MATRIXSYNTH: Roland TR77 Rhythm Machine


Monday, March 16, 2009

Roland TR77 Rhythm Machine

via this auction
"Roland TR77 Rhythm synth.
The Roland Rhythm 77 drum machine was Roland's first product (formerly Ace electronics) - released in 1972. It is actually an updated and relabelled Rhythm Ace FR-8L.

It was one of a trio of drum machines released by Roland that year, offering features intermediate between those of Rhythm 33 (TR-33) and Rhythm 55 (TR-55).

It comes in a flat wooden case with a metal base and has a holding for scorebooks - was dedicated to put at top of an organ for rhythm accompaniment.

General Product Information:
Contents
* 1 Rhythms:
* 2 Instruments:
* 3 Some technical inside:
* 4 External Sync

Rhythms:
· Latin: rhumba, beguine, cha-cha, mambo, samba 1&2, bossa nova, baion, bolero, tango
· Rock: rock'n'roll 1&2, slow rock, ballad, western, march, jazz waltz, waltz, cancel
· 2beat & 4beat: bass drum, snare, fox trot, swing, parade, shuffle

Instruments:
Bass drum, snare drum, lo conga, low bongo, high bongo, rim shot, maracas, high hat, cymbal, tambourine, guiro, cow bell. Rim are used for metronome, too.
has a little mixer for: bass drum, snare drum, guiro, high hats.
has a tempo & volume fader; and a fade-out option : for start there's no button, it's a finger-sensitive touch-bar, supports double tempo.
the power switch is not a primary AC-switch.

Some technical inside:
There's no IC inside - only one VCA...
Left: transformer, rectifier, softstart.
Mid: master clock, 5 dividers, reloop & down-beat LED, diode matrix.
The 1st divider is connected to the tempo-up switsch for a 1:1 or 1:2 ratio, the 2nd ones for switching between the 4/4 and 3/4 clock - 1:2 or 1:3 ratio.
Right: the voice board, mixer & output stage. BD, LC, LB, HB, rim are passive circuits.
Bottom: the rhythm switches...
External Sync
There's a little possibility to use din-sync on this device.
Logic board: leftest transistor, on its right the base resistor, solder on lower pin the clock line. For start/stop - its like a pedal switch - just put a transistor serial into the male connector: gnd=emitter, top=collector, base=start/stop line.

Works best at 8 ppm clock, up-tempo off for best results. On up-tempo on the guiro & tambourine it sounds bad as they have a 2nd trigger input which they get from the 1st divider."

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