Korg Forums

pax-eterna.1 · Senior Member Joined: 03 May 2017 Posts: 393

The used M3 I have recently acquired has a Radias EXB board fitted but no ribbon cable.

Looking for help to locate one of these please.

Even just a picture of both ends of the cable would do so at least I can make one!

And its impossible on the internet there is NOTHING directly relating to the cable!!![/i]

pax-eterna.1 · Senior Member Joined: 03 May 2017 Posts: 393

Can a Radias owner please help out here?

voip · Platinum Member Joined: 27 Nov 2014 Posts: 3769

Also posted on the Radias/R3 section:

The images in the link below might help a bit.

https://reverb.com/item/52083814-korg-exb-radias-expansion-klm-2027-m3-mmt-synthesis-24-voice-vocoder-radias-incl-mounting-screws

The cable seems straightforward enough. Measure the connector pin spacing on the board as accurately as possible, and also the connector on the M3 itself. Find the pin 1 reference on the silk screen printed on the EXB-Radias PCB and also the M3 connector.

The connector on the M3 is a Samtec part, STMM-110-02-G-D-SM-K-TR, which is 2.0mm pin spacing, so look for the mating IDC (insulation displacement connector). Check that the connector on the EXB-Radias is the same. The ribbon cable will need to be 1.0mm spacing.

pax-eterna.1 · Senior Member Joined: 03 May 2017 Posts: 393

voip · Platinum Member Joined: 27 Nov 2014 Posts: 3769

Hmm, that's interesting. There's an image of the underside of the EXB-RADIAS board in the link below. In that image, the through hole pins for the ribbon cable connector look definitely non-offset. Offsetting is generally used in insulation displacement ribbon cable connectors, to allow for simple cable assembly. The IDC wire receptacles for the odd numbered pins are displaced one way, whilst the even numbered pins are displaced the other way. When the ribbon cable is inserted and squeezed by the assembly tooling, the odd numbered pins line up and connect to the odd numbered ribbon conductors, and similarly for the even numbered pins.

https://reverb.com/item/29049510-korg-exb-radias-2010

Could it be that the ribbon cable connector end is still fitted to the board, minus the ribbon cable, or that the ribbon cable IDC part is directly soldered to the board?

A possible starting point might be this, where one end of the cable assembly is soldered directly to the EXB-RADIAS board:

https://uk.rs-online.com/web/p/ribbon-cable/0159543
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pax-eterna.1 · Senior Member Joined: 03 May 2017 Posts: 393

voip · Platinum Member Joined: 27 Nov 2014 Posts: 3769

If you look at the cable assembly drawing link in:

https://uk.rs-online.com/web/p/ribbon-cable/0159543

i.e. https://docs.rs-online.com/0a84/0900766b809a6d32.pdf

it shows the holes in the header in the offset positions as you described.

In fact, the cable from RS may even do the job, as supplied. The original header will need to be desoldered from the EXB-RADIAS board, and replaced with the male headed connector of the RS cable (RS stock number 159-543). Hope this makes sense.

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pax-eterna.1 · Senior Member Joined: 03 May 2017 Posts: 393

Thanks,

while the de-soldering is not a problem for me, I am not sure I should really be doing that. I assume Korg have those pins aligned in that way for a reason.

The headers also seem to be slightly different in length and design in an other aspect. If you look at the EXB board there is a clear gap at either end (with 20 pins in between) and on the M3 there is no clear space at either end, the pins are essentially "end to end" if you get me.

The more I look at it the more I think Korg (probably to increase after-market sales???) have deliberately made the EXB connector bespoke.