Olson XX-100 Rhythm Beat modification

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blackelmo
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Olson XX-100 Rhythm Beat modification

Post by blackelmo » Thu Jan 09, 2014 1:24 pm

Hi all,
I have an "Olson XX-100 Rhythm Beat" drum machine that I would like to modify by adding gate/trigger inputs for each sound. I was thinking that it would be simple to modify because there are trigger buttons on the front of the unit. Do you think I could just connect a 3.5mm jack to each of the buttons contact points and it would respond to trigger/gate voltages?

I'm very much a novice DIY electrician and maybe I'm oversimplifying what is needed to make this work.

Any advice would be appreciated. Thanks!

EDIT: After thinking about it some more, it seems there would need to be a transistor or something to convert the incoming voltage to an on/off signal like the connection being made with the pressed button.
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Piedwagtail
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Post by Piedwagtail » Thu Jan 09, 2014 10:03 pm

Get a Digital Multimeter with Voltage, Current, Resistance and Continuity, spend some money for your future(don't skimp).

Get detailed photographs of the inside (power off)

.....

Report back with photographs.

Wigglers can then help you.

blackelmo
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Post by blackelmo » Sun Jan 12, 2014 10:28 pm

Thanks! Photos coming shortly...

blackelmo
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Post by blackelmo » Sun Jan 12, 2014 10:35 pm

TOP
Image
BOTTOM
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BOTTOM DETAIL
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FRONT PANEL REFERENCE
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I have higher resolution details available too.

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plugugly
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Post by plugugly » Mon Jan 13, 2014 2:45 am

Yes sir!

All you really need to do is place an NPN across each button contact. The most complex thing you'll need to know for this is which contact has a higher potential, as this contact will be be attached to the transistors collector.

You may want some input conditioning. The following was quickly modelled after Thomas Henry's UD-1 trigger input and may work well for you. Removing the capacitor and resistor on the positive input would allow the comparator to respond to any input waveform....which also may be useful for you.

Either way, to wire up all 8 buttons it's just a handful of parts.

Image

Perhaps someone else can chime in with some options?

Edit: It would be a bit more complex, but you could also explore trigger controlling the rhythm selector and voltage controlling the tempo. Could be pretty cool.

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Piedwagtail
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Post by Piedwagtail » Mon Jan 13, 2014 1:15 pm

OK, from what I can see.

Two boards plus switch board. Top is voice board.Bottom with long traces is lfo/ flipflop counters and diode rhythm presets.Switches trigger to this.

Standard two pin 60s/70s power, no connection to mains earth.
Chassis is ground.
Screws to chassis, so all the big traces around the pcbs are at ground potential. Put your negative/black multimeter prong to these. Scratch it a bit if the pcbs are dusty/greasy/varnished.

The other side of the transformer will probably have two terminals/wires these will connect to the boards after the rectifier.Look which wire attaches to those big ground traces gives you the ground 0V. You can use the continuity test of the meter to confirm this ie.connect across the bits you think are connected.

Get the item on a stable surface and power on with covers removed.
There will be mains potential coming in and travelling to the on/volume switch and back to transformer.You could trace that and make a mental note.There's live terminals at the fuse holder to keep your hands well away from.
Covering these and any bare wire/soldering with tape is a good idea, at least while you got it open.
The terminal strip by the transformer may have an exposed mains potential as well. Keep these in mind; this is less safety conscious old manufacture and it doesn't hurt to trace and measure AC voltages through the inlet side so you know where you stand.

OK, the reason for all this is so you can confirm the polarity of the power rail.
Many of the first transistor rhythm machines are powered by a negative rail.The Bentley Rhythm Ace is -14V for instance. The reason is that early transistor fabrication favoured the pnp rather than the npn - they were cheaper to use.
So the other wire will give you the voltage potential of the power rail.
(If the power rail is negative the - of the power supply cap will be to this not the ground as we are used to in modern convention).The meter will show polarity between the prongs.

You can now also read the terminals of the switches how they are connected- shorting to ground or shorting to power rail.
If you want to fire the triggers from a usual +5v or +10V positive edge trigger then once you know the way the switch triggers then the appropriate connection/circuit can be inserted.



Robert

blackelmo
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Post by blackelmo » Fri Jan 17, 2014 8:07 pm

Thank you both for the detailed replies. I now have a digital multimeter as suggested. I'll probably have some more questions as I begin the project.

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Piedwagtail
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Post by Piedwagtail » Mon Jan 20, 2014 8:38 am

Poke around....
And take notes of what you discover/try/wonder.

Robert

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sines
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Post by sines » Thu Jul 27, 2017 10:15 pm

blackelmo wrote:Thank you both for the detailed replies. I now have a digital multimeter as suggested. I'll probably have some more questions as I begin the project.
Any luck with this? About to do the same thing.


Todd

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sines
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Post by sines » Fri Jul 28, 2017 11:01 am

Can someone who actually owns an X 100 send detailed photos of the voicing board? After prodding around the headphone jack I'm realizing that someone mined this board for parts, as there is a trimmer missing. Currently getting zero audio and the missing parts are probably the reason why.

Please view the attached images. Thanks!
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sines
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Re: Olson XX-100 Rhythm Beat modification

Post by sines » Sat Sep 12, 2020 7:51 am

*bump* no responses in 3 years, anyone got any ideas, or at least, photos of their own XX-100 — specifically the top and bottom of the voicing board?

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