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 0.22F to 0.33F

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 10F to 0.01F

For rolling off unnecessary lower Frequencies

 


From jumper wire to R495 1k

R393 from 10k to 1M

R392 from 22K to 1M

Add C600 0.1F 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

 


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