Hardware Changes
There were several changes made to the TR-909 in its time of production:
| SERIAL # from | SECTION>SUBSECTION>>LOCATION | CHANGE |
| 370600 | Battery Compartment Lid | From rubber-made to metal-made |
| 381500 | Tape Sync >Filter & Amp >>Voicing Board
Bass Drum >ENV-3 >>Voicing Board |
C87 from 10pF to delete R306 from 4.7k to 47k R312 from 470k to 4.7M For optimizing waveforms coming from tape C9 from 0.22µF to 0.33µF For expanding the TUNE range |
| 393000 | RESET >>Power Supply Board |
D701 from RD6.8JB2 to
RD5.6JB2 Ensures reliable operation even at 20% below the nominal voltage |
| 415300 | RIM SHOT >OSC-3 >>Voicing Board HI-HAT >Amp >>Voicing Board RIM SHOT/TRIG OUT (TAPE SYNC) >>Voicing Board >>DIN Jack Board |
R417 from 12k to 3.3k For giving the voice more realistic sound
C134 from 10µF to 0.01µF For rolling off unnecessary lower Frequencies
From jumper wire to R495 1k R393 from 10k to 1M R392 from 22K to 1M Add C600 0.1µF between terminal No.30 and the ground (TRIG OUT jack – Hot ground). For preventing RIM SHOT signal from being induced onto TAPE SYNC signal which otherwise may cause glitches |
| 426700 | TOM NOISE >>Voicing Board |
C54 from 2.2nF to 4.7 nF R194 from 47k to 100k Emphasizes the attack of TOMs |
This site is NOT optimized for a certain crap