On
Thu, Dec 19,
2019 at 10:01
AM Tom
Wiltshire <<a shape="rect" href="mailto:tom@electricdruid.net" rel="nofollow" target="_blank">tom@electricdruid.net</a>>
wrote:<br clear="none">
</div>
<blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">
<div>A quick
test on my
Pro-One
doesn’t reveal
any tuning
problem. I
routed the LFO
to PW on
oscillator A,
then listened
to Oscillator
A’s ramp wave
alone (so no
beating to
confuse
things) and
couldn’t hear
any
difference,
even with
maximum mod
depth and
maximum LFO
rate. Checking
the output on
the
oscilloscope
showed no
pitch
variation
either.
<div><br clear="none">
</div>
<div>That
said, there’s
some evidence
Sequential
*did* select
3340s. The
ones regarded
as “not good
enough” were
used for LFO
duties, and if
you check the
PCBs you’ll
see paint
blobs on those
ones. I’ve
never seen
anything
documenting
what the tests
were though.
Maybe they
just built the
things and
swapped out
any that
caused a
problem, put a
blob on them,
and then used
them later
where it
wouldn’t
matter.</div>
<div><br clear="none">
</div>
<div>A more
interesting
test which I
might get to
later would be
an A/B/C
comparison on
my 3340 test
board between
CEM3340 G,
AS3340, and
V3340. Despite
having all
three chips on
the shelf,
I’ve never
actually done
this.</div>
<div><br clear="none">
</div>
<div>Tom</div>
<div><br clear="none">
<div>
<div>
<div style="font-family:Helvetica;font-size:12px;font-style:normal;font-weight:normal;letter-spacing:normal;text-indent:0px;text-transform:none;white-space:normal;word-spacing:0px">==================<br clear="none">
Electric
Druid<br clear="none">
Synth &
Stompbox DIY<br clear="none">
==================</div>
</div>
</div>
<div><br clear="none">
<blockquote type="cite">
<div>On 19 Dec
2019, at
12:06, Mattias
Rickardsson
<<a shape="rect" href="mailto:mr@analogue.org" rel="nofollow" target="_blank">mr@analogue.org</a>> wrote:</div>
<br clear="none">
<div>
<div>I
remember
talking to
Dieter Doepfer
about this
back in the
day... Ah,
here it is:
<div><br clear="none">
</div>
<div>/mr</div>
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div><br clear="none">
</div>
<div><span style="font-family:sans-serif;font-size:12.8px">At
17:52
2003-02-02,
Dieter Doepfer
wrote:</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
>
-----Ursprüngliche
Nachricht-----</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> Von:
Mattias
Rickardsson </span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> Gesendet
am: Mittwoch,
29. Januar
2003 11:10</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> An: </span><a shape="rect" href="mailto:hardware@doepfer.de" style="text-decoration-line:none;color:rgb(66,133,244);font-family:sans-serif;font-size:12.8px" rel="nofollow" target="_blank">hardware@doepfer.de</a><span style="font-family:sans-serif;font-size:12.8px">; </span><a shape="rect" href="mailto:technik@doepfer.de" style="text-decoration-line:none;color:rgb(66,133,244);font-family:sans-serif;font-size:12.8px" rel="nofollow" target="_blank">technik@doepfer.de</a><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> Betreff:
A-111 problem?
(PW affects
Frequency)</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
></span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> Hi,</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> I have a
problem with
several of my
A-111 High-End
VCOs:</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
></span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> The
pulsewidth
(both PW knob
and PWM
input+knob)
affects the
frequency</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> of the
oscillator.
I.e., when
turning the PW
knob or PWM
modulating
with</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
> a slow
LFO, the
frequency
makes a
clearly
audible
change.</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>
>...</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">></span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>Dear
Mattias,</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>I
forward your
inquiry to our
A-111
specialist
Matthias
Marass</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>(mailto:</span><a shape="rect" href="mailto:keyboards@doepfer.de" style="text-decoration-line:none;color:rgb(66,133,244);font-family:sans-serif;font-size:12.8px" rel="nofollow" target="_blank">keyboards@doepfer.de</a><span style="font-family:sans-serif;font-size:12.8px">)</span><span style="font-family:sans-serif;font-size:12.8px">. He is responsible</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>for
the final
tests and
repairs</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">>of
the A-111. He
will answer
you directly.</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">At
15:36
2003-06-11,
Döpfer
Musikelektronik
-
Keyboardservice
wrote:</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">Dear
Mr.
Rickardsson,</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">the
influence of
the external
and internal
PW</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">control
voltage to the
oscillator
frequency is a</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">problem
of nearly
80..90% of the
CEM3340 we
ever</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">used.
Unfortunately
there is no
chance to
repair</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">this
problem. The
only way would
be a strict</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">selection
of the CEM3340
circuits.</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">...</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">Best
regards,</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
<span style="font-family:sans-serif;font-size:12.8px">Matthias
Marass</span><br style="font-family:sans-serif;font-size:12.8px" clear="none">
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<div dir="ltr">Den
tors 19 dec.
2019
10:42Oakley
Sound via
Synth-diy <<a shape="rect" href="mailto:synth-diy@synth-diy.org" rel="nofollow" target="_blank">synth-diy@synth-diy.org</a>>
skrev:<br clear="none">
</div>
<blockquote style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"> >
... "So as a
conclusion the
goal is to
have on pin3
as close as <br clear="none">
possible to
-5V and the
PWM to tune
error will not
manifest
itself."<br clear="none">
<br clear="none">
I did not find
this to be the
case since I
always run any
3340 circuit <br clear="none">
from a
precision 5V
reference. The
solution for
me was to get
the <br clear="none">
CEM3340 rev G.
The CEM3340
has the detune
too, it's just
that it is <br clear="none">
quite small. I
can't remember
exactly, but I
think it's in
the region of
<br clear="none">
+/-1 cent. It
would almost
certainly be
there on the
SH-101.<br clear="none">
<br clear="none">
Alfa's
solution is to
use the newer
AS3340-HYB.
The other
thing to do is
<br clear="none">
make your own
triangle or
saw to pulse
wave convertor
from an op-amp
or <br clear="none">
comparator
external to
the chip.<br clear="none">
<br clear="none">
When repairing
an OB-Sx I
found that the
AS3340 did not
work well as a
<br clear="none">
sub for the
original
CEM3340. Even
with the
various
resistor
changes <br clear="none">
required to
get the AS3340
to work
properly, the
VCOs in last
three <br clear="none">
voice card
positions on
the
motherboard
displayed a
very audible
pitch <br clear="none">
instability at
pulse widths
at less than
45%. Clearly,
there was some
<br clear="none">
layout issue
but although I
tried all
sorts of
things
(including bus
bar <br clear="none">
0V and liberal
dousing of
capacitance)
it wouldn't
solve the
problem. <br clear="none">
Again, the
solution was
to replace all
the VCOs with
CEM3340 G.<br clear="none">
<br clear="none">
Tony<br clear="none">
<br clear="none">
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