Fender_twin_94 电路图 维修原理图.pdf

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1、94 TWIN AMP p/n 02-4809-000(120V) SERVICE MANUAL CONTENTS: Notices Specifications Parts lists: PCB assembly Chassis assembly Cabinet assembly End item Schematics/diagrams Fender Musical Instruments Corp. 7975 North Hayden Road Scottsdale, AZ 85258 收音机爱好者资料库 Ra d i o Fa n s .CN 94 TWIN AMP (This is t

2、he model name for warranty claims) SERVICE MANUAL JUNE 1995 REV A TYPE PR266 IMPORTANT NOTICE: The information contained herein is CONFIDENTIAL and PROPRIETARY to Fender Musical Instruments Corp. It is disclosed solely for use by qualified technicians for purposes of equipment maintenance and servic

3、e. It is not to be disclosed to others without the expressed permission of Fender Musical Instruments Co. All specifications subject to change without notice. For warranty repair service, only Fender specified part numbers are to be used. It is recommended they also be used for post-warranty mainten

4、ance and repair. Parts marked with an asterisk (*) indicate the required use of that specific part. This is necessary for RELIABILITY and SAFETY requirements. DO NOT USE A SUBSTITUTE! A coded naming convention is used in the description of certain parts. The codes and what they mean are as follows:

5、CAPACITOR CODES HARDWARE CODES CAP AE=Aluminum ElectrolyticBLX=Black Oxide CAP CA=Ceramic AxialCR=Chrome Plated CAP CD=Ceramic DiskHWH=Hex Washer Head CAP MPF=Metalized Polyester FilmM=Machine Screw CAP MY=MylarNI=Nickel Plated CAP PFF=Polyester Film/FoilOHP=Oval Head Phillips PB=Particle Board RESI

6、STOR CODESPHP=Pan Head Phillips PHPS=Pan Head Phillips Sems RES CC=Carbon CompSMA=Sheet Metal A Point RES CF=Carbon FilmSMB=Sheet Metal B Point RES FP=Flame ProofSS=Stainless Steel RES MF=Metal FilmTF=Thread Forming RES WW=Wire WoundZI=Zinc Plated 收音机爱好者资料库 Ra d i o Fa n s .CN 94 TWIN AMP SPECIFICAT

7、IONS Product Release No.:PR 266 (This is not a model number) Part Number:120V Version :21-4809 230V Version : 21-4889 Power Requirements:120V Version: 120 volts AC, 60 HZ, 360 watts. 230V Version: 230 volts AC, 50 HZ, 360 watts. Input Impedance:Input 1: 1M Input 2: 136k Effects Loop:Pre Reverb. Nomi

8、nal Level: +2, -5.5, -13 dbv Output Impedance: 4.2k maximum Input Impedance: 130k minimum Effects Mix Control:Continuously variable between the signal at the EFFECTS SEND and EFFECTS RETURN jacks. Reverb:Post effects loop. Preamp Out: Post reverb, +1.3 dbv nominal level. Recommended load: 22 k minim

9、um. Power amp in:+1.3 dbv sensitivity, 1130k input impedance. Balanced Line Output:Derived from the output transformer, fully balanced. +3 dbv nominal level into 600 or greater. Pin 1 floating, pin 2 (+), pin 3 (-) Amplifier Load Impedance:Switch selectable for 4, 8, or 16 . Power Output:OUTPUT HIGH

10、 setting: 100 watts RMS, 5% THD. OUTPUT LOW setting: 25 watts RMS, 5% THD. Speaker Complement:Two Fender P.N 026488 Special Design 12” 8 ohm speakers wired in series. Dimensions:Height:20 3/4”(52.7 cm) Width: 26 3/8”(67 cm) Depth: 11 1/2”(29.2 cm) Weight: 77 lbs.(35 kg) Product specifications are su

11、bject to change without notice 收音机爱好者资料库 Ra d i o Fa n s .CN 94 TWIN AMP THEORY OF OPERATION INPUTS J1 and j2 are high and low sensitivity inputs that feed the first preamp stage (V1A). V1A provides a gain of about 38 for channel 1, and about 49 for channel 2. The gain difference is due to different

12、 loading of the plate of V1A. The signal then couples to relay K1B, which routes it to the channel one or channel two circuitry. CHANNEL ONE The 94 Twin Amp is a direct descendent of classic tube amps like the Twin Reverb and the 410 Bassman. Channel one is the traditional Fender design which offers

13、 the vintage sound as well as contemporary sounds with the use of switch-selectable Gain and Master Volume controls. Its like two channels in one. The first stage of Channel One contains the Treble (R17), Bass (R18) and Mid (R19) tone controls. The signal from the Treble control feeds through Relay

14、K2B, which routes the signal to either the Clean or Vintage Overdrive section of channel one. CLEAN The signal from pin 11 of Relay K2B feeds through the Clean Volume control (R11) to V1B. R12 and C4 provide the Bright boost feature via a pull switch on the Clean Volume control. V1B provides a gain

15、of about 45. The Clean channel circuitry terminates at pin 6 of Relay K2A. K2A selects between the output of the Clean or Vintage Drive circuit. VINTAGE DRIVE The signal from Pin 9 of Relay K2B feeds through the Gain control (R8) to the first stage (V2A) of the Vintage Drive circuitry. V2A provides

16、a gain of about 20, then drives the second gain stage (V2B). V2B provides a gain of about 48; then couples the signal to the vintage drive Volume control (R23), which also contains the select switch for the Clean/Drive feature. When in the Channel 2 mode, Relay K1A connects the wiper of the Gain con

17、trol (R8) to ground, muting the input to the Vintage Drive stage. The Vintage Drive circuit terminates at pin 8 of Relay K2A. CHANNEL TWO Channel Two is like owning a second, modern hot-rodded amp with more soaring gain than previously found in a Fender tube amp. The signal from pin 9 of Relay K1B f

18、eeds through the Channel Two Gain control (R25) to the first (V3A) and then second (V3B) stage of the overdrive circuitry. From V3B, the signal is fed to through the Treble (R35), Bass (R36), and Mid (R37) tone controls. Finally the signal travels through the channel two Volume control (R39), which

19、also contains the Channel Select switch. Channel two terminates at pin 9 of Relay K4B. K4B selects between channels one and two. EFFECTS LOOP The selected (Ch-1 or Ch-2) signal from Relay K4B is fed to a Split-Load Phase Inverter (V4A). The output from Pin 1 of V4A follows two paths to Relay K3A. On

20、e path travels through one half of the Mix control. The second path connects directly to K3A. The signal from Pin 3 of V4A drives the Effects Send Jack (J3), and is normalled to the Effects Return jack (J4). The Effects Level switch provides three signal levels for matching a wide variety of externa

21、l signal processing devices. The switch also maintains unity gain between the Send and Return jacks. The signal from the Effects Return jack feeds V4B, then travels through the other half of the Mix control (R44B), and to Relay K3B. The dry and wet signals sum together through R54 and R55. Relay K3

22、is controlled by the Effects Select switch in the Both position, K3 will be in the Normally Closed position. Any signal available at the Effects Return jack will pass, whether in Ch-1 or Ch-2. The Mix control will be active. With the Effects Select switch in the Ch-1 position, the Effects Return wil

23、l be active while the amp is in the Ch-1 mode. When the amp is switched to the Ch-2 mode, the control voltage from U2B will energize relay K3, K3A will toggle, bypassing one half of the Mix control (R44A), and K3B will break the connection from the Effects Return. Therefore the Effects Return will b

24、e active only for the channle that is selected by the Effects Select switch. REVERB The signals from Relays K3A connect the test probes to the test points (J11 & J12) labeled “Bias”. Adjust the Output Bias Adjust control (R94) to read .08 VDC (80mVDC). This will Bias V9 &V10. Now connect the test pr

25、obes across the “Balance” test points (J10 & J11). The meter is now referenced to the 80mVDC instead of ground. Adjust the Output Balance Adjust control to obtain 0VDC. This precisely matches V11 & V12 to V9 & V10. For optimum sonic performances, set Bias to 80mVDC, then set Balance. For optimum son

26、ic performance with increased tube life, set Bias to 60mVDC, then set Balance. For optimum tube life, set Bias to 40mVDC, then set Balance. Note: If a bias measurement of 40mVDC cannot be obtained, it may be time to replace the output tubes. CHANNEL/REVERB SWITCHING A 27.5VAC signal is tapped off fr

27、om the Brown secondary of the power transformer. This signal is presented to the Footswitch jack. By rectifying the positive or negative half of the waveform, a DC control voltage is created. This voltage is used to control several opamp comparator circuits. TROUBLESHOOTING TIP Most channel switchin

28、g problems will probably be related to intermittent or sticky relays. However troubleshooting the switching circuitry is easy. All test point voltages are on the schematic. First verify the reference voltage at the comparator. The reference voltage is applied to the non-inverting input of the opamp.

29、 Then measure the output of the comparator. If it doesnt toggle properly, check the control voltage. If the control voltage is not correct, hang a scope probe on the footswitch jack. Look at the AC waveform, activate the channel select switches, and look for the rectified waveform. The Reverb is swi

30、tched by rectifying the negative side of the waveform. The Gain Select and Channel Select are switched by rectifying the positive side of the waveform at two different voltage levels. Diode CR16 and Zener CR18 set the two voltage levels. POWER LEVEL SWITCHING Via the output switch (S9) the output po

31、wer of the amplifier can be switched between 25 and 100 watts. S9A selects between the center tap and full winding of the high voltage secondary of the power transformer. This causes the B+ and Z supplies to 94 TWIN AMP THEORY OF OPERATION(CONT) switch from +454Vdc to +230Vdc. This voltage change on

32、ly affects the four output tubes. The high voltage supplies for the preamp tubes are tapped off prior to the output switch (S9). When switching the high voltages at the power tubes, the negative Bias voltage must also be switched. The Bias supply is derived through a voltage doubler from the Brown s

33、econdary of the power transformer. S9B determines the path of the Bias current. The low power path is through R97 (100K), and the high power path is through R98 (18K) and R97 (100K) in parallel. R96 (82K) sets up the voltage divider that feeds the Bias and Balance controls (-52Vdc High, -21 Vdc Low)

34、. Note: It is recommended that the amplifier be in the Stand-by mode before switching the High/Low Output switch. LOW POWER OPTION The 94 Twin Amp can be run with only two output tubes instead of four. This is done by removing the inner two 5881/6l6wgc tubes. The Impedance Selector switch must be se

35、t to one-half the total speaker load. The rule is -half the tubes-half the impedance. Therefore when using the internal two speakers (16 load), the Impedance Selector switch must be set to 8 . This will produce 60 watts RMS in the Output High setting, and 15 watts RMS in the Output Low setting. PART

36、S LIST NOTE: SHADED ITEMS ARE FOR REFERENCE ONLY PRINTED CIRCUIT BOARD ASSEMBLY QTY PART # DESCRIPTION REFERENCE DESIGNATION 1048973CABLE RIBBON 9 CKT 15 INP3A 1048972CABLE RIBBON 9 CKT 9 INP2A 1038691CAP AE AX 4.7 UF 50VC35 7009512CAP AE AX 22 UF 25V 20%C1,5,11,24,28,53,61 4024819CAP AE AX 22UF 500

37、VC22,42,43,44 4036954CAP AE RDL 22UF 63V 20%C36,37,59,62 4024820CAP AE AX 47UF 350VC40,41,51,52 1028471CAP AE RDL 47UF 50V 20%C60 2031040CAP AE RDL 100UF 100V 20%C45,50 2013638CAP AE AX 220UF 285VC38,39 2028482CAP AE RDL 220UF 50V 20%C46, 49 2039362CAP AE RDL 1000UF 35V LOPROFILC47,48 1025982CAP CD

38、68PF 1000V 10%C4 2020917CAPCD 250 PF 1000V 10%C6, 17 1025777CAP CD 470PF 1000V 10%C25 2011435CAP CD 680PF 1000V 10%C13,27 1017620CAP CD 1500PF 1000V 10%C31 1039265CAP CA 2200PF 100VC30 2026202CAP PFF .0022UF 600VC10,14 3025962CAP PFF .0047UF 400VC12,29,65 2027275CAP MPF .068 UF 100VC57,58 7024833CAP

39、 MPF RDL .022UF 400V 10%C3,8,9,16,18,26,63 2024835CAP MPF RDL .022UF 630V 10%C32,33 2024853CAP MPF RDL .1UF 250V 10%C23,34 5024854CAP MPF RDL .1UF 400V 10%C2,7,15,19,21 2027281CAP MPF .22UF 63VC55,56 1027286CAP MPF .47UF 63VC54 1024876CAP MPF RDL .68UF 250V 10%C20 1049028CONTROL POT 1M 2B W/DPDTR39

40、(CHANNEL 2 VOLUME) 1047781CONTROL SNAPIN 1K 15CR82 (PRESENCE) 2041510CONTROL SNAPIN 25K BR19, 37 (CHANNELS 1&2 MID) 1037600CONTROL SNAPIN 100K BR62 (REVERB) 4037597CONTROL SNAPIN 250K 30A R17,18,35,36 (CHANNELS 1&2 TREBLE,BASS) 1047780CONTROL SNAPIN 250 K 30AR23 (CHANNEL 1 DRIVE VOLUME) 94 TWIN AMP

41、PRINTED CIRCUIT BOARD ASSEMBLY (CONT) QTY PART # DESCRIPTION REFERENCE DESIGNATION 1041511CONTROL SNAPIN 250K B DUALR44 (MIX) 1041512CONTROL SNAPIN 1M 30AR11 (CHANNEL 1 CLEAN VOLUME) 2037596CONTROL SNAPIN 1 MEG J TAPERR8,25 (CHANNELS 1,2 GAIN) 2026133CONTROL TRIM 25K LINR92,94 (BIAS/BALANCE ADJUST)

42、11026730DIODE 1N4006 800VCR2,3,5-11, 14, 15 14006260DIODE 1N4448 SIGNALCR16,17,19,20,22-30,32 2031729DIODE ZEN 1N5231B .5W 5.1V 5%CR18, 31 1028990RES CF W 5% 51KR50 2024995RES CF W 5% 68KR1,2 1024996RES CF W 5% 82KR96 8024997RES CF W 5% 100KR16,24,34,59,70,71,97,153 7028955RES CF W 5% 130KR51,54,55,

43、93,95,142,147 1025058RES CF W 5% 180KR49 7025059RES CF W 5% 220KR22,26,29,32,58,64,141 1028016RES CF W 5% 300KR125 4025065RES CF W 5% 470KR63,76,77,129 14025069RES CF W 5% 1M R3,6,7,40,56,118,121,123,127,128,135,138,156,157 1025077RES CF W 5% 3.3mR65 2025084RES CF W 5% 10MR12,38 2041741RES MOX FP W

44、5% 47R108,109 1025941RES CF W 5% 560R57 1026549RES CF W 5% 1.5KR134 1026493RES CF W 5% 2.7KR120 1031065RES CF W 5% 91KR146 9025116RES CF W 5% 100KR5,10,15,21,27,30,61,67,140 6025117RES CF W 5% 220KR99-102,110,111 2033095RES MOX FP 1W 5% 1R89,90 1037354RES FILM 1W 5% 4.7KR80 1041739RES MOX FP 1W 5% 6

45、.8KR104 1027349RES FILM 1W 5% 10KR42 1041738RES CF 1W 5% 15KR43 1027350RES FILM 1W 5% 22KR79 1027352RES FILM 1W 5% 91KR73 1027353RES FILM 1W 5% 100KR72 1041277RES CF 2W 5% 820R112 1041740RES MOX FP 2W 5% 4.7KR103 1041737RES CF 2W 5% 33KR53 2036924RES WW BT 5W 10% 1KR91,154 2029047RES WW BT 7W 10% 27

46、0R106,107 1041742RES WW VT 7W 10% 10KR105 3038652SWITCH SLIDE 4P3TS4-6 9026001TERMINAL EYELET W/ LUG1 1028503THERMISTOR 10 5A C60-11TH1 1041261VOLT REF LM4040DCZ-10V TO-92U1 1014689XSTR N-CH JFET J111 TO-92Q1 CHASSIS ASSEMBLY QTY PART # DESCRIPTION REFERENCE DESIGNATION 4016473SCRW M 8-32X1/2 PHP ZI

47、(OUTPUT TRANSFORMER MOUNT) 1028684SCRW SMB 6X3/8 PH PHS BLX(J6, REVERB RCA JACKS) 2026521SCRW SMB RX3/8 RH PHS BLK( J13, BALANCED LINE OUT) 15028937SCRW TF 6-32X5/8 PHPZI TAPTYT(PCB TO CHASSIS MOUNT) 15025936STANDOFF NYLON PCB SNAPIN 3/8”(PCB TO CHASSIS MOUNT) 1026472SWITCH SLIDE DPTTS10 (IMPEDANCE

48、SELECT) 2036570SWITCH TOGGLE DPST W/ NUTSS7,8 (POWER, STANDBY) 1049976SWITCH TOGGLE DPST W/ LEADSS9 (OUTPUT HIGH,LOW) 3023531TUBE 12AT7VR4,5,8 5013341TUBE 7025/12AX7A SOVIET MADEV1,2,3,6,7 8023598TUBE SHIELD(V1,2,3,4,5,6,7,8) 94 TWIN AMP CHASSIS ASSEMBLY (CONT) QTY PART # DESCRIPTION REFERENCE DESIGNATION 4023580TUBE SOCKET 8 PINXV9,10,11,12 8023606TUBE SOCKET 9 PINXV1,2,3,4,5,6,7,8 4039214TUBE VACUUM 5881/6L6WGCV9,10,11,12 29904300100WASHER LCK INTL 3/5X.681X.032(J14,16) 2026564WSHR FLAT .284X1/2ZI(R92,94 BIAS/BALANCE POTS) 3027520WSHR FLAT .380X.630 FIBER(J14,15,16) 8