Mono/Poly variations

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Synthazaiser
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Mono/Poly variations

Post by Synthazaiser » Fri Jan 11, 2008 2:06 am

I just learned that there are two different versions of the mono/poly. It looks like the later version had 33kohm resistor between the VCO out and SSM, where as the earlier version has a 47kohm resistor. How could I tell, without taking apart the synth, if I have a new or old version? Does anyone know at what point in the serial numbers this change was made? Also, could the resistors in an old version be changed to the new value and safely work? My Mono/Poly is serial number 371801.
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brian.only
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Post by brian.only » Fri Jan 11, 2008 6:22 am

Interesting, I had no idea- any engineering types around know what the difference would be between the two hypothetically?
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Post by steveman » Fri Jan 11, 2008 12:06 pm

According to this site: http://monopoly.highspies.com/oscsec.html earlier models had a digital noise source, while later models used an analogue noise source.

Not sure what difference the resistor would make - unless you understand this: http://www.emulatorarchive.com/assets/P ... rcuits.pdf

Can't see it's worth worrying about.

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Dirk
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Post by Dirk » Fri Jan 11, 2008 6:43 pm

Here are the differences of the two versions.
http://www.emusic-diy.org/KorgManuals/M ... =mp_07.gif
http://www.emusic-diy.org/KorgManuals/M ... =mp_08.gif

Main difference is the voltage divider that is made up of R1 and R3. The new version allowes twice the amount of voltage to the filter. It's an eazy fix for any person that can solder. You can ofcause make the voltage divider so that it even allowes more voltage into the filter for serious filter overdrive. Just make R3 bigger, 1k-5K should give you extreme filter distortion (but try a small potmeter here). And you can alway's turn the VCO level's down with the mixer. I haven't tried to change R3, so it's not tested.

The monopoly of my friend has serie number 375233 and is the new version.
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OriginalJambo
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Post by OriginalJambo » Fri Jan 11, 2008 10:09 pm

Dirk wrote:The monopoly of my friend has serie number 375233 and is the new version.
Thanks for that.

As my serial number is 376697, I think it's most likely the of newer production run.

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