Sequential Circuits Drumtraks repair, modification and maintenance.
- arps6000
- Dec 29, 2024
- 4 min read
Updated: Dec 30, 2024
This one came across the bench from the original owner, who bought it new back in the day from Kosmic Sound. Fault description was "heating up, then after 30 minutes, audio starts distorting" with an anecdotal from the owner, that since buying from new, it always seemed to run quite hot.
Upon opening, was greeted by this message from the past, still relevant today... but first lets take a look at this machine in the context of what was being released at the time.
Sequential circuits Drumtraks released in 1984, was ahead of its rivals of the time, with the ability to
program tempos and tempo changes,
levels of individual voices (in both live and record modes), and
and each instrument's pitch.
Notable features at the time of manufacture, which have attributed to its sought after status include
Analog sound generation: The DrumTraks uses 12-bit samples stored on EPROM chips, which are then processed through an analog 24 dB low-pass filter, giving it a unique, warm sound.
12-voice polyphony: The machine can play up to 12 simultaneous drum sounds, making it suitable for complex drum patterns.
MIDI compatibility: The DrumTraks is fully MIDI-equipped, allowing for easy integration with other MIDI devices and sequencers.
Programmable tuning and volume: Each of the 13 drum sounds has its own programmable tuning and volume controls, allowing for customization and flexibility.
Pattern and song storage: The DrumTraks can store up to 100 patterns and 100 songs, making it possible to create and save complex drum sequences.
Along with many synthesizers and drum machines that have achieved legendary status, the warm sounds of analogue processing, is what producers gravitated towards. Digital sampling technology had been introduced commercially to the studio via the Linn LM-1 and Oberheim DMX in 1980, and the E-mu Drumulator in 1983. These used digital sampling technology to store and play back pre-recorded drum sounds. The Drumtraks
generated sounds through analog synthesis, with each voice consisting of two analog oscillators, allowing for a depth of sound, beyond not just the digital processing drum machines of the era, but also other 80s analog drum machines, such as the Roland TR-808 - classic sounds vs the flexibility and superior programming of the Drumtraks.
"May peace prevail on earth".. first look upon opening is the straight forward, ergonomic design. Easy access for through hole component replacement, including the long discontinued 2-part tact switches, also used most notably in the E-mu Sp-1200. Clearly labelled EPROM chips for sounds, that can be swapped around.
First point of testing is the power PCB, with some of the components close to tolerance. Given age, I replace most of the components there, except one type. Despite being a common component, the modern replacements are not "Drop in" replacements - same form, only the specifications differ from manufacturer type.
A mechanical service and check is performed, where Im satisfied that all has been done to return the unit as close as possible back to a new state - without having to replace any expensive components. Now one last issue to pinpoint, and that to resolve the heat issue, as heat is a main factor that reduces the lifespan of electronics.. which can lead to an early grave, for vintage devices, with discontinued components.
..And this is the advantage of taking your equipment to a technical workshop. Knowing how things work and are put together, is a step above the aggregates approach to "checklist repairs", as a service manual will never be a "complete guide to repair." A design modification was performed, which resulted in less heat being generated.
Sound output and functionality was then tested, with no distortion and when returned to the owner, final word being after lengthy use (recall he had bought this Drumtraks new at the time) was that "its operating with far less heat generated and functions are a slight bit quicker to engage"
This was a minor repair fortunately, and as always, preventative maintenance is highly recommended for vintage devices, before it gets to this point. Whilst the cry of "it still works!" is heralded by many a vintage device owner, the smarter ones know that the majority of components have a "working tolerance" ie operating range, which deviates with use over the years. "Working" does not mean the circuit is healthy - a "working" unit can continue to operate, whilst close to tolerance components, continue to move towards failing. Failed components cannot be repaired, only replaced.
This Drumtraks was fortunate to have not suffered any further faults, a large part due to the owner utalising for live use - not in-situ, constantly powered on for hours/days at a time, in a studio.. Ive had a cursory look at anecdotal youtube and forum posts detailing Drumtraks faults/repairs and many do mention the heat generated, with several more faults described than this units.
Correct diagnosis, thorough repair and maintenance on the bench of a technical workshop, is the pathway to continued use of your vintage drum machines, for many decades to come.
