First make sure that you have all the correct parts, pay special attention to the lead distance, these can be 2.5mm, 5mm and 7.5mm.
When you start soldering a section place all the parts that you need for that section on a piece of paper. some parts are hard to recognize, so write the part name on the paper next to the parts. If you use the excel file from the download section you can fill the cell with a color for the parts that you have placed on the board, an other color when they are soldered etc etc.

I advise you to start with the power section and test this part. Make sure this is working  as it should. Otherwise you might damage the other parts that you have already soldered. And be careful with the transformer and the mains current, you need to know how to handle these parts, you can get injured if you don't know what you are doing!
Afterwards you can start with the bass drum section. first solder diodes and resistors then capacitors and transistors then IC sockets and cable sockets. Build the MIDI section, output boards and noise section. Now test if everything is working well. When you have successfully tested these sections, continue building the 9090, voice by voice. Every time testing after populating a drum voice.
Building a voice also means wiring the potmeters.

when you have finished the entire project then you can put in the IC's.
When you solder the wires to the potmeters make sure that you have the correct length, not to long and not to short. I tried to safe money and used old ribbon cable from computer parts. This was a very bad idea, I had to change them and used 0.2mm³ wire instead.

Building a 9090 should not be the very first project that you do, practice your soldering skills on a couple of small projects or try the xoxbox (303 clone) like I did.

Information about the parts

The Mouser order list has been saved as a project and you can open it on the page. you need to enter the access ID: 9e4364d05b.
Or you can go to:
Then you need to save it as your own project.

I have ordered the parts from Mouser, Reichelt and Nikko electronics and of course the PCB's from Trevor.
You can save money ordering from a few supliers instead of just one.

In the alternative column you will find the name of the original parts of the 909. If you do not find them you can use the ones in the "name" column.

If you are going to use the original transistors, (these are in the synthage kit!!) you will need to bend the legs of those transistors because the Trevor Page boards are designed for the BC549 and BC559 ones. on the introspective group you will find the necessary pics how to bend the leads

click on the pictures below to enlarge them. The pics show you how to bend the leads of the original Roland tr-909 parts

2SA 1115

Not only do you need to bend the legs, You'll also need to place in a 180° position compared with how you would normally place the BC transistor. In other words you'll need to flip the transistor an place the flat side (text) facing the round part of the D shaped printing on the board.
SA 1115 bent leads    2SA 1115 bent leads 2  

2SC 2603

Not only do you need to bend the legs, You'll also need to place in a 180° position compared with how you would normally place the BC transistor. In other words you'll need to flip the transistor an place the flat side (text) facing the round part of the D shaped printing on the board.
2603 bent leads    2603 bent leads 2  

2SA 798 G

The original TR909 works with 2SA 798 transistors in the handclap, hihat and cymbal sections. The 9090 boards are designed to replase these rare parts with pairs of BC 559 transistors. If you are using the original 2SA 798 transistors, you'll need to bend the legs as shown in the pictures below.
On the pictures of my built 9090 in the handclap, hihat and cymbal sections 1115 transistors, in pairs, are used to replace the 2SA 798's.

parts of the 9090 boards

List notes

  1. Polyester capacitors are recommended for most non-polarised capacitors. Since PCB space is constrained, minature polyester / polyester film capacitors are recommended.

  2. Where electrolytic capacitors are used, be sure to use parts with sufficient voltage rating, particuarly those which are connected across power supply rails (use 16V minimum).Voltage ratings of the various electrolytics used in the prototype were typically:  0.47uF @ 50V   10uF@ 63V ... and so on.

  3. All resistors are 5% tolerance or better, except for those stated as 1%

  4.  For potentiometers: "A" indicates LOGARITHMIC. "B" indicates LINEAR.

  5. For most 100pf, 220pf etc. capacitors, Wima FKC3 series polycarbonate types were used.

  6. Polyester capacitors were used in place of some electrolytics in the prototype, particularly in the tom drum circuits.

  7. There are two instances of C173. This designator has been used twice in error.

  8. Use ZTX1051A as replacement for the two 2SD1469 transistors used in Snare Drum. A number of transistors were tried in place of the 2SD1469; ZTX1051A worked the best.  These transistors are available from Rapid Electronics in the UK.

  9. No MIX OUT components in this section are mounted to the PCB. Are mounted directly to sockets. (For resistors under "Output Sockets and associated circuitry")

  10. Long-leaded capacitors to allow mounting directly to jack socket terminals (For capacitors under "Output Sockets and associated circuitry")

  11. The original TR909 boards were designed for two 8 pin IC's (IC12 and IC13). The Trevor Page 9090 boards are designed for one 14 pin IC to replace the two 8 pin IC's. Thus you need to use the TL074 in this case.

Bass drum


quantiy   name alternative designator
1 c 0.1uF   C10
1 c 0.33uF   C14
2 c 0.47uF   C2 C3
2 c 100pF   C9 C51
2 c 10uF   C17 C174
1 c 2n2F   C21
3 c 33nF   C11 C15 C22
1 c 1uF   C18
1 c 3n3F   C8
1 c 4n7F   C12
1 c 68nF   C13
1 c 6n8F   C1
9 d 1N4148 1SS133 D1 D10 D11 D12 D2 D3 D5 D8 D9
6 q BC549 2SC2603F Q12 Q15 Q4 Q7 Q8 Q9
6 q BC559 2SA1115-F Q10 Q11 Q13 Q14 Q2 Q5
1 r 1K   R11  
14 r 100K   R13 R19 R20 R25 R29 R33 R47 R48 R49 R50 R66 R9 R45 R46
4 r 10K   R17 R37 R55 R59
1 r 12K   R3
1 r 150K   R27
1 r 1K8   R58
2 r 1M   R61 R62
8 r 22K   R1 R16 R2 R26 R4 R43 R51 R56
4 r 2K2   R12 R52 R53 R64
1 r 3K3   R28
2 r 330K   R44 R5
1 r 330R   R21
1 r 39K   R22
4 r 470K   R38 R39 R40 R57
7 r 47K   R10 R24 R35 R42 R6 R63
2 r 47R   R23 R36
5 r 4K7   R18 R34 R60 R7 R8
1 r 6K8   R65
1 u TL074 M5218A U2
1 u TL072  M5218A U3
1 vr 470RB    VR2  via J3
1 vr 100KA    VR3 via J3
1 vr 1MA    VR4 via J4
1 vr 100KB    VR5 via J4
1 vr 10KB   VR6  via J39 
1 vr 47KB    VR7  via J38
1 vr 10KB    VR8 via J2

Snare drum


quantity   name alternative designator
1 c 100pF  C49
2 c 0.47uF    C40, C42
1 c 100nF (poly)   C43
3 c 10nF  C30 C31 C33
1 c 10pF  C36
2 c 10uF    C34 C35
1 c 15nF    C32
1 c 220pF    C38
1 c 22nF    C26
2 c 2n2F    C27 C28
1 c 3n3F    C24
1 c 470pF    C41
1 c 47nF    C39
1 c 4n7F    C45
2 c 6n8F    C29 C44
14 d 1N4148  1SS133 D13 D14 D15 D16 D18 D19 D20
D21 D22 D23 D24 D25 D26 D27
1 d 18V ZENER   D17
2 q 2SD1469    Q16 Q20 
8 q BC549  2SC2603F Q17 Q19 Q21 Q22 Q23 Q25 Q26 Q27
3 q BC559  2SA1115-F Q18 Q24 Q28
18 r 100K   R100 R105 R107 R111 R123 R125
R126 R127 R130 R68 R69 R79 R80 R82 R83 R84
R88 R93
1 r 100R    R101
12 r 10K    R104 R108 R109 R113 R118 R129 R131 R67 R86
R91 R94 R99
2 r 1K    R110 R132
1 r 1K5    R116
3 r 1M    R102 R124 R128
6 r 220K    R120 R71 R76 R90 R96 R97
8 r 22K    R103 R117 R121 R122 R135 R72 R73 R98
2 r 2K2    R112 R87
1 r 3K3    R106
1 r 470K    R70
5 r 47K  R77 R81 R85 R92 R95
4 r 47R    R114 R115 R75 R89
2 r 4K7    R119 R74
1 r 6K8    R78
6 u TL072  M5218A U10 U4 U5 U6 U7 U9
1 u 4069UB    U8
1 vr 470KB    VR10 via J7
1 vr 10KB    VR11  via J7
1 vr 47KB    VR12  via J7 
1 vr 10KB    VR9  via J6


Low Tom


quantity name alternative designator
1 c 0.22uF   C55 
2 c 0.68uF   C52 C59
1 c 100nF (poly)   C47
1 c 10nF    C54
4 c 10uF    C61 C63 C66 C67
1 c 12nF  10nF C58
1 c 1nF    C173
1 c 22nF    C57
1 c 33nF    C50
1 c 47nF    C48
1 c 56nF    C46
16 d 1N4148  1SS133 D29 D30 D31 D32 D33 D34 D38 D39 D40 D41 D42 D44 D45 D46 D47 
1 d 18V ZENER    D36
8 q BC549  2SC2603F Q29 Q30 Q31 Q32 Q33 Q34 Q35 Q37
2 q BC559  2SA1115-F Q36 Q38
17 r 100K   R148 R153 R154 R155 R156 R159 R166 R174 R176 R178 R179 R182 R183 R189 R191 R192 R193
2 r 100R    R181 R188
13 r 10K   R136 R145 R146 R149 R157 R165 R168 R171 R177 R184 R187 R190 R180
3 r 1K    R147 R152 R160
4 r 1M    R150 R164 R167 R169
3 r 220K    R142 R143 R173
3 r 22K    R185 R186 R200
3 r 2K2    R139 R141 R163
1 r 2M2    R137
3 r 470K    R134 R140 R144
3 r 47K  56K (R175) R151 R158 R175
3 r 47R    R133 R162 R172
1 r 4K7    R170
1 r 56K    R161
1 r 68K    R138
5 u TL072  M5218A U11 U12 U13 U15 U16
1 u 4069UB    U14
1 vr 10KB    VR13 via J10 
1 vr 470KB    VR14 via J14 
1 vr 47KB    VR15  via J14 

Mid Tom


quantity   name alternative designator
1 c 0.15uF    C77 
2 c 0.47uF   C74 C81
1 c 100nF (poly)   C69
1 c 10nF    C80
4 c 10uF    C83 C85 C86 C88
1 c 18nF    C79
1 c 1nF    C87
1 c 27nF  33nF C72
1 c 47nF    C70
1 c 56nF  47nF C68
1 c 6n8F    C75
16 d 1N4148 1SS133 D103 D48 D49 D50 D51 D56 D59 D60
D61 D62 D63 D64 D66 D68 D69 D70
1 d 18V ZENER   D58
8 q BC549  2SC2603F Q39 Q40 Q41 Q42 Q43 Q45 Q46 Q48
2 q BC559  2SA1115-F Q47 Q50
17 r 100K   R212 R218 R219 R221 R222 R223
R235 R248 R250 R252 R253 R254
R258 R259 R269 R270 R271
2 r 100R    R257 R264
13 r 10K   R198 R209 R210 R213 R225 R236
R238 R245 R251 R256 R260 R263 R265
3 r 1K    R211 R217 R232
4 r 1M    R214 R234 R239 R243
3 r 220K    R206 R207 R247
3 r 22K    R261 R262 R272
3 r 2K2    R201 R205 R231
1 r 2M2    R203
3 r 470K    R199 R202 R208
3 r 47K  39K (R216) R216 R226 R249
3 r 47R    R197 R230 R242
1 r 4K7    R241
1 r 56K    R229
1 r 68K    R204 
5 u TL072  M5218A U18 U19 U20 U22 U23
2 u 4069UB    U21
1 vr 10KB    VR16 via J15
1 vr 470KB    VR17 via J16
1 vr 47KB    VR18 via J16

Hi Tom


quantity   name alternative designator
2 c 47nF   C89 C99
1 c 0.15uF    C95
2 c 0.47uF    C100 C92
4 c 10uF    C93 C101 C103 C104 
1 c 100nF (poly)   C90
1 c 15nF    C96
1 c 22nF    C91
1 c 1nF    C106
1 c 5n6F  4n7F C94
1 c 8n2F  10F C97
16 d 1N4148 1SS133 D71 D72 D73 D74 D77 D79 D80 D81
D82 D83 D84 D85 D86 D87 D88 D89 
1 d 18V ZENER   D78
8 q BC549  2SC2603F Q51 Q52 Q53 Q54 Q55 Q56 Q57 Q59
2 q BC559 2SA1115-F Q58 Q60
17 r 100K   R286 R288 R290 R293 R294 R295
R302 R311 R312 R314 R317 R318
R323  R324 R332 R333 R336
2 r 100R   R322 R329
13 r 10K   R274 R283 R284 R287 R296 R303
R305 R313 R316 R325 R328 R330 R334
3 r 1K   R285 R292 R298
4 r 1M   R276 R301 R306 R310
3 r 220K   R280 R281 R331
3 r 22K   R319 R326 R327
3 r 2K2   R279 R300 R308
1 r 2M2   R275
3 r 470K   R277 R282 R304
3 r 47K 39K (R315) R291 R297 R315
3 r 47R   R273 R309 R335
1 r 4K7   R321
1 r 56K   R299
1 r 68K   R278
5 u TL072 M5218A U24 U25 U28 U29 U30
1 u 4069UB   U26
1 vr 10KB    VR19 via J22
1 vr 470KB    VR20 via J24
1 vr 47KB  VR21  via J24


Rim shot handclap


quantity   name alternative designator
1 c 1nF   C107
4 c 10nF   C111 C112 C114 C115
1 c 18nF 15nF C110
1 c 220pF   C123
2 c 27nF 22nF C117 C118
1 c 47nF   C113
2 c 4n7F   C108 C109
4 d 1N4148 1SS133 D90 D91 D92 D93
2 q BC549 2SC2603F Q61 Q63
1 q BC559  2SA1115-F Q62
2 r 10K   R341 R353
3 r 12K   R345 R346 R347
2 r 1M   R340 R368
1 r 220K   R344
4 r 22K   R337 R343 R352 R355
3 r 2K2 3K3 (R349) R338 R349 R351
1 r 2K7   R364
1 r 330K   R369
1 r 3K3   R348
2 r 470K   R350 R365
1 r 47K   R342
3 r 4K7   R339 R354 R371
1 r 680R   R367
3 u TL072  M5218A U33 U34 U35
1 vr 100KB    VR22 via J28

quantity   name alternative designator
3 c 0.47uF    C121 C131 C135
2 c 100nF (poly)   C124 C134
3 c 1nF    C116 C125 C130
2 c 10uF    C128 C132
1 c 220pF    C127
1 c 22nF    C126
1 c 27nF  22nF C122
2 c 4n7F    C119 C120
4 d 1N4148  1SS133 D94 D95 D96 D97
3 q BC549  2SC2603F Q64 Q67 Q69
3 q BC559  Q65-66  2SA798 (matched pair)
Q68       2SA1115-F
Q65 Q66 Q68
1 r 100K    R375
5 r 10K    R370 R387 R396 R400 R401
1 r 150K    R386
2 r 15K    R372 R379
3 r 1K    R377 R389 R390
2 r 1M    R376 R384
4 r 22K    R383 R397 R398 R399
1 r 2K2    R357
1 r 2K7    R393
1 r 330R    R380
1 r 39K    R388
1 r 3K3    R391
2 r 470K    R374 R394
3 r 47K    R356 R366 R395
1 r 47R    R402
4 r 4K7    R378 R392 R403 R405
1 r 5K6    R373
2 r 68K    R382 R381
2 r 82K    R385 R404
2 u TL072  M5218A U36 U40
1 u CA3080    U38
1 u LM2901    U39
1 vr 50KB    VR23 via J28
1 vr 10KB (trim)   VR1 




quantity   name alternative designator
1 c 0.01uF C152
1 c 100pF   C150
2 c 10uF    C143, C146
1 c 1n2F   C141
2 c 1nF   C140 C142
1 c 1uF   C163
1 c 2n7F   C139
1 c 390pF   C138
1 c 470pF   C164
4 d 1N4148  1SS133 D101 D102 D98 D99
5 q BC549 2SC2603F Q70 Q71 Q72 Q74 Q91
3 q BC559 Q80-73  2SA798 (matched pair)
Q90       2SA1115-F
Q73 Q80 Q90
2 r 100K   R425 R466
1 r 100R   R434
9 r 10K   R415 R417 R422 R436 R463 R467
R473 R475 R476
1 r 10K 1%   R525
1 r 150R   R411
1 r 160K 1%   R528
1 r 20K 1%   R526
1 r 220K    R423
4 r 22K   R435 R454 R468 R481
1 r 22R   R410
2 r 2K2   R421 R464
1 r 33K   R469
1 r 40K2 1%   R527
1 r 47K   R420
1 r 4K7   R406
1 r 5K1 1%    R524
4 r 5K6   R414 R416 R418 R419
1 r 6K8   R470
1 r 80K6 1%    R529
2 u TL072 M5218A U42 U52
1 u 40174   U44
1 u 4040   U48
1 u 27C256   U49 
1 u 4520   U54
1 u 4011UB   U61 
1 u 4013   U64
1 vr 47KB   VR24 via J33 
1 vr 100KB    VR25 via J33
1 vr 1MA   VR26 via J33
1 vr 10KB   VR31 via J34



quantity   name alternative designator
2 c 100pF   C170 C171
7 c 10uF   C149 C155 C156 C160 C165 C172
2 c 1n2F   C136 C137
4 c 1nF   C144 C145 C154 C157
2 c 2n7F    C151 C153
2 c 390pF   C158 C159
2 c 470pF   C168 C169
6 q BC549 2SC2603F Q75 Q76 Q81 Q83 Q84 Q85
4 q BC559 Q77-78  2SA798 (matched pair)
Q79-82  2SA798 (matched pair)
Q77 Q78 Q79 Q82
2 r 100K   R480 R482
2 r 100R   R428 R441
6 r 10K   R426 R427 R442 R443 R477 R479
4 r 10K 1%   R501 R506 R513 R519
4 r 160K 1%   R502 R510 R515 R523
4 r 20K 1%   R503 R508 R514 R521
2 r 220R   R431 R444
2 r 22K   R452 R453
2 r 22R   R432 R449
1 r 270K   R448
4 r 2K2   R439 R440 R445 R460
4 r 40K2 1%   R504 R509 R516 R520
1 r 470K   R430
2 r 47K   R424 R429
2 r 4K7   R407 R433
4 r 5K1 1%    R500 R507 R512 R518
8 r 5K6   R408 R409 R412 R413 R437 R438
R446 R447
2 r 6K8   R478 R483
4 r 80K6 1%   R505 R511 R517 R522
3 u TL072  M5218A U45 U47 U50 (U52)
2 u 40174 U51 U53
1 u 27C256   U55
1 u 27C256   U56
2 u 4040   U58 U60
1 u 4520   U59
2 u 4011UB   U63 U66
2 u 4013   U62 U65
1 vr 10KB    VR28 via J35
1 vr 47KB    VR27  via J35 
1 vr 10KB    VR30 via J37
1 vr 47KB    VR29 via J37

Midi interface


quantity   name alternative designator
3 c 1nF    C102 C105 C98
2 c 10uF    C162, C166
2 c 100nF (cer)   C167, C161
2 c 33pF    C147, C148 
1 d 1N4148  1SS133 D100
1 d MIDI LED   LED1 
1 d Power LED   LED2
3 q BC559  2SA1115-F Q86 Q87 Q88
1 q BC549 2SC2603F Q89
1 r 4K7    R289
1 r 100K   R462
1 r 10K 1%   R360
1 r 160K 1%    R359
2 r 1K   R451 R457
1 r 20K 1%   R362
3 r 220R    R471 R472 R474
2 r 22K   R455 R458
2 r 330R   R307 R320
1 r 3K9   R459
1 r 40K2 1%    R363
3 r 47K   R450 R456 R465
1 r 5K1 1%    R358
1 r 680R   R461
1 r 80K6 1%   R361
1 sw Pushswitch   SW1
2 u 4051   U27 U32
1 u TL074 M5218A U31
3 u 40174   U37 U43 U41
1 u PIC16F84   U46
1 u 6N136   U57
1 xtal 4MHz crystal   XTAL1

Noise circuit


quantity   name alternative designator  
1 c 10uF    C82  Noise circuit
1 c 100nF (cer)   C71  Noise circuit
1 c 100pF    C84 Noise circuit
1 c 47nF    C73 Noise circuit
4 c 4n7F    C62 C64 C65 C78 Noise circuit
1 c 4u7F   C76 Noise circuit
8 d 1N4148  1SS133 D53 D54 D55 D57 D65 D67 D75 D76 Noise circuit
2 q BC549  2SC2603F Q44 Q49 Noise circuit
4 r 100K    R215 R237 R244 R246 Noise circuit
5 r 10K    R194 R228 R233 R255 R267 Noise circuit
1 r 1K    R227 Noise circuit
1 r 220K    R196 Noise circuit
3 r 22K    R195 R224 R266 Noise circuit
1 r 33K    R268 Noise circuit
1 r 47K    R220 Noise circuit
1 r 47R    R240 Noise circuit
1 u TL072  M5218A U17 Noise circuit
2 u 4006   U68 U69 Noise circuit
1 u 4070   U67 Noise circuit



quantity   name alternative designator
5 c 10uF    C23 C6 C7 C20 C25
2 c 1uF    C4 C5
1 c 47uF/35V   C16
3 d 1N4148 1SS133 D4 D6 D7
2 q 2SC2878   Q1 Q3
1 q BC559 2SA1115-F Q6
1 r 10K   R31
2 r 1K   R30 R32
2 r 22K   R14 R15
1 r 470K   R41
1 r 4K7   R54
1 u TL072 M5218A U1
1 vr 47KB    VR32 via J5

Power supply

The transformer, for the power supply, that I used, is not the best type for audio applications. It is better to use a Ring transformer.
On the pictures I am testing the voltages with the bass section resistors and caps already soldered on the board. If you test the voltages you shoud have a load on the -15V (7915 voltage regulator). You can do that with a 470 Ohm resitor between the -15V and 0V leg of the connector where I attached the Voltmeter.
The power supply I used, is a 24VA 15V - 0 - 15V transformer, this is enough to supply the 9090 boards. If you also would like to prepare for the soon to be released sequencer user interface and Midibox LPC core, then a 30VA transformer will be better, 24VA probably won't do the job.

quantity   name alternative designator
2 c 2200uF    C37, C19
3 c 100nF (cer)   C53, C56, C60
3 d 1N4001    D28 D35 D43
1 d Bridge rect   BR1
1 q 7915   REG1 
1 q 7805   REG2
1 q 7815   REG3
2 misc FUSE   CP1, CP2
1 misc 15V - 0 - 15V mains transformer    

Output sockets


quantity   name alternative designator
10 r 1K   R600 R603 R606 R609 R612 R615
R618 R621 R624 R627
2 r 2K2   mix out
4 r 8K2    R607 R614 R623 R628
3 r 10K    R626 + 2 ON MIX OUT
11 r 12K   R601 R602 R604 R605 R610 R611
R616 R617 R619 R620 R625
4 r 15K   R608 R613 R622 R629
12 c 10nF (long leg)   C600 C601 C602 C603 C604 C605
C606 C607 C608 C609 + 2 ON MIX OUT
12 misc 1/4" jack socket, mono