The Korg Mini-Pops 120, also rebranded as the Univox SR-120, was the top-of-the-line Mini Pops model produced, with more features and presets than other drum machines from this series, such as the Mini Pops Junior and 35. It comes in two cabinet styles, a tolex road case or a wooden chassis. Apart from their appearance, both units are identical in every other aspect. My tolex 120 came with a huge “Boss” sticker stuck on it… I couldn’t remove it, I thought it was too funny, Roland being Korg’s biggest competitor in the drum machine market at the time!
There are 16 presets, each of which has two variations, five “fill-in” settings that can be triggered every 2,4,8,12 or 16 bars, plus the ability to alternate between variations A and B of the selected rhythm. This change, and also the “fill-in”, can be automatic or manual. There’s also a fade out/in button, with a long/short setting. The unit has a mono output, and no trigger out. There are five jacks: hi-fi out, guitar amp out, start/stop, fade out/in, manual.
It has a raw sound, much rougher than Korg’s next series, the KR-55/KR-55B drum machines. Basically the sound voices are still very “first generation”, similar to the Rhythm Aces, although with more options for variation. The closest Roland drum machine to this unit, at least in terms of features, is probably the TR-66 Rhythm Arranger.
Technical Info / Service Notes
Below are some instructions on how to modify the unit for separate outs, some troubleshooting information, a copy of the owner’s and service manuals.
Rhythm pattern storage
The first thing to mention is that this unit stores its presets on a ROM chip, which is pretty much impossible to replace unless you rip it from another machine. Older drum machines, such as the Ace Tone Rhythm Ace series, stored their presets with an array of discrete components, which means that they can pretty much always be repaired if one’s willing to put some time into it.
Not so with the Mini Pops 120 (and many others, such as the Roland CR-68). When I bought my first one, for a very cheap price, I quickly found that everything seemed to work, including all the voices and buttons, but every preset output the same thing: one hit on every beat, albeit with different voices depending on the preset. Obviously the rhythm patterns were lost either in the ROM chip, or somewhere on the way to the voice generator board. After quite a lot of poking around, I came to the conclusion that the ROM chip wasn’t outputting the rhythm patterns.
I must admit that I’m not 100% sure that the chip is dead, as I’m not very experienced at digital electronics troubleshooting. But I’m pretty sure that’s where the problem lies. So if you’re planning to buy a drum machine, and the seller tells you everything works except all the beats are the same, be warned: it might not be an easy fix…
Fortunately, the second unit I bought still had intact patterns, but the cymbals and hi-hat sounded terrible, more like a farting overloaded speaker than a high-pitched ring… A detailed inspection of the insides revealed the problem: all the 100mf electrolytic capacitors on the main board had leaked, in some instances damaging the traces and cutting some connections. The other value capacitors were OK, so probably the 100mf caps came from the same defective batch. If that’s the case, my Mini Pops 120 is probably not the only one with this problem.
After replacing the leaking caps and restored the severed connections, I turned the Mini Pops back on and my cymbals came out loud and clear, just as they were supposed to be. My unit was back to normal, so I turned my attention to getting individual outputs…
Separate outputs modification
After poking around for a while, I found patch points for all the sounds, and decided to rewire all five jacks with individual voices separated like this:
Cymbals / Hi-Hat
Low and high conga
I had a bit of trouble isolating the bass drum from the other voices, but by turning the tone knob all the way down, I could barely hear the other voices, so I decided to go with it. I had found some louder, more isolated bass drum taps on the circuit board, but they had a very different tone and attack, not very pleasant. They probably needed to be damped by other parts of the circuit, so in the end I went for the tap with the best tone.
|Manufacturer||Keio Electronic Lab., Corp. (Tokyo, Japan)
|Date||1976 (according to schematics)
|Sounds||6 (BD, SD, Cy/HH, low conga, high conga, claves)
|Presets||16 (slow rock, swing, bossa nova, beguine, rumba, mambo, samba, waltz, tango, polka, foxtrot, march, rock 1 to 4)|
|Programmable||No, but has rhythm auto change and automatic break/fill.|
|Controls||- Tone balance control
- Long/short fade out/in
- Manual 'break' button
|Outputs||2 (same signal)|
|Footswitch||3 (start/stop, fade in/out, manual break)|
|Related models||Identical to the Univox SR-120. Similar to other Korg Mini Pops models, and to the Roland TR-66.|