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 Forum index » DIY Hardware and Software
Korg Minipops
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Mon Nov 30, 2009 11:43 am    Post subject: Korg Minipops Reply with quote  Mark this post and the followings unread

Hello all. Im looking for any info (esp a schematic) for my minipops jnr. Does anyone know if the start/stop control is just a shorting footswitch type or something else? Question

I'd like to try and modify it to sync upto my other analogue gear as the tempo control is via a 500k pot Very Happy

Hope this is the correct area to post!

Thanks, Mark
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Mon Nov 30, 2009 1:47 pm    Post subject: Reply with quote  Mark this post and the followings unread

UPDATE!!!........

Just secured an Ace Tone FR8.........Which also has a Start/Stop jack...

While I was looking for info I discovered a guy on youtube who has midi'd his earlier Rhythm Ace with stunning results! Needless to say this looks like a plan.....

Any info on the FR8 would be fantastic!!
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opg



Joined: Mar 29, 2004
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Location: Berkeley, CA, US
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PostPosted: Mon Nov 30, 2009 2:08 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey - I was just digging around and found out that the Rhythm Ace was a product made by the guy who started Roland! There are tons of free manuals for Roland equipment, but I doubt they'd go back that far. Smile

Do you have a website of some tunes of yours? I've collected a handful of old drum machines and have been working on some tunes with them.

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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Tue Dec 01, 2009 6:36 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey One Player Game, thanks for the reply. I've just had a knock at the door and it was the ebay vendor, FR8L under arm! Still in the original box and it only really needs a quick squirt of contact cleaner and a wipe down with a damp cloth! Not bad considering I only won it last night! Very Happy

Further to your post I did some digging myself. Sound On Sound carried a very informative history of Roland a few years back with a breakdown of the Ace Tone/Roland/Multivox/Boss relationship:

<http>

Well worth a read if you get half an hour.

Ive done some tunes myself over the years but not really in an experimental sense, move your run of the mill beats/samples/synths but Im still learning things from an electronic point of view (buying most of what I use faulty/dead and repairing where necessary) hence my desire for obsolete schematic diagrams!Laughing

Thanks again for the reply, if i get time I'll post some pics. Need to research the midi interface the dude on youtube was using with an earlier Ace Tone. He was triggering it from a (Davy) DX drum machine and he mentioned the interface was originally designed for the Atari 2600. I'll have to dig out the youtube link....

Thanks again, Mark.
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Tue Dec 01, 2009 6:41 am    Post subject: Reply with quote  Mark this post and the followings unread

S.O.S link....

http://www.soundonsound.com/sos/nov04/articles/roland.htm

With MIDI Razz Razz

http://www.youtube.com/watch?v=ZxMTwfx1sjo&feature=related
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LektroiD



Joined: Aug 23, 2008
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PostPosted: Tue Dec 01, 2009 10:50 am    Post subject: Reply with quote  Mark this post and the followings unread

Everything you need is in the Korg Minipops thread:
http://electro-music.com/forum/topic-35600.html

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bunker



Joined: Mar 19, 2009
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Location: Manchester, UK

PostPosted: Tue Dec 01, 2009 2:19 pm    Post subject: Reply with quote  Mark this post and the followings unread

LektroiD wrote:
Everything you need is in the Korg Minipops thread:
http://electro-music.com/forum/topic-35600.html


Thanks, I'll take a look there! Very Happy
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opg



Joined: Mar 29, 2004
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PostPosted: Tue Dec 01, 2009 4:43 pm    Post subject: Reply with quote  Mark this post and the followings unread

bunker wrote:

While I was looking for info I discovered a guy on youtube who has midi'd his earlier Rhythm Ace with stunning results! Needless to say this looks like a plan.....


I figured you'd come across the MIDI version. Smile Awesome.

BTW, what I'm doing with my analog drum machines:

I have two Tama Techstar drum modules (two in each, so that's four), a Syndrum module, and a few Roland dealies which are of course only CV-triggered. However, I have a Yamaha RX-11 drum machine that has individual outputs for each sample that I can trigger via MIDI. I haven't looked at the schematics for that guys MIDI "retrofit," (I'm not sure he's posted them or not), though. His, although requiring circuit work, probably sounds a bit cleaner.

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bunker



Joined: Mar 19, 2009
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Location: Manchester, UK

PostPosted: Tue Dec 01, 2009 5:16 pm    Post subject: Reply with quote  Mark this post and the followings unread

Mmmm...those chunks of analogue sound nice! Ive just got the Minipops jnr and the FR8L.
The FR8L turned up today and I set to work with a full service. A chump decided at some time it would be a good idea to glue the caps onto the slider stalks so I can't get the front panel off to get to the switches (in dire need of cleaning), but the sliders benefited from a quick blast of contact cleaner.

Did a bit more digging and Highly Liquid do a pile of 8 channel MIDI decoders with relay or transistorized outputs amongst others. Look pretty good on price too.

This is the controller he modded....

http://highlyliquid.com/kits/midi2600/

But maybe it would be easier with one of these, maybe the +5v output model....

http://highlyliquid.com/kits/md24/

I've got a copy of the service docs for the FR8L on the way so if you need any info, please let me know.

BTW I had a listen to some of your tracks before, Very Good! I like a lot, keep it up!

Mark.
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opg



Joined: Mar 29, 2004
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PostPosted: Tue Dec 01, 2009 7:12 pm    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for the kind words.

Those kits look great! Very affordable, even if you pay the extra for assembly. Not surprised that the SKM 2 is discontinued Wink

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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Thu Dec 03, 2009 6:35 pm    Post subject: Reply with quote  Mark this post and the followings unread

Hey opg, I got the FR8L service manual by mail today. There are a couple of pages of circuit description in typical early 70's Japanese-to-English translation which makes humorous reading Very Happy Very Happy as well as circuit diagrams and pcb layouts.

I've not really studied the diagrams yet but it would appear that the diode matrix triggers the oscillators for each drum in the pattern and there looks to be 13 drums sounds withe some also adding varying levels of noise to different waveforms. There is quite a bit of control over the voices via trimpots but my only complaint is the low level of the kick drum in comparison to the other voices and the lack of a trimpot for the level. It shouldn't be a big job to amplify the level of the kick drum tho with a bit of stripboard and a couple of transistors. Very Happy

Interestingly there looks to be space on the board for another inductor and is associated components to give a tambourine voice. This is the same situation as mentioned in the minipops thread whereby the Korg and Univox machines share a circuit board but with different voicing. I'm guessing the TR77 has the tambourine while the Ace Tone doesnt. I've not seen a schematic for the Roland so I don't know what value of components to use but there is a post from someone saying they have the inductors so I may go down that route.

Anyhow, back to the scope and schematic to suss how to midify my beatbox!!
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opg



Joined: Mar 29, 2004
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PostPosted: Fri Dec 04, 2009 7:31 am    Post subject: Reply with quote  Mark this post and the followings unread

Diode matrix. That's so old school Smile

That sounds awesome! Keep me posted. I may need your help later down the road with two Roland ones I'd like to tweak Cool

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nuipb



Joined: Oct 06, 2009
Posts: 47
Location: France

PostPosted: Fri Mar 26, 2010 1:51 am    Post subject: Reply with quote  Mark this post and the followings unread

Hi Mark, did you successfully MIDIfied your FR8L in the end ?
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bunker



Joined: Mar 19, 2009
Posts: 58
Location: Manchester, UK

PostPosted: Sun May 12, 2013 6:13 am    Post subject: Reply with quote  Mark this post and the followings unread

Hey nuipb, sorry for the delay Embarassed Embarassed . I didn't get it done yet but its definitely a job for the future. Just as soon as I've got my head around PIC programming! Rolling Eyes
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nuipb



Joined: Oct 06, 2009
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PostPosted: Sun May 12, 2013 10:38 am    Post subject: Reply with quote  Mark this post and the followings unread

Thanks for remembering !
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blakeAlbion



Joined: Jun 16, 2020
Posts: 23
Location: Boston, Massachusetts, USA

PostPosted: Sun Mar 13, 2022 12:09 pm    Post subject: Scarcity of Minipops documentation Reply with quote  Mark this post and the followings unread

To my knowledge, there are Mini Pops 7 , Mini Pops 120, Mini Pops (0) service manuals out there. Apparently there was a Mini Pops 5 service manual. But I have seen no evidence of a Mini Pops Junior service manual. Perhaps they were just disposable.

We are fortunate to have the Mini Pops 7 schematics. But, the Mini Pops Junior aka Univox JR-5 is a queer bird. I'm guessing it was made after the golden age of Mini Pops, and it seems to be somebody's effort to make a simplified home rhythm unit with a reduced part count. The concepts shown in the Mini Pops 7 manual are basically the same but a few important parts seem to be mutated for cheapness.

1) The tempo oscillator seems to have been simplified so that the trim pot has a narrow sweet spot. And unlike other Mini Pops machines, this is not a coarse or fine adjustment for tempo, it seems to adjust the voltage and shape of the rise/fall of the clock signal. A small adjustment can throw off the flip flops and truncate the pattern. On YouTube you can see people powering up an old Mini Pops JR and you hear this. On my unit it's temperature sensitive: it needs to warm up before I'm getting 16-step patterns.
2) There's no "preamp" as far as I can see; all the sounds are mixed with resistors and fed right into the output amp. There's little headroom and adding knobs to attenuate the sounds runs the risk of a noisy mix.
3) Worst of all is the power supply. It appears the Mini Pops Junior has a single power diode and two stages of RC to smooth out the DC power. After recapping everything I can't get rid of the baseline hum. It's around 20V and has barely enough current to power the board. Adding any additional circuitry runs the risk of creating a voltage drop that throws the pattern generator off.

I can imagine someone beefing up the PSU and adding an active mixer and individual outputs would need buffering too. But these are 5 very cheap sounding voices. Do they deserve the love?

I'm doing my best to modify my Univox JR5 without adding those big-ticket items, and I am running into the fundamental problem of poor audio quality.
Perhaps I am putting too much lipstick on my pig.


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