<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
</head>
<body text="#000000" bgcolor="#FFFFFF">
I found the reset and battery voltage sufficiently insane. It needs
to be completely rethought. I don't know how they got where they
did, but a friend of mine made a MIDI processor out of TTL gates, so
I guess anything's possible.<br>
<br>
<br>
<div class="moz-cite-prefix">On 3/11/2020 3:59 PM, John P Shea
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAFBTNJdvoDZ8rhYzXbAm0C6NXN2x+MtjwrTxQ-jiE9HGWaWqAQ@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="ltr">
<div>Hi MTG,</div>
<div><br>
</div>
<div>Don't get too freaked out! Without even looking at the
schematic, you'll know that it's an 80's era (probably 8-bit)
era microprocessor, perhaps even an early microcontroller. To
support the CPU, it will typically need a clock circuit, and
no doubt there will be power on reset handling.</div>
<div><br>
</div>
<div>The micro will need to execute a program, and this will
probably be in an external ROM. Similarly, you need to store
those presets, so some (battery back up) RAM in there too.
Now, the CPU will have to process inputs. What inputs are on
this synth?</div>
<div><br>
</div>
<div>Firstly, it will need to do keyboard scanning. The CZ-1000
is 4 (x2 osc) or 8 note (x1 osc) polyphonic, so the scanner
will be some sort of rows and cols jobby.</div>
<div><br>
</div>
<div>Moving on, it will also need to handle the buttons. Another
scanner possible.</div>
<div><br>
</div>
<div>Any other inputs? Yes, MIDI DIN, do there will be the opto
and serial circuitry for this.</div>
<div><br>
</div>
<div>Now for outputs. Obviously, we have the phase distortion
audio out, probably handled via an outboard DAC and
filter/buffer. Next, we have digital outs, including the
button LEDs, the LCD, and MIDI Out, which could be just a 5V
non-inverting buffer.</div>
<div><br>
</div>
<div>To handle all of those peripherals, the CPU sends
(probably) 8 data lines to each. And to uniquely address each
one, there will be address decoding circuitry, look for the
"CS" or chip select on each of the peripheral chips.</div>
<div><br>
</div>
<div>The point is, this is a known pattern. Because there will
be a lot of Japanese specific chips in there, it may may
finding individual data sheets a bit tricky. But its just a
micro with some peripherals at the end of the day!</div>
<div><br>
</div>
<div>All the fun part is in the ROM :)</div>
<div><br>
</div>
<div>Regards,<br>
</div>
<div>JPS<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Thu, 12 Mar 2020 at 02:00,
MTG <<a href="mailto:grant@musictechnologiesgroup.com"
moz-do-not-send="true">grant@musictechnologiesgroup.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">Wow,
that (original) circuit is insane. Hopefully someone on this
list <br>
can understand all of it because I sure can't.<br>
<br>
On 3/9/2020 9:31 PM, Joe Frey wrote:<br>
> Hello all, To those that answered my original post asking
for guidance I <br>
> found the problem. The output relay had gone bad and
needed to be replaced.<br>
> <br>
> So, after getting the synth to sound good again I decided
to make an <br>
> improvement and add ram power management so my custom
patches wouldn't <br>
> disappear when I put the synth in it's case for half a
year. It turns <br>
> out there's a chap that made a mod that I found out about
that people <br>
> say works. I contacted him and though he no longer
provides the kit he <br>
> did supply the info to make that mod.<br>
> <br>
> <a href="https://www.artefacts.nl/bitsandpieces.html"
rel="noreferrer" target="_blank" moz-do-not-send="true">https://www.artefacts.nl/bitsandpieces.html</a><br>
> <br>
> He also gave this advice, "_Before you start modifying
the CZ you should <br>
> check if you can change the standby voltage as described
in the <br>
> installation manual_. You should also check the RAM chips
get a voltage <br>
> between 4.8Volt and 5.2Volt when the unit is switched on.
If you can not <br>
> get these voltages within range the kit will not work."<br>
> <br>
> Of course being me, I ignored the first line of the
instruction and made <br>
> and installed the mod. DOH! Now, everything is cozy and
in place but I <br>
> can't use the trimmer to get the standby voltage down to
3.2V. I can get <br>
> it to 3.7V. I am wondering if I put a diode in the end of
the VBR <br>
> regulator circuit to use the diode drop and try and get
from 3.7 to 3.2V?<br>
> <br>
> The schematic is found here.<br>
> <br>
> <a
href="https://www.synthxl.com/wp-content/uploads/2018/01/Casio-CZ1000-schematics.pdf"
rel="noreferrer" target="_blank" moz-do-not-send="true">https://www.synthxl.com/wp-content/uploads/2018/01/Casio-CZ1000-schematics.pdf</a>
<br>
> <br>
> <br>
> And the VBR power supply is at page 4, grid 4F. And, the
ribbon cable <br>
> pin I am measuring voltage at is pin 9.<br>
> <br>
> Any advice is appreciated. JoeF.<br>
> <br>
> _______________________________________________<br>
> Synth-diy mailing list<br>
> <a href="mailto:Synth-diy@synth-diy.org" target="_blank"
moz-do-not-send="true">Synth-diy@synth-diy.org</a><br>
> <a
href="http://synth-diy.org/mailman/listinfo/synth-diy"
rel="noreferrer" target="_blank" moz-do-not-send="true">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>
_______________________________________________<br>
Synth-diy mailing list<br>
<a href="mailto:Synth-diy@synth-diy.org" target="_blank"
moz-do-not-send="true">Synth-diy@synth-diy.org</a><br>
<a href="http://synth-diy.org/mailman/listinfo/synth-diy"
rel="noreferrer" target="_blank" moz-do-not-send="true">http://synth-diy.org/mailman/listinfo/synth-diy</a><br>
</blockquote>
</div>
</blockquote>
<br>
</body>
</html>