What is the safest way to extend the Monotron ribbon?

[Esppse]

Hello,

I'm modding this into a larger home, I need a couple extra inches on the ribbon connector. How does one extend this wire? Would you be able to solder onto those 3 lanes, or will that fail to melt onto it?

http://electro-music.com/forum/phpbb-files/thumbs/t_monotron_ribbon_430.jpg

I'm not sure if the wire is resistive material, or just conductive material, or how to safely splice 2 inches of hookup wire to it.

Thank you

[Esppse]

Mmm can I put solder onto the 3 lanes perhaps, I'm afraid to cut the ribbon in half to try it.

[anotherjim]

Can you remove the pcb connector, keep that plugged on the flexi and extend between?
I don't know for sure. There could be 3 etched copper tracks on the flexi or it could be something sputtered/printed that will vapourize/oxidize with solder heat.

[Esppse]

Turns out it was the latter and did indeed vaporize with solder heat.....

Oh now I'm absolutely clueless on how to proceed with this project

[reddesert]

The Monotron and Monotron Delay schematics are publicly available (big ups to Korg) https://www.korg.com/download/global/monotron_schematic/monotron_sch.pdf and the ribbon is shown in the upper left corner.  The ribbon is depicted as a 10K potentiometer wired as a voltage divider between Vcc and ground. I think it's a safe guess that the flexible connection is just something conductive between the actual ribbon and the connector onto the PCB. However, these things are really thin and too fragile to take heat. (I have a similar printed flexi connector that I physically tore in an electronic camera lens and have never got around to fixing.)

If you have a significant part of the flexi connector remaining, you could try to make a mechanical connection to the conductive tracks, using something that pierces/crimps onto them - like an IDC, though I'm not sure an IDC for ribbon cable would work on it.

[anotherjim]

Get some silver conductive paint - the stuff used to repair autoglass heating strips?

[Kevin Mitchell]

Sorry I quickly scanned through the thread. But I wanted to leave this here;
Soft Pot Strip;
https://www.sparkfun.com/products/8681

[Esppse]

Thanks for the many suggestions, I think repairing it has been to no avail. The ribbon is too fragile to crimp unfortunately. I've ordered the 10k softpot from Adafruit, it's 100mm, which is exactly the same length as the original. I will update to verify if this part works.

[Mark Hammer]

Why not snag any of the cheap keyboards that show up regularly on 2nd-hand sites, and adapt the keyboard to use a string of 1% fixed resistors in place of the ribbon?

[Kevin Mitchell]

Fixing a resistor string on a keybed is not a great idea. Especially if the device is made for a soft pot you'll have to do some hacking to fit a different keybed in there if that's even possible - along with a bus bar or a contact board but most keybeds nowadays use a diode matrix and a micro controller so you'd have to hack that as well or build your own controller. A resistor string would also omit the aftertouch capability that soft pots produce. Though... many modern keybeds have softpots in them for aftertouch so you could just rely on that. But again - likely wont find one that fits your unit unless it's a generic keybed which the monotron doesn't seem to have.

More trouble than it's worth for sure.

EDIT: I didn't realize the monotron could fit in your pocket! Well... I deserve an award for redundant posts.

[Mark Hammer]

I have a Monotron Delay that I hope to fit a keyboard with resistor string to....eventually.  Too many other things to get to first.

[Esppse]

OK I have verified the Adafruit one to work.

However it is a little too long compared to the Korg, about 20cm longer I think, I didn't get an exact measurement.

Second, pins 2 and 3 are reversed on the Adafruit ribbon. Otherwise a good replacement, easy to solder to.

[anotherjim]

Good to know the Adafruit supplied part worked.
I can be possible to play the thing from a standard CV/gate, but with only 5v power on board, the control needs scaling down with resistors and you may have to accept poor pitch linearity.