bC8 nano synth PT4 - 6

YouTube via ChimSyn.

Prior videos and more posts here.

Roland 80017a

via this auction for the 80017a

"Problems Typically Solved by Replacing the Failed 80017a Chip Include:

* Erratic or sudden loud noise from synthesizer output, particularly after 10 minutes of powering up.
* Note hang-ups or long sustain.
* One synth voice will not respond to filter or amplifier changes.
* Unstable operation.
* Juno-106 or MKS-30: Notes will not play, most typically every 6th note will not play due to failed 80017a chip.
* GR-700: One particular voice or string will not sound, "D" string, "A" string etc.

The sound of the failure will change depending on which part of the circuit is not working: the VCF or VCA for example. The above example is provided to illustrate one type of failure. Your synth may have different symptoms as listed above. About the 80017a VCA/VCF chip:

The 80017a chip was a real workhorse for Roland synthesizer engineers in the early 1980s. This one chip contained both the classic, driving -24 dB voltage controlled low-pass filter with a smooth voltage controlled amplifier. By placing all the components on one chip, Roland was able to keep the classic sound of their analog synthesizers across various products, with low production costs. Almost immediately Roland knew they had a problem on their hands, and changed production methods.

When these chips fail, sometimes voice will stop working completely. On a keyboard synth, this shows up as every sixth voice not working. On a GR-700 guitar synthesizer, this shows up as one string’s synthesizer voice failing. But the chips may not fail completely, resulting in a lack of control over the filter quality for one voice, or by sudden, loud erratic sounds from the synthesizer. The only solution to these problems is to replace the existing 80017a with a new chip.

This chip is from lot 50, produced after Roland solved the manufacturing problems. Probably 20 years after the original production date, this chip is still working well without failure."

You can find scans for the following all via the auction here
Juno-106 Service Manual
Roland Service Note
MKS-30 Schematic
Juno-106 Failed Chip Test Procedure
Juno-106 Calibration
GR-700 Calibration

Moog Memorymoog Plus

images via this auction
"The memorymoog + is the only one capable of taking a MIDI retrofit, and it also has more stable oscillator control. The version can be checked in the AUTOTUNE feature. The Memorymoog is like having six Minimoogs stacked in one! Features include VCO syncing, sample and hold, and separate filters for each voice! It also has a unison mode for a fat 18 oscillator monophonic bass and lead. And as its name would suggest it has memory storage, 100 patches!"

KORG MS20

images via this auction
"It is the original factory built 240V AU/UK/European version with original moldered Australian plug and can safety be used in all countries with 230/240V such as AU.UK and Europe. This is a huge advantage to buying one of the 100V MS-20's from Japan

Originally, the filters used Korg's proprietary KORG-35 chip. Later, the filters were redesigned to use off-the-shelf LM13600 OTAs. MS-20 fitted with LM13600 filters have a small daughter board. This one here has the later filter (the small screw above the VCA graphic on the outside it's a newer filter, if it has no screw it's a korg35. That screw is what holds the daughter board for the newer filter. )"

Synthesizer Magazin #10

via sequencer.de

German print only.

susm - my diy synthesizer (prototype)

YouTube via mytoube2008. Livewire type knobs.
"here my synthesizer prototype.

features:
2 x lfo
2 x vco
lp / hp / bp filter
vca with 2 x lfo
routingmatrix (everything to everything)

all oscilators got square and triangle out and have also a seperat output for all waveforms, so you can use together with a modular system.

mainoutput goes thru filter and vca which are both bypass abled.

--- reverb added ---"

Analog Synthesizer DIY Test Teil II

YouTube via Redled72

tr-606 mod

YouTube via analoguesynth

MaxMSP clicks for the modular synth.

YouTube via dkimcg
"I used the PlanB Model 17, Model 10, and the Model 26 to create syncopated rhythms based on a click that Max/MSP was outputting via the MOTU 828 MK2. The Triple Timer is excellent for making triggers/pulses out of any incoming voltage. It doesn't have to be an envelope, so it's great for making the Cyclotron the master clock. You can create triplets from the slower notes with the M28, but it can get a bit messy and hectic unless the beat is a steady 1/4 or 1/2 notes.

This patch in max is one from a little while ago where I was testing out the new meter system in Max5 and the click~ object. There's no midi involved, just clicks and the modular processing the click and making new triggers and envelopes from that and the modulators.

There are samples though. two tracks of them, in Max."

Crumar Spirit analog synth

YouTube via buchla300

"Great little synth I just got back from being repaired by James Walker at Synth Repair Services. Don't have much experience of it, so just me noodling. I like it towards the end (after 5 minutes) where I add S&H to the filter. Very flexible with 2 filters and some great modulation possibilities and a pretty funky Arpeggiator." Odd note: this one sounds a bit like my Waldorf Pulse Plus.