ARP_Omni_2480_Service_Manual电路图.pdf

《ARP_Omni_2480_Service_Manual电路图.pdf》由会员分享，可在线阅读，更多相关《ARP_Omni_2480_Service_Manual电路图.pdf（40页珍藏版）》请在收音机爱好者资料库上搜索。

1、 -. . .,:. tme OMNI Model 2480 . SERVICE MANUAL ARP INSTRUMENTS, INC. 320 Needham Street Newton, MA 02164 (617) 965- 9700 Document Number 90020000 February, 1977 ARP INSTRUMENTS, INC. THE INFORMATION CONTAINED HEREIN IS CONFIDENTIAL AND PROPRIETARY TO ARP INSTRUMENTS, INC. IT IS DISCLOSED TO YOU SOL

2、EY FOR PURPOSES OF INSTRUCTION AS TO OPERATION OF THE EQUIPMENT AND MAINTENANCE AS APPROPRIATE. IT IS NOT TO BE USED BY YOU FOR ANY OTHER PURPOSE, NOR IS IT TO BE DISCLOSED TO OTHERS WITHOUT THE EXPRESS PERMISSION OF ARP INSTRUMENTS, INC. RadioFans.CN 收音机爱 好者资料库 OMNI Model 2480 SERVICE MANUAL TABLE

3、OF CONTENTS 1. INTRODUCTION 1.1 Product Description 2 1.2 Specifications 2 1.3 Function Description 3 2. THEORY OF OPERATION 5 3. CIRCUIT DESCRIPTIONS 3.1 Upper Voicing Board 5 3.2 Lower Voicing Board 6 3.3 String Control Board 8 3.4 Synthesizer Control Board 9 3.5 Synthesizer Board 10 3.6 Phaser Bo

4、ard 10 3.7 Power Supply 11 4. ASSEMBLy/DiSASSEMBLy 12 5. GENERAL INFORMATION 12 6. CALIBRATIONS 13 7. SCHEMATICS 0, +1 OV 2. Trigger: Tini D Jack; 0, +10V pulse, 2 microsec. duration D. Foot Switch and Foot Pedal 1. Standard ARP accessories III. Miscellaneous A. Keyboard 1. 4 octave keyboard, split

5、for bass voices at one and a half octaves from low end B. Pedals 1. Filter control pedal for foot co1 of filter brightness . C. Sustain Switch 1. Foot switch works like sustain pedal on piano D. Materials 1. Aluminum chassis 2. Rigid high-density particle board base 3. Solid walnut end blocks 4. Gla

6、ss-epoxy circuit boards 5. Industrial-grade electronic components and controls E. Weight 1. 33 pounds 2 RadioFans.CN 收音机爱 好者资料库 3 2 16 17 r SYSTEM INTERFACING I r VCF CONTROL INPU1=S I SUSTAIN TRIG GATE FOOT SWITCH OUT ou ACCESSORY PEDAL 1.3 Function Description 1 Mix Control: Determines the balance

7、 of the string voices and the synthesizer voices. 2 LFO Speed: Varies the frequency of the Low Frequency Oscillator. 3 Master Volume: Determines overall volume of the mixed output. 4 Waveform Enhancement: Alters waveforms produced by the Omni to a hollow like (square) sound. 5 Chorus Phaser: Routes

8、the synthesizer output through the string sections phase shifters and reduces the phase shifters speed. (When de pressed the synthesizer output appears on the string output as well.) 6 Synthesizer 8, 4: Selects the synthesizer sec tions pitch ranges. 7 Synthes/er Bass 8, 16: Selects the synthe sizer

9、s bass voices and disables synthesizer 8 and 4 voices in bass range (first octave and a half). 8 ADSR Envelope Generator: Determines the attack and decay characteristics of the synthe sizer section. 9 VCF Frequency Slider: Sets the VCFs initial frequency cutoff point. 10 VCF Resonance Slider: Sets d

10、egree of VCF resonance (wow effect). 21 22 11 VCF ADSR Slider: synthesizer section. Determines brightness of 12 VCF LFO Slider: Determines depth of tremelo. 13 VCF Pedal and Accessory Slider: Determines range of external pedal or accessory. 14 Violin ranges. and Viola: Selects the string pitch 15 Ba

11、ss, Cello: Selects bass string pitch (low note priority, lowest octave and only). ranges a half 16 Attack: Determines attack of string section. 17 Release: Determines the final release time of string section (also effects synthesizer release). 18 Bass Volume: Determines bass volume synthesizer 16,8

12、and bass and cello. for 19 Sustain Foot Switch: Sustains all notes when foot switch is depressed (regardless of release slider settings). 20 Gate and Trigger Output Jacks: connect to other synthesizers. Used to 21 Accessory Jack: Connected to VCF control input so that VCF may be controlled by ex ter

13、nal sources such as the ARP Sequencer or Sample and Hold outputs, etc. for special effects. 22 Pedal Jack: Used to connect VCF filter pedal. 3 SIMPLIFIED OMNI BLOCK DIAGRAM 1- I 49 lines 1 line .rt.rL .rt.rL - MASTER TOP 12 lines GATEFREOUENCY WAVE STRING 4 -+-.rt.rL OCTAVE PHASER f- - 8 OSCILLATOR

14、CIRCUITSDIVIDERS SHAPERS VCA2.!.J.ines DIVIDER t tt 49 lines ,; BUS IKEYING r- RODS CIRCUITS 21 lines STRING AR MIX OUTPUT OUTPUT 0 8 M/X STRING SECTION ,-. BASS L.-.t. PRIORITY - 16 CIRCUIT -.:z:. I chorus switch BASS I L t r- I I I I L / VCF r- t I VCA t ADSR SYNTHESIZER SECTION I SYNTH ESIZER I O

15、UTPUT : I I SECTION 2 THEORY OF OPERATION SECTION 3 CIRCUIT DESCRIPTIONS The OMN Is tone generator circuitry consists of a master oscillator at 500 kHz., which drives a large scale integrated circuit top octave divider. The top octave divider produces the highest twelve tones in the instrument. Freq

16、uency dividers derive the remaining pitches from the top octave divider. The squarewave outputs of each divider are waveshaped to a sawtooth form (the waveform enhancement alters the waveshape to a differentiated squarewave). The tones from the waveform generator are fed to transistor gating arrays

17、which route the signal to the string section and the synthesizer section. The transis tor gating arrays are keyed on by an RC circuit connected to each key. The release time of each key (how long the note remains after a key release) is determined by the release capacitor on each gating input. The o

18、utputs of all the gating arrays are summed and routed to the string section and the synthesizer section. The string section consists of three parallel phase shifters which modulate the sawtooth waveforms from the gating circuits. The phaser outputs are processed through a Voltage Controlled Amplifie

19、r to control the attack characteristics. (The release is con trolled by the release capacitor on each gating circuit). The synthesizer section processes the gate outputs of the arrays through a Voltage Controlled Filter and Voltage Controlled Amplifier, both of which are controlled by an ADSR Envelo

20、pe Generator. The synthesizer output can be routed through the string section phasers when the Chorus Phaser Switch is selected. The speed of the phasers is reduced when the Chorus Phaser is selected. The outputs of the string section and the synthesizer section are summed together in the Mix Circui

21、try and routed to the output of the instrument. A separate synthesizer output is provided for stereo effects. 3.1 Upper Voicing Board GENERAL: The Upper Voicing Board contains the Master Oscillator, Top Octave Divider I.C., Frequency Dividers, Wave Shaping for tones C7 through C4, Keying Circuits fo

22、r keys 21 through 49 and six of the ten Gate Circuit /.C.s. The remaining Waveshaping, Keying Circuits and Gate I.C.s are located on the Lower Voicing Board. (Note: There are two schema tics for th is board.) 3.1.1 MASTER OSCI LLATOR AND TOP OCTAVE DIVIDER (Refer to Upper Voicing Schematic, sheet 1

23、of 2.) L1 and 01 produce a 0 to -15 volt sine wave at approximately 500KHz. The frequency of the oscilla tor can be varied by adjusting the core of the coil (externally accessible). Z1 buffers and squares the waveform from the Master Oscillator and supplies it to the Top Octave Divider, Z2. Z2 is a

24、LSI (Large Scale Integrated Circuit) divider which produces the highest octave (square waves) of the instrument (C6C7). 3.1.2 DIVIDER AND WAVE SHAPING CIRCUITS (Refer to Upper Voicing Schematic, sheet 1 of 2.) The square wave outputs from Z2 are supplied to the clock inputs of CD4520BE divider chips

25、 (Z3-Zl) which produce square waves for each key. The square wave outputs of the CD4520BEs areuffered by inverters Z9-Z16. o i Waveform converter and waveform enhancement The square waves Trom inverters Z9Z13 and from Z2 are differentiated by capacitors C17-C49 (values are selected for each frequenc

26、y). CR1 through CR41 clip the negative portion of the differentiated square wave resulting in sawtooth shaped waveforms. By altering 5 the DC bias (P6-7, Waveform Control Bus) some of as the inputs to the devices. Five of the arrays are the negative portion of the differentiated waveform is used for

27、 4 pitches and five for 8 pitches. Therefore, permitted to pass through diodes CR1-41 when the one key controls two gate chips at a time (4 and 8). Waveform Enhancement is selected resulting in a hollow type sound. The Upper Voicing Board contains three 4 gate arrays and three 8 arrays; the remainin

28、g arrays are on 3.1.3 KEY ING CI RCUITS the Lower Voicing Board. All of the arrays have the base pin (7) grounded. Each of the sawtooth wave (Refer to Upper Voicing Schematic, sheet 2 of 2.) forms are supplied to an emitter through a 100Kohm resistor (e.g. Tone G 4 is supplied through resistor Each

29、key contact (P7-5, P7-4, P7-3, etc.) is connected pack Z30 pins 5 and 6 to pin 12 of Z31.). Keying to a 22uf electrolytic capacitor through a 4700hm voltages (denoted by KV) are supplied to the emitters resistor. The capacitor is normally charged to 0 volts also through 150Kohm resistors (e.g. KV21)

30、. As long (The negative side of the capacitor is at -15 volts.). as the keying voltage is at or near 0 volts, the transis When a key is depressed, the capacitor is discharged tor remains off. When a key is depressed, the keying to -15 volts. The time the capacitor takes to recharge voltage drops to

31、-15 volts, which turns on the tran to 0 volts sets the release time of each note and can sistor in the array and permits the signal to pass to be varied by the release slider (R31) on the String the collector of the array and out to the mixing cir Control Board. The key voltages produced for each cu

32、itry (e.g. from pin 12 of Z31 to pin 14). key (indicated by letters KV) are supplied to two gate circuits; one for 8, one for 4. 3.2 Lower Voicing Board GENERAL: The Lower Voicing Board contains the OUTPUT Bass Low Note Priority circuitry, 4 and 8 Mixing circuitry, Gate Sensing circuitry, Suppressio

33、n Trigger circuitry, 8 and 16 Bass circuitry, Keying circuits for -15 470 keys 1 through 20, Gate circuits for tones C2 through G3, and Waveshaping for tones C2 through G3. ohm 150K 3.2.1 WAVESHAPING, KEYING AND GATE KEY CI RCUITS CONTACT (Refer to Upper Voicing Schematic, sheet 2 of 2.) , , , , , -

34、 TDA470 TRANSISTOR ARRAY 100K , WmJi SAWTOOTH WAVE (TONE) _IL SUPPRESSION TRIGGER AND STRING RELEASE CONTROL 3.3K Keying and Gating circuit BUS ROD -15V 3.1.4 GATE CI RCUITS There are a total of 10 gate transistor arrays (TDA470) in the OMNI which gate signals from the tone generator sections to the

35、 output section. Each Gate has ten transistors (on a common substrate) with common collectors and bases. The emitters serve (Refer to Lower Voicing Schematic, sheet 2 of 3.) 3.2.2 BASS LOW NOTE PRIORITY CIRCUIT (Refer to Lower Voicing Schematic, sheet 1 of 3.) The Waveshaping, Gating and Keying circ

36、uits on this board are a continuation of the circuits on the Upper Voicing Board. See sections 3 1.2, 3.1.3 and 3.1.4 for detailed descriptions. The 8 and 16 Bass section of the OMN I is single note, low note priority. The Bass section covers the lowest octave and a half of the keyboard (Keys 1 thro

37、ugh 20). The release time of the Bass section is fixed, the release control on the front panel has no control over the Bass section. Unlike the 4 and 8 polyphonic tones, the Bass Priority Circuit receives and generates only square waves. The function of the Bass Low Note Priority circuit is to route

38、 the square wave of the lowest note depressed (only) in the Bass section to the 8 and 16 Bass Wave shaping circuits (through CR41-60) for processing. 6 I The Bass Waveshaping circuits are monophonic; they may only accept one waveform at a time. Square wave tones C2-G3 are routed from the Upper Voici

39、ng Board frequency dividers to one input of a three input nor gate for each key (Z33-Z39). The outputs of these nor gates are inverted square waves only when the other two inputs are a logic 0 (e.g. Z33B pin 6 is a square wave only if pin 4 and pin 3 are at logic 0.). NOTE: All logic gates in the Ba

40、ss Low Note Priority section are COSMOS (Complimentary Symmetry Metal Oxide Semiconductor) devices. For this particular application, they are operated between ground and -15 volts. Therefore, a logic 1 is any voltage between ground and -7.5 volts, logic 0 is any voltage between -7.5 volts and -15 vo

41、lts. LJLJ (Z33-Z47) to transmit serially a logic 1 state to all keys higher than the one depressed. ENABLE ENABLE )-e (A) (C) 0-, KEYING VOLTAGE (B) 0-1 Enable (A) is a logic 0 only when Enable (C) and the Keying voltage is less than -7.5V (logic 0). The release time (decay time after keys are relea

42、sed) is fixed at about 2.5 seconds, however, an additional charge path is provided through 01-20 for those keys not depressed to shorten the release time. When no keys are depressed, 01-20 are off. The base voltage of 01-20 is always held a full diode drop above the keying (bus rod) voltage in the r

43、eference generator. -I ! (C) I-i-0 6 , (A) -. fER5ifILr 7SI9;01 c f/yOurl,r Til 1/5VtJ,A!L Y /SVSN!,C :SEAlSil -.-=-!_ f:ff!:r . .t, JI7 1 -:3J .to J7 L OWER VOICING BO. 7211901 ,. ._, =-C; . c:; fi(;:. :!,. -=-_-=C,:, . n -,5rk,v,rTRC f2 ,JW=IMIIIIII I . .Po .(f /IUE,( (JAlTRtll. 6ATE C/urT!?/6Vf =

44、rr1 =- Gt r 5)NThEj7CRW oVrpur 1 -D n m .1l1ill _ ,. QjL . j- -,-. -. v-. -,f,., . uvn - K ZERIYVTROL BO _ . SYNT;FY, P/4-1 I 5PEP(,O,v_:.J.:_ 72fH2;-,;ci,ji;C6iirn;:-:7-=-6=-=-=-r.c-_ -O;i;:C-_-F-r- I R 16 en en m 0 -.-=:.: II J4 :t,6:,_ H 19 (t15V) tf : J3 ;1 11 I:; .-JLJ!r_ t: _ / / -I ) I, J2 lX

45、- Ii ;i 6r /j PC bel KEYBOARD I , / / / , I / , ,/ H316 / /;/ /-/ /-;:.-/ -=- . U1 DESCRIPTION LINE CORD CONNECTIONS POWER CORD CONNECTIONS FINAL ASSY 240V SEMKO FINAL ASSY 20V CSA, LA BRN TO POWER SWITCH, PIN 5 BLK TO POWER SUPPLY, E- BLU TO POWER SWITCH, PIN 6 WHTTO POWER SUPPL Y, E-2 GRN/YEL TO G

46、ND SCREW GRN TO GND SCREW PIN 2 TO POWE R SUP E-3 BLK TO POWER SUPPLY, E- PIN TO POWER SUP E-4 RED TO POWER SUPPLY, E-2 NONE WHTTOPOWER SUPPLY, E FINAL ASSY 240V STANDARD BRN TO POWER SUPPLY, E- BLU TO POWER SUPPLY, E-4 GRN/YEL TO GND SCREW BLK TO POWER SUPPLY, E- RED TO POWER SUPPLY, E-2 WHTTOPOWER

47、 SUPPLY,E Cl MASTER OSCATOR I (UPPER VOICING BD) u rOPO,TAVC DIVJLJER RYO,t.I,u(j.B/).) (J l :Ero:;- r J TI)A-E561t7 ,c;/%;:Y l.rtf !,WE5 e;,hJTOC7 CONV,-TEs; NOlE,: OI_D 1Il:. ) ARt. flue , , y ooT T/A/AL c(JI,tlr :5YIIOfE5IiFCR ,()r?)T OuTPPTM/) 1 ( (,:!NT: liP.) -,- f:5fillTl-,(1?NrmLSb)I y v H vcr r,vrPEfI?EP po) I I - GAr,; Pf?(J(5SIN(j L.It;YNT.SI.!. SO) 1 :J ) -. TKI. OOT t 4C:5R GAT/N6 /_rNTkc5IZERBI I LFO .sPEED (VT,(tlL (dNT# lcJ-TR(!t BIJ) t _ /i,4f5 VOLtt,H :S(NTJIdV7Prl Sb)r f RA5.5 .Ali? (j NTH (TROlHlJ i PU OJfIVA (LOWER MJ.:W69fJ) -+-