Sequential Drumtraks Drum Machine Repair

Today I'm investigating issues with a Sequential Drumtraks. While it is making sounds, the display is glitching out and the control functions are not working. In the end it was only incidental I was able to get it working again, for reasons I don't fully understand. The same phenomenon happens with my Drumulator, that's how I knew what to check for. It's my hope posting this video, that someone more knowledgable will be able to comment about this phenomenon.

This video is posted for general information about my experiences. Always observe safety working on electronics, and never tinker around inside power supplies without first unplugging the power cord. If you're not sure about anything, there's no shame in taking your instrument to a qualified service technician.

Since filming the video, I've discovered the batteries are still made in Japan. Also, the numbers on the battery may or may not necessarily be a date code. My new battery says 2132, so maybe it was made in 2021? Since the manufacture date and date installed may differ by a couple of years, I now write a date on the battery with a sharpie when I install it.

Timestamps
0:00 Intro + Symptoms
0:28 Power Supply investigation
2:10 Battery
2:28 Data Bus Check
4:08 About Cleaning IC pins
4:28 Last ditch effort and suddenly it's working???
5:38 Short demo

I design analog Eurorack modules, check my Reverb store for availability.

Pro VCF Eurorack Filter First Look [Demo #1]

The Pro VCF is a faithful adaptation of a well-known 4-pole synthesizer filter in Eurorack.
The core of this design lies an Alfa AS3320 filter chip based on the original Curtis.
Let's put the Pro VCF through some paces.

Timestamps
0:00 Opening
0:23 Intro
1:01 Audio
0:19 Features
1:49 Audio
2:04 Input: analog PWM, Saw (Pittsburgh Synth Box)
2:43 Input: Digital Wavetable (E352) (PPG anyone?)
3:22 FM of Cutoff

More info at Modular Grid
Now available in my Reverb Store.
Audio recorded direct to Tascam DR-05.
No added effects.

Sequencing - Arturia Beatstep Pro Pitch CV + gate

Announcing the Pro VCF Eurorack Module

Coming next week: the Pro VCF.
The Pro VCF is a faithful adaptation of a well-known 4-pole synthesizer filter in Eurorack.
The core of this design lies an Alfa AS3320 filter chip based on the original Curtis. Countless synthesizers used the 3320: Sequential Pro One, Prophet 5 rev 3, Drumtraks, Crumar Trilogy, Stratus, Elka Synthex, some Fairlight CMI, Linndrum, Oberheim OB-8, OB-Xa, PPG Wave 2
At full resonance the Pro VCF can self-oscillate.

FEATURES
Two selectable filter slopes: original 24 db/oct, and 12 db/oct.
Two voltage controlled input jacks for frequency CUTOFF w/ signal attenuators.
A voltage controlled input jack for RESONANCE w/ a signal attenuator.
Two signal input jacks w/ individual attenuators. At full clockwise, these inputs can overdrive the filter from most eurorack oscillators and audio sources.

More details at Modular Grid

Linndrum Classic Drum Machine Quick Demo

This Linndrum w/ JL Cooper MIDI is currently for sale on Reverb. In this video I do a quick run through of the sounds on this Linndrum. First a quick overview, then single drum sounds, then some fun drum pattern programming.