How to make a replacement for the 82S123 ROM chip (ADS-1 board – U19) in Ursa Major Space Station SST-282, using an 22v10 Programmable Logic chip and a cheap EPROM programmer. I used Atmel ATF22v10CQZ-20PU and the common TL866iiPlus. This is not a step-by-step guide, you are expected to know how to use an EPROM […]
This page compares the Roland MKS-7 to the Roland Juno-106. To understand it, you need to know the Juno-106. Some people say the MKS-7 is the rack version of Juno-106. But it’s more… and less. The Roland MKS-7 was allegedly intended for MIDI-file playback and karaoke, thus being a consumer market product. The voicing hardware […]
While servicing an Arp Sequencer 1621, I noticed that the three button switches were in a bad shape. One button press would produce anything from one to six signal changes. These switches can’t be sourced nowadays. The switches are glued together from factory so they can’t be opened. One possible fix would be to fit […]
It was pointed out to me that there is already a modification devised by Korg for this purpose. While my modification works, you should probably stick to Korg’s original Engineering Change Note, even though it’s a bit more complex. The Korg Poly-61 has the same type of battery as the Korg Polysix, the type that […]
Descriptions of Individual Audio Outputs modifications for the Roland TR-505 have been around for a while. I searched the web for sources that describe how to do the mod: https://www.circuitbenders.co.uk/drummachine/TR505.html https://masutopedals.wordpress.com/2017/04/20/roland-tr-505-stuff/ There are many sources talking about having it done, without explaining how: http://www.burnkit2600.com/tr-505/#outputs http://gumielectronic.net/tr505.html The problem However, the modifications that are described share one […]
This drum machine from 1981 is a close relative of Roland CR-78 and TR-808. It has a couple shortcomings, such as no user editable sounds, a Snare Drum with a lot of tone (what is called “Snappy” on 808) but a lack of noise / high frequency content. It sounds more like a tom. Also […]
It seems Doepfer cut some corners when designing the MCV4 MIDI to CV interface. Firstly the MCV4’s gate voltage is to low to drive the Roland SH5 gate input. This can be remedied by opening up the interface to move a jumper, and then replacing the 9v power supply with a 12 volt one. After that the […]
A mid-80’s drum machine, modified for MIDI-controlled sound chip selection, circuit bending and pitch. Any MIDI sequencer or keyboard can be used. No changes are made to the exterior of the machine. The Kawai R-100 drum machine classic was modified using an Arduino Nano, the circuitbenders.co.uk “R-ROM Switcher” and a HC-SR08 board. The Nano reads incoming note […]