Fender Vibrasonic AMP, Custom Vibrasonic AMP Service Manual

“CUSTOM”

VIBRASONIC AMP

p/n 021-5200-000 (120V)

SERVICE MANUAL

CONTENTS:

Notices

Specifications

Theory of operation

Parts lists:

PCB assembly

Chassis assembly

Cabinet assembly

Footswitch assembly

Miscellaneous

Schematics/diagrams

Fender Musical Instruments Corp.

7975 North Hayden Road Scottsdale, AZ 85258

“CUSTOM” VIBRASONIC

(This is the model name for warranty claims)

SERVICE MANUAL

NOVEMBER 1995

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 service. 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 maintenance and repair.

Parts marked with an asterisk (
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:

CAPACITOR CODES HARDWARE CODES

CAP AE = Aluminum Electrolytic BLX = Black Oxide
CAP CA = Ceramic Axial CR = Chrome Plated
CAP CD = Ceramic Disk HWH = Hex Washer Head
CAP MPF = Metalized Polyester Film M = Machine Screw
CAP MY = Mylar NI = Nickel Plated
CAP PFF = Polyester Film/Foil OHP = Oval Head Phillips

RESISTOR CODES

RES CC = Carbon Comp SMA = Sheet Metal "A" Point
RES CF = Carbon Film SMB = Sheet Metal "B" Point
RES FP = Flame Proof SS = Stainless Steel
RES MF = Metal Film TF = Thread Forming
RES WW = Wire Wound ZI = Zinc Plated

*

) indicate the required use of that specific part. This is necessary for RELIABILITY

PB = Particle Board
PHP = Pan Head Phillips
PHPS = Pan Head Phillips Sems

“CUSTOM” VIBRASONIC

SPECIFICATIONS

Product Release No.: PR 186 (This is not a model number)

Part Number: 120V Version : 021-5200-000

Input impedance: Input 1, both channels 1mΩ

Input 2, both channels 132kΩ

Power Output: 85 Watts RMS minimum @ 5% THD

Rated load impedance: 4Ω

Speaker Complement: (1) 15” “Special Design” (p/n 049135)

Dimensions: Height:22" (55.9 cm)

Width: 26 5/32" (66.4 cm)
Depth: 10 3/8" (26.4 cm)

Weight: 71 lbs. (32.3 kg)

Product specifications are subject to change without notice

“CUSTOM” VIBRASONIC

THEORY OF OPERATION

STEEL CHANNEL

J1 is the high sensitivity input and J2 is the low sensitivity input. The input is fed to V1A, which proveds a gain of
about 42. The output from V1A drives the Treble (R7), Mid(R9), and Bass(R7) tone controls, then feeds the Volume
control (R10). When engaged, the SWEET switch connects C5 to the wiper of the VOLUME control. This provides a
boost in the high frequencies. The “Sweet” feature is most noticeable at lower volume settings. The signal then
feeds to V1B, which provides a gain of about 66.

GUITAR CHANNEL

J3 is the high sensitivity input and J4 is the low sensitivity input. V2A contains the FAT switch which boosts the gain
mostly at lower and mid frequencies. V2A drives the tone controls, and the Volume control (R21) feeds V2B.
V1B and V2B share the same cathode resistor (R23) and bypass capacitor (C11). The output of the Steel channel
(V1B pin 6) sums with the output of the GUITAR channel at V2B pin 6. From that point the signal follows two paths.
One to the reverb drive stage (V3). The other through R32 to summing amp V4B.

REVERB

V3 (12AT7) provides a gain of about 33 to drive the reverb transformer. V4A is the Reverb recovery or sense stage.
The Reverb control (R29) determines the amount of reverb signal that is summed with the dry signal at V4B. Via the
footswitch, the Reverb can be disabled by grounding the signal at the node between R30 and R74.

VIBRATO

V5A is a low frequency oscillator. The Speed control (R56) varies the oscillation frequency. V5B is the Neon Lamp
driver. The lamp flashes faster or slower based on the position of the Speed control (R56). The brightness of the
neon bulb is sensed by the LDR (Light Dependent Resistor). The LDR connects to the Intensity control (R64) which
varies the amount of low frequency modulation applied to the input of the Phase Inverter(V6).

POWER AMPLIFIER

The output from V4B feeds the Phase Inverter(V6), which is a classic style split-load type, used without feedback.
The output tubes (5881/6L6WGC) are arranged in a push-pull configuration that will produce 85 watts minimum into a
four(4) Ω load at 5% THD.

PARTS LIST

PRINTED CIRCUIT BOARD ASSEMBLY

QTY PART # DESCRIPTION REFERENCE DESIGNATION

1 049266 PCB ASSY CUSTOM VIBRASONIC ALLV (STUFFED)
3 037805 CABLE RIBBON 6CKT 2-1/4”
1 031069 CAP AE RDL 10uF 100v 20% C37
5 028465 CAP AE RDL 22uF 25V 20% C6 C11 C14 C27 C28
1 036954 CAP AE RDL 22uF 63V 20% C36
3 024819 CAP AE AX 22uF 500v 20% C32 C33 C34
1 031040 CAP AE RDL 100uF 100V 20% C35
2 013638 CAP AE AX 200uF 285V 20% C30 C31
2 025979 CAPCD 50pF 1KV 10% C5 C10
1 031780 CAP SLVR MICA 150PF 300V C7
1 007029 CAPCD 220pF 1KV 10% C38
1 020917 CAPCD 250pF 1KV 10% C2
1 020842 CAPCD 500pF 1KV 10% C13
1 047065 CAP PFF RDL .0015uF 100V C16
1 037666 CAP PFF .001 uF 400v 10% C20
2 024823 CAP MPF RDL .01uF 400V 10% C25 C26

“CUSTOM” VIBRASONIC

PRINTED CIRCUIT BOARD ASSEMBLY (CONT)

QTY PART # DESCRIPTION REFERENCE DESIGNATION

2 024833 CAP MPF RDL .022UF 400V 10% C12 C24
2 024835 CAP MPF RDL .022UF 630V 10% C9 C40
1 024845 CAP MPF RDL .047UF 400V 10% C4
1 024846 CAP MPF RDL .047UF 630V C8
1 024853 CAP MPF RDL .1UF 250V 10% C21
2 024854 CAP MPF RDL .1UF 400V 10% C3 C19
2 024855 CAP MPF RDL .1UF 630V 10% C22 C23
2 037596 CONTROL SNAPIN 1M 30A R10 R21 (VOLUME)
1 037601 CONTROL SNAPIN 3M 30C R56 (SPEED)
1 028421
1 017502 CONTROL 10K B SCREW ADJ R71 (BIAS ADJUST)
2 037598 CONTROL SNAPIN 10K 10A R9 R20 (MID)
1 037602 CONTROL SNAPIN 50K 30C R64 (INTENSITY)
1 037600 CONTROL SNAPIN 100K B R29 (REVERB)
2 037599 CONTROL SNAPIN 250K 10A R8 R19 (BASS)
2 037597 CONTROL SNAPIN 250K 30A R7 R18 (TREBLE)
1 064089 DIODE 1N4003 200PRV 1AMP CR5

4 026730 DIODE 1N4006/1N5062 800PRV 1A CR1 CR2 CR3 CR4
15 026000 FASTON TAB .187 CP17 THRU CP31
16 025802 FASTON TAB .250 CP1 THRU CP16

3 027413 HEADER .1” CTR 6 CIRCUIT P1 P2 P3

4 037117 JACK PHONE PCB MONO CLOSED CKT J1 J2 J3 J4 (INPUTS)

1 025933 JACK PHONO DUAL PC MTG J8 (REVERB PAN CONN.)

1 037836 OPTOISOLATOR ASSY 65 TWIN OP1

1 037628 PCB 65 TWIN REVERB (RAW PCB)

1 024937

2 024964

4 024969 RES CF 1/4W 1.5K 5% R5 R16 R26 R27 R46-49

1 024972 RES CF 1/4W 2.7K 5% R60

1 024981 RES CF 1/4W 10K 5% R75

5 024995 RES CF 1/4W 68K 5% R1 R2 R12 R13 R77

1 024996 RES CF 1/4W 82K 5% R74

1 029613 RES CF 1/4W 91k 5% R55

2 024997 RES CF 1/4W 100k 5% R6 R17

4 025059 RES CF 1/4W 220K 5% R31 R35 R44 R45

1 025060 RES CF 1/4W 270k 5% R76

1 025063 RES CF 1/4W 390k 5% R30

7 025069 RES CF 1/4W 1 1M 5% R3 R14 R24 R37 R38 R57 R58

1 025074 RES CF 1/4W 1.8M 5% R59

1 025077 RES CF 1/4W 3.3M 5% R32

1 025084 RES CF 1/4W 10M 5% R63

1 028861 RES CF 1/2W 27K 5% R70

1 037665 RES CF ½W 27K 5% R72

8 025116 RES CF 1/2W 100K 5% R4 R11 R15 R22 R28 R33 R61 R62

3 025117 RES CF 1/2W 220K 5% R54 R65 R66

3 037664 RES FP 1W 1K 5% R67

1 027347 RES CF 1W 2.2K 5% R25

1 036469 RES FP 1W 4.7K 5% R68

1 027350 RES CF 1W 22K 5% R36

1 027352 RES CF 1W 91K 5% R43

1 027353 RES CF 1W 100K 5% R42

2 037835 SWITCH SLIDE SPST S4 S5

1 028503

CONTROL 100Ω D FOJ SCREW ADJ

RES CF ¼W 10Ω 5%
RES CF 1/4W 820Ω 5%

THERMISTOR 10Ω 5A C60-11

R69 (HUM BALANCE)

R73
R23 R41

THI

QTY PART # DESCRIPTION REFERENCE DESIGNATION

1 049516 CHS ASSY 120V CUST. VIBRASONIC (COMPLETE CHASSIS)

1 037582 CHS 65 TWIN REVERB (RAW)

7 018022 BUSHING SNAP 5/16 X 17/32 BLK

1 026038 BUSHING STRAIN RELIEF (100V/120V AC CORD)

CHASSIS ASSEMBLY

“CUSTOM” VIBRASONIC

CHASSIS ASSEMBLY (CONT)

QTY PART # DESCRIPTION REFERENCE DESIGNATION

1 010401 BUSHING STRAIN RELIEF (220V/240V AC CORD)

1 026541 CABLE ASSY PWR W/.50 TAB 120V (POWER CABLE 120V ONLY)

1 048463 CABLE ASSY PWR .250 TAB 100V (POWER CABLE 100V ONLY)

1 033331 CABLE ASSY PWR 220/240V (POWER CABLE 230V ONLY)

1 038602 CABLE ASSY PWR AUST .250 TAB (PWR CABLE AUSTRALIA 240V)

1 040993 CABLE ASSY PWR 5A U.K. .250 TAB (P CABLE UNITED KINGDOM 240V)

1 036486 CHOKE FILTER L1

1 022491 CLAMP CABLE SCRW MNT

1 028421

1 017502 CONTROL 10K 20% SCREW ADJ. R71 (BIAS ADJUST)

1 037854 COVER CAPACITOR

1 013737 FUSE TD 1-1/4X1/4 250V 4A F1 (100V/120V)

1 013115 FUSE TD 20MMX5MM 250V 2A F1 (220V/240V)

1 036702 FUSEHOLDER 3AG FINGER GRIP XF1 (100V/120V)

1 036703 FUSEHOLDER 5MM FINGER GRIP XF1 (220V/240V)

1 021550 JACK PHONE TIP SHUNT 12A J5 (SPEAKER OUT)

1 021956 JACK PHONE OPEN CIRCUIT 11 J6 (EXT. SPEAKER OUT)

1 013043 JACK PHONE STEREO 12B J7 (FOOTSWITCH)
11 024604 KNOB BLACK W/ WHITE STAMP 14000

1 027887 LUG SOLDER 3/8 (HUM BAL. WIPER GND)

5 016352 NUT HEX 3/8-32X3/32 TK NI (HUM BIAS, OUTPUT, FTSW)

8 022004 NUT KEPS #8-32 (XFMR MOUNTING)

1 049115 PANEL FRONT VIBRASONIC

1 049116 PANEL REAR VIBRASONIC

1 032219 PILOT LIGHT COLLAR

1 021642 PILOT LIGHT #47

1 021741 PILOT LIGHT HOLDER

1 031625 PILOT LIGHT NUT

1 036595 PILOT LIGHT LENS JEWEL RED

4 024969 RES CF 1/4W 1.5K 5% R46-49 (@PWR TUBE SCOKETS)

4 021402

4 027979 SCREW M 4-40X1/4 PHP NI (SLIDE SWITCHES)
14 028937 SCREW TF 6-32X5/8 PHP ZI (MAIN PCB) (CAP PCB)

1 9904101560 SCREW 6X3/8 HI-LO PHP BLX (RCA JACK)

4 016473 SCREW MA 8-32X1/2 PHP ZI (OUTPUT XFMR)

1 032806 SCREW MA TF 6-32X1/4 BLX (REAR PANEL)
30 029913 SCREW TF 6-32X3/16 PHP ZI (TUBE SOCKETS, CHOKE, REVERB, XFMR)
10 025936 STAND OFF PCB PUSH ON

5 037783 STAND OFF PCB PUSH ON 1/4L

1 036570 SWITCH TOGGLE DPST S1 (POWER OFF/ON

1 037039 SWITCH TOGGLE SPST S3 (STANDBY)

1 037612 XFMR OUTPUT 65 TWIN T2

1 049181 TRANSFORMER POWER (EXPORT) T1 (100V/110/120/220/230/240V

1 037610 TRANSFORMER POWER 120V T1 (DOMESTIC)

1 037099 TRANSFORMER REVERB T3

4 020424 TUBE RING UNIVERSAL (277H-2) (POWER TUBES)

4 023580 TUBE SOCKET 8 PIN

6 041267 TUBE SOCKET 9 PIN PORCEL W/SHIELD

2 023531 TUBE VACUUM 12AT7 V3 V6

4 039214 TUBE VACUUM 5881/6L6WGC V7 V8 V9 V10

4 013341 TUBE VACU 7025/12AX7WA RUSSIAN V1 V2 V4 V5

3 022293 WASHER FLAT .473 X .750 (SWITCHES POWER, STANDBY)

3 031153 WASHER FLAT 3/8X.614 NI (JACKS SPEAKER, FTSW)

4 9904300100 WASHER LCK INTL 3/8X.618 (JACKS SPEAKER, FTSW, HUM BALANCE)

CONTROL 100Ω SCREW ADJ.

RES CC 1W 470Ω 10%

R69 (HUM BALANCE)

R50-53 (@ PWR TUBE SOCKETS)

QTY PART # DESCRIPTION REFERENCE DESIGNATION

1 049109 CABINET ASSY CUSTOM VIBRASONIC

1 049109030 BACK ASSY LOWER VIBRASONIC (BACKBOARD)

1 049109020 BACK ASSY UPPER VIBRASONIC (BACKBOARD)

CABINET ASSEMBLY

“CUSTOM” VIBRASONIC

CABINET ASSEMBLY (CONT)

QTY PART # DESCRIPTION REFERENCE DESIGNATION

1 038566 CABLE ASSY SPKR RT ANG 13-1/2” (SPEAKER CABLE)

1 025722 CABLE REVERB 1100MM

4 026566 CORNER 2 HOLE W/TAB NI

4 024653 GLIDE CAB 1.24X.335 NI (STEEL ONLY)

4 019275 GLIDE-INSERT CUSHION 1.27 DIA (RUBBER ONLY)

1 049109010 GRILLE BAFFLE ASSY VIBRASONIC (COMPLETE GRILLE)

REF 037788 GRILLE CLOTH BLACK/SILVER

1 049094 HANDLE MOLDED BACK

2 024828 LEG AMP TILT 16”

1 047600 NAMEPLATE LOGO BLACK

2 021998 NUT LOCK 10-32 W/ NYLON INSERT (@TILT BACK LEGS)

4 064162 NUT-T 8-32X1/2 STR 3 PRNG BLX (HANDLE MOUNTING)

8 021972 NUT T 10-32X3/4 STR 3 PRNG BLX (SPEAKER MOUNTING)

1 031849 REVERB BAG

1 064063 REVERB UNIT 4 SPRING 4AB3C1B (PAN)

4 037210 SCREW SMA 2X 3/8 OHPNI (NAMEPLATE MOUNT)

4 037247 SCREW M 8-32X1 OHP NI (HANDLE MOUNTING)

4 022236 SCREW M 8-32X3-1/4 OHP NI (CHASSIS MOUNTING)

8 037543 SCREW SMAB 8X3/4 OHP NI (CORNER MOUNTING)

4 026625 SCREW WOOD 8X1” FLAT HEAD (GLIDE MOUNTING)

2 031344 SCREW SMA #6X1 OHP NI (@ LEG STOP)

8 026577 SCREW M 10-32X1 PHP BLX (SPEAKER MOUNT)

2 022277 SCREW M 10-32X1-1/2 OHP NI (TILT BACK LEGS)

8 037952 SCREW SMA #6X1 OHP NI (BACKBOARD MOUNT)

7 029828 SCREW PB #8X33/4 PHP ZI (REVERB/REAR CHASSIS MOUNT)

1 049135

2 024752 STRAP CHASSIS 4-1/2” NI (CHASSIS MOUNTING)

8 037215 WASHER C’SINK #6 NI (BACKBOARD MOUNT)

2 022285 WASHER SP LOCK 1/4X9/16 NI (TILT BACK LEGS)

6 022319 WASHER FLAT 1/4X9/16 NI (TILT BACK LEGS)

2 024646 WASHER LEG STOP TN (TILT BACK LEGS)
11 029527 WASHER FINISH #8X5/8 BLX (GRILLE MOUNTING)

2 022327 WASHER FLAT #8X7/16 NI (REVERB MOUNTING)

SPEAKER 15” 4Ω CAST FRAME

FOOTSWITCH ASSEMBLY

QTY PART # DESCRIPTION REFERENCE DESIGNATION

1 037211 FOOTSWITCH VIRBRO//’65 TWIN (COMPLETE FOOTSWITCH)

1 021691 BUSHING SR.500X.100X7/16 BLK (STRAIN RELIEF)

1 022665 COVER CUP DUAL FTSW ASSY (BLACK, SNAP ON)

1 024638 CUP FOOTSWITCH DUAL (HOUSING 2 BUTTON)

1 016063 DECAL FOOTSWITCH VIBRATO +R (VIBRO/REVERB)

1 013172 PLUG PHONE 3 CONDUCTOR 238 RA

2 024042 SWITCH SPST PUSHBUTTON S6 S7 (FOOTSWITCHES)

2 022293 WASHER FLAT .473X.750 NI

REF 023861 WIRE BLACK 2 CONDUCTOR (SHIELD OVER 1 COND)
REF 023945 WIRE BRAIDED SHIELD (INTERNAL GRND JUMPER)

MISCELLANEOUS

QTY PART # DESCRIPTION REFERENCE DESIGNATION

1 049515 MANUAL OWNERS CUSTOM VIBRASONIC

1 049264 SCHEM REDU W/SVC DIA VIBRASONIC