Projecttitel: RE-909


Startdate: 10/2020

Duedate: 02/2022

Updated: 13 Feb. 2024

Manufacture link:



Facebook Group:

Its an replica - not just another clone

Schematics and Service Notes:


a great way to save patterns:

RE-909 Rev1 (until 2022)

a rev2 PCB was released and fixed some Issues (marked in my list as affected version)

Buildguide and BOM for Rev1




the Powerswitch isn't listed in the BOM

for the 18V AC to DC PsU you can use a simple Switch.. 

but in case of 110V/230V look for the power rating of the switch and choose a dual switch for the best safety reason and law/regulation of your country.


this is perfect for all versions, since its a dual switch, which can switch the Neutral (N) and hot phase (P). (there's no power at the transformer, except from loaded capacitors)

ROCKER;DPST;Pos:2;OFF-ON;10A/250VAC;10A/28VDC;schwarz;Fehlen ROHS Hersteller: BULGIN Herstellersymbol: H8550VBBB

this is fine for the 18VAC PSU version, (since only one "cable" is switched off, there's still a risk of electrical shock while handling inside of the device)

links to the original files:

Christians Illustrated build guide part 1 ENGLISH   PSU

Christians Illustrated build guide part 2 ENGLISH Sequencer

Christians Illustrated build guide part 3 ENGLISH Mainboard

Christians Illustrated build guide RE-909_parts_orientation_and_tips_ENGLISH

Christians Illustrated build guide part 1 GERMAN

Christians Illustrated build guide part 2 GERMAN

Christians Illustrated build guide part 3 GERMAN

Christians Illustrated build guide RE-909_parts_orientation_and_tips_GERMAN

Buildguide and BOM for rev2.

also add the power switch as listed above in the "important note"





links to the original files:


For Rev1 and 2:

RE-909 case assembly guide (DE).pdf

RE-909 case assembly guide (EN).pdf

Installing the 909 Cartridge Reader.pdf

new: RE909 Transformer psu  (not for DC PSU) :RE-909_Transformer_PSU_BOM_MOUSER.pdf

R701-R704 =10K

R705 =1K

C701 =4.7uF/25V (better 35V/50V) 

Q701/Q702 = Sc945 - make sure to have HFE of minimum 280 (better more)

Zener Diode: use 1% as in above RE-909 transformer mouser BOM

Changelog (you can ignore this infos)

v.1.1added IC11 and D30, D31, D33 to ORDERING
v.1.2added info from christian about cabling
v.1.3added gnd build notes from Christian, fixed an amount value
v.1.4changed electrolytic capacitor in safety psu from 25V to 35V.

because its standard to have at AC Rectifier a safety range of multiplier 1.5 - 2

(for example an 18VAC is able to give after the rectifier a 28V-29V DC voltage.

regards Patrick (big grin)

v.1.5added extra alternative options for 10k trimmers (clap)
v.1.6fixed value in tape section.

new value R311: 820K (old value was 820R)

" Amp section "

fixed C143 voltage 47uF to 50V.

35V is fine too (comment Patrick)

v.1.7advisory added for snare drum fix.
v.1.8added info about cabling and errors in TR-909 service docs
v.1.9fixed values in high tom, C95 and C97 were reversed

new value C95: 100nF

new value C97: 15nF

(just swap both capacitors, old value was C95 15nF & C97 was 100nF)

IDIssueAFFECTED Version Fixdatefixed version

Snare Drum section - 


please download v.1.7 build documentation for details.

Service advisory: after building the snare you must place a jumper as shown in the pic below, this is shown without parts placed for clarify

bigger picture from me - easier to find the place..

17.Dec.20201.9 build guide
2C95/c97 Tom sectionRev.1swap both against each other17 Dec. 20201.9 buid guide

if you‘re using the Safety PSU do not connect pin 27 and pin 28 on the F3 cable, otherwise you‘ll create a ground loop.

17.dec. 20201.9 build guide

PSU - wrong routing

→ affects the memory


change the 5.6V zener as shown here:

17.Dec. 2020
          • not released - not Confirmed
5Noise floor - crosstalkREV.1

from FB RE-909 group:

"Hello! Just wanted to share some good news about noise and crosstalk issues on RE-909. Pictured below is a Roland TR-909 factory mod with a wire that seems to reinforce grounding between C151 styrofoam cap in the hihat low pass filter and the common analog ground track where R236 is also attached. By doing the same mod in RE-909, pictured below also in the bottom of the board, cymbals crosstalk and digital noise leak into the hihats channel is eliminated, which fixes the last remaining issue in my build. I used a thick grounding wire to connect the lower pin of C151 to the double hole in the common ground track next to R236. This fix works perfectly on traffo PSU but I can’t guarantee it works on safe PSU (and preliminary tests show it doesn’t) because of the difference in ground routing. Otherwise, enjoy your digital noise-free, crosstalk-free RE-909!"

6Gate rev1-2in case you hear the Gate signal of the SD in BD - you can try to connect a 1uF polar cap**  between GND and Trigger.  Measure with an scope to find the best value - maybe 470/680/820nF is fine too - or less.15.may 2022

was posted in the RE-909 FB group omg 10. may 2022

not tested by me, but confirmed by other people

7MIDI BUGrev.1 and 2

there's a failure in MIDI section



8Noise MODrev.1

only for rev.1 pcbs:

as described in the rev.2 guide, is there a extra trimmer for  the noise,

for rev.1 pcbs you should be able to cut a trace between 2 resistors and install a trimmer 

9jack IOrev1

only needed in rev.1 (rev2 still has this fix) 




You can use the MTA100 system from TE connectivity for example or Molex Style Connectors with a pitch of 2.54mm

2noisy/hissmake sure to solder the potentiometer at all pins to have the correct ground - (the ground flow thru the outside pins / it act like a trace/bridge) 

measure the transistor HFE value for the switchboard Q604 - a gain of 350 should be fine.

otherwise it can happen that MIDI OUT doesn't work.

you can also mod the MIDI Out :


select the * S* Transistors to the same HFE to get a balanced gain on all voices.

check the schematics for more details, all are 603/945P Transistors

q12 in Bassdrum

q51 in snaredrum

q20 in Low Tom

q27 in Mid Tom

q58 in High Tom

Q71 in Crash

Q85 in HH

Q65 in Rimshot

Q37 in Handclap

Q33 Tom Noise - should be ignored or just use the same hfe as above

5DAC assembly

use few millimeters height paper to get a correct alignment:


"RE-909 MOD KIT" Build Guide|Jun.pdf