BLUES JUNIOR
SERVICE MANUAL
CONTENTS:
Notices Specifications Theory of operation Parts lists:
PCB assembly Chassis assembly Cabinet assembly Miscellaneous
Schematics/Service diagram
Fender Musical Instruments Corp., 8860 E. Chaparral Road Suite 100 Scottsdale, AZ 85250
BLUES JUNIOR
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 asterick (*) 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:
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 |
PB |
= |
Particle Board |
||
PHP |
= |
Pan Head Phillips |
|||
|
|
|
PHPS |
= Pan Head Phillips Sems |
|
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 |
|
BLUES JUNIOR |
|
|
|
SPECIFICATIONS |
|
|
Type |
PR 295 |
|
|
Input impedance: |
1M ohm |
|
|
Power output: |
15 Watts R.M.S. @ 5% T.H.D |
||
Rated load impedance: |
8 Ohms |
|
|
Speaker compliment |
One 8 ohm 12" Eminence, |
||
|
replica of Jenson P-10 |
||
Dimensions: |
|
|
|
Height: |
16 |
inches |
(41 cm) |
Width: |
18 |
inches |
(46 cm) |
Depth: |
9-13/16 inches |
(25 cm) |
|
Weight: |
31 lbs. |
(14 kg) |
|
THEORY OF OPERATION
J1 is a high-sensitivity input with an input impedance of about 1MΩ. V1B is the first gain stage which also contains the "FAT" switch. The FAT feature is activated by grounding the node between bypass capacitor C3 and R9. Via the FAT switch (S1) or the optional footswitch, the junction of R52 and R54 can be grounded. With zero volts applied to the gate of Q1, the JFET will essentially ground C3, activating the FAT feature.
The output of V1B couples to the VOLUME control (R7). The VOLUME control is actually a preamp overdrive control that adjusts the level of distortion. C2 attenuates high frequencies and C1 attenuates low frequencies at high distortion settings. This takes the edge off the distortion and prevents the speaker from flapping. V1A provides a gain of about 40, and drives the tone control circuitry. After the tone controls, the signal is fed to V2B, which drives the
MASTER volume control (R41). From the MASTER volume, the signal splits to feed the power amplifier and the Reverb.
U1A makes up a typical solid-state reverb drive circuit. U1B is the reverb recovery or sense circuit, which drives the REVERB control (R51). The reverb signal is summed with the dry signal at C6, which couples to the input of the Phase Inverter (V3).
The output tubes (6BQ5/EL84) are arranged in a push-pull configuration that will produce fifteen (15 ) watts R.M.S. into eight (8) ohms @ 5% THD, 1kHz.
The output bias is derived from the -15Vdc supply. The voltage divider at R31 & R37 determines the bias voltage (-10.7 Vdc). C14 filters the ripple to 1mV or less.
BLUES JUNIOR
PARTS LIST
|
|
PRINTED CIRCUIT BOARD ASSEMBLY |
|
||||
QTY |
PART # |
DESCRIPTION |
|
|
REFERENCE DESIGNATION |
||
1 |
049306001 |
PCB ASSY BLUES JUNIOR ALL V |
|
(STUFFED) |
|
||
1 |
028104000 |
BUTTON PUSH SWITCH BLACK |
|
(@ S1) |
|
||
2 |
047093000 |
CABLE 6 CKT 3.2" |
|
|
CJ1,3 |
|
|
3 |
029533000 |
CABLE JMPR 22GA 4 CKT 3.2" |
|
CJ2,4,5 |
|
||
1 |
028577000 |
CABLE REVERB 30" |
|
|
(@ P1,2,3,4) |
||
1 |
038689001 |
CAP AE AX |
.47µF |
100V |
|
C23 |
|
3 |
009512001 |
CAP AE AX |
22µF |
25V |
20% |
C3,4,21 |
|
3 |
024819000 |
CAP AE AX |
22µF |
500V |
|
C10,17,18 |
|
1 |
041589000 |
CAP AE AX |
47µF |
500V |
20% |
C15 |
|
1 |
028474000 |
CAP AE RDL |
100µF |
25V |
20% |
C14 |
|
2 |
028479000 |
CAP AE RDL |
220µF |
25V |
20% |
C29,30 |
|
2 |
028489000 |
CAP AE RDL |
470µF |
50V |
20% |
C27,28 |
|
1 |
039255001 |
CAP CA |
10PF |
100V |
LL |
C24 |
|
1 |
020909000 |
CAP CD |
47PF |
1000V |
10% |
C33 |
|
1 |
069724000 |
CAP CD |
100PF |
1000V10% C&F |
C2 |
|
|
1 |
020917000 |
CAP CD |
250PF |
1000V |
10% |
C25 |
|
1 |
020867000 |
CAP CD |
330PF |
1000V |
10% |
C20 |
|
1 |
017620000 |
CAP CD |
1500PF |
1000V |
10% |
C35 |
|
1 |
039265001 |
CAP CA |
2200PF |
100V |
LL |
C22 |
|
2 |
026202000 |
CAP PFF |
.0022µF |
600V |
|
C1,16 |
|
1 |
033581000 |
CAP PFF RDL .0033µF |
100V |
10% |
C26 |
|
|
1 |
033588000 |
CAP PFF RDL |
.01µF |
100V |
10% |
C31 |
|
2 |
024823000 |
CAP MPF RDL |
.01µF |
400V |
10% |
C6,34 |
|
1 |
036234000 |
CAP PFF RDL |
.015µF |
100V |
10% |
C12 |
|
4 |
024833000 |
CAP MPF RDL |
.022µF |
400V |
10% |
C8,9,11,13 |
|
1 |
024839000 |
CAP MPF |
.033µF |
400V |
|
C19 |
|
2 |
024853000 |
CAP MPF RDL |
.1µF |
250V |
10% |
C5,7 |
|
1 |
024855000 |
CAP MPF RDL |
.1µF |
630V |
10% |
C32 |
|
1 |
049402000 |
CONTROL 25K B SNAPIN |
|
|
R29 |
|
|
2 |
034719000 |
CONTROL 50KB SNAP IN |
|
|
R41,51 |
|
|
1 |
041913000 |
CONTROL SNAPIN 250K 10A |
|
R8 |
|
||
1 |
040985000 |
CONTROL SNAPIN 250K B |
|
|
R28 |
|
|
1 |
049401000 |
CONTROL 1M 10A |
|
|
R7 |
|
|
2 |
064089001 |
DIODE 1N4003 LL |
|
|
CR5,7 |
|
|
4 |
026730001 |
DIODE 1N4006 800V LL |
|
|
CR1,2,3,4 |
|
|
2 |
006260001 |
DIODE 1N4448 SIGNAL LL |
|
|
CR6,12 |
|
|
2 |
029690001 |
DIODE HV 3KV 200MA LL |
|
|
CR10,11 |
|
|
2 |
009165001 |
DIODE ZEN 1N4744A 15V 1W 5% |
|
CR8,9 |
|
||
16 |
025802000 |
FSTN TAB MALE .250X.032 PCB MT |
|
CP1-13,16-18 |
|||
2 |
031041000 |
FSTN TAB ML RTANG PCB .25X.032 |
|
CP14,15 |
|
||
2 |
025996000 |
FUSE CLIP PCB .250 & 5MM FUSE |
|
XF1 |
|
||
1 |
048827 |
FUSE QA 1-1/4X1/4 250V 2A |
|
F1 |
(100V/120V ONLY) |
||
1 |
020789 |
FUSE QA 20mmX5mm 250V 1 AMP |
|
F1 |
(230/240V EXPORT ONLY) |
||
1 |
016795 |
IC DUAL OP AMP TLO72 |
|
|
U1 |
|
|
1 |
030771 |
JACK 1/4 PCB 2/CD SCC |
|
|
J2 |
(SPEAKER JACK) |
|
1 |
027674 |
JACK 1/4 PCB 2/CD SCC INSL |
|
J3 |
(FOOTSWITCH JACK) |
||
1 |
037036 |
JACK PHONE PCB MONO CA PREMIUM |
J1 |
(INPUT JACK) |
|||
26 |
020888001 |
JUMPER WIRE 22GA .5" |
|
|
W1-26 |
|
|
1 |
048332 |
LED RED PNL MT 7" |
|
|
LD1 |
|
|
1 |
049305 |
PCB FAB BLUES JUNIOR |
|
|
(RAW BOARD) |
||
1 |
024947001 |
RES CF 1/4W |
5% |
47Ω |
LL |
R45 |
|
1 |
024964001 |
RES CF 1/4W |
5% |
280Ω |
LL |
R15 |
|
5 |
024969001 |
RES CF 1/4W |
5% |
1.5K |
LL |
R4,11,20,23,38 |
|
1 |
029005001 |
RES CF 1/4W |
5% |
2K |
LL |
R49 |
|
BLUES JUNIOR
|
|
PRINTED CIRCUIT BOARD ASSEMBLY (CONT) |
||||
QTY |
PART # |
DESCRIPTION |
|
|
|
REFERENCE DESIGNATION |
2 |
024977001 |
RES CF 1/4W |
5% |
4.7K |
LL |
R16,46 |
1 |
025942001 |
RES CF 1/4W |
5% |
7.5K |
LL |
R26 |
1 |
026510001 |
RES CF 1/4W |
5% |
9.1K |
LL |
R18 |
3 |
024981001 |
RES CF 1/4W |
5% |
10K |
LL |
R1,30,48 |
3 |
024987001 |
RES CF 1/4W |
5% |
22K |
LL |
R31,52,54 |
2 |
024989001 |
RES CF 1/4W |
5% |
33K |
LL |
R13,37 |
1 |
028153001 |
RES CF 1/4W |
5% |
75K |
LL |
R27 |
2 |
024997001 |
RES CF 1/4W |
5% |
100K |
LL |
R6,9 |
1 |
024998001 |
RES CF 1/4W |
5% |
120K |
LL |
R44 |
1 |
028955001 |
RES CF 1/4W |
5% |
130K |
LL |
R5 |
3 |
025059001 |
RES CF 1/4W |
5% |
220K |
LL |
R21,22,42 |
1 |
025061001 |
RES CF 1/4W |
5% |
330K |
LL |
R50 |
1 |
025828001 |
RES CF 1/4W |
5% |
430K |
LL |
R40 |
2 |
025065001 |
RES CF 1/4W |
5% |
470K |
LL |
R47,56 |
1 |
029618001 |
RES CF 1/4W |
5% |
910K |
LL |
R43 |
4 |
025069001 |
RES CF 1/4W |
5% |
1M |
LL |
R2,12,14,53 |
2 |
041741001 |
RES MOX FP 1/2W 5% |
47Ω |
|
R35,36 |
|
2 |
028580001 |
RES MOX FP 1/2W 5% |
100Ω |
|
R24,25 |
|
1 |
025829001 |
RES CF 1/2W |
5% |
150Ω |
LL |
R34 |
1 |
031065001 |
RES CF 1/2W |
5% |
91K |
LL |
R17 |
4 |
025116001 |
RES CF 1/2W |
5% |
100K |
LL |
R3,10,19,39 |
2 |
031067001 |
RES FILM 1W |
5% |
750Ω |
LL |
R57,58 |
2 |
027349001 |
RES FILM 1W |
5% |
10K |
LL |
R33,55 |
1 |
041258 |
RES CF 2W |
5% |
2.2K |
|
R32 |
1 |
028091 |
SWITCH PUSH SLFLK SHORT STROKE |
|
S1 |
||
5 |
029167 |
TUBE SOCKET 9 PIN PCB MOUNT |
|
XV1-5 |
||
1 |
014689 |
XSTR N-CH JFET J111 TO-92 |
|
Q1 |
||
|
|
CHASSIS ASSEMBLY |
|
QTY |
PART # |
DESCRIPTION |
REFERENCE DESIGNATION |
1 |
049307 |
CHS ASSY BLUES JUNIOR 120V |
(COMLETE CHASSIS) |
1 |
047560 |
BRACKET TUBE RETAINER PRO. JR. |
(@ V4,5) |
2 |
018022 |
BUSHING SNAP 5/16X17/32 BLK |
(@ OUTPUT TRANSFORMER) |
1 |
026116 |
BUSHING SR .500X.063X7/16 BLK |
(@ REVERB CABLE) |
1 |
026038 |
BUSHING SR. .625X.062X37/64BLK |
(@ POWER CABLE) |
1 |
010401 |
BUSHING SR .625X.125X37/64 WHT |
(@ 230V & U.K. POWER CABLE) |
1 |
026541 |
CABLE ASSY PWR W/.250 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 |
049101 |
CHS BLUES JUNIOR |
(RAW CHASSIS) |
6 |
041710 |
KNOB POINTED PUSH ON BLK |
|
1 |
027288 |
LENS LED RED |
(@ LD1) |
2 |
016352 |
NUT HEX 3/8-32X3/32 TK NI |
(@ SPEAKER & FOOTSWITCH JACK) |
9 |
097360 |
NUT HEX 4-40 EX LOCK |
(TUBE PCB MOUNT) |
4 |
022004 |
NUT KEPS #8-32 ZINC |
(POWER TRANSFORMER MOUNT) |
1 |
049102 |
PANEL FRONT BLUES JUNIOR |
(CHROME PANEL UNDER KNOBS) |
1 |
049300 |
PANEL REAR BLUES JUNIOR |
(@ BACK OF CABINET) |
9 |
031188 |
SCRW M 4-40X1/4 PHPS ZI W/WSHR |
(TUBE PCB TO CHASSIS MOUNT) |
4 |
038900 |
SCRW TF 6-32X1/4 PHP ZI |
(GND LUG & OUTPUT XFMR MOUNT) |
7 |
037353 |
SCRW TF 6-32X3/4 PHP ZI |
MAIN PCB TO CHASSIS MOUNT) |
2 |
039371 |
SPRING, EXTENSION 1.81X.15" |
(@ V4,5) |
9 |
038519 |
STANDOFF M/F 4-40 X 1/4L |
(TUBE PCB TO CHASSIS MOUNT) |
7 |
047040 |
STANDOFF NYLON PCB SNAPIN 1/2" |
(PCB MOUNT) |
BLUES JUNIOR
|
|
CHASSIS ASSEMBLY (CONT) |
|
|
QTY |
PART # |
DESCRIPTION |
REFERENCE DESIGNATION |
|
1 |
036570 |
SWITCH TOGGLE DPST W/NUTS |
S1 (POWER SWITCH) |
|
3 |
013341 |
TUBE 7025/12AX7WA RUSSIAN MADE |
V1,2,3 |
|
2 |
041255 |
TUBE 6BQ5/EL84 |
V4,5 |
|
2 |
990430092 |
WASHER FLAT .482X.709 NI |
(@ INPUT JACK & POWER SWITCH) |
|
2 |
990430010 |
WASHER LCK INTL 3/8X.681X.032 |
(@ SPEAKER & FOOTSWITCH JACK) |
|
1 |
049969 |
XFMR OUTPUT 15W |
T1 |
|
1 |
049967 |
XFMR PWR BLUES JUNIOR 120V |
T2 |
(120V ONLY) |
1 |
049968 |
XFMR PWR BLUES JUNIOR EXPORT |
T2 |
(100V,115V,230V,240V) |
|
|
CABINET ASSEMBLY |
|
QTY |
PART # |
DESCRIPTION |
REFERENCE DESIGNATION |
1 |
049103 |
CAB ASSY BLUES JR TWEED |
(COMPLETE CABINET) |
1 |
049103020 |
BACK ASSY BLUES JR TWEED |
(BACKBOARD) |
1 |
038566 |
CABLE ASSY SPKR RT ANG 13-1/2 |
(SPEAKER CABLE) |
1 |
022491 |
CLAMP CABLE NYL SCREW MNT 5/16 |
|
.3360 |
036131 |
CLOTH GRILLE VINTAGE TYPE |
|
4 |
029821 |
EYELET RFLNGD .215 OD X.315 L |
(REVERB PAN MOUNT) |
4 |
0415490 |
GLIDE PRESS-IN .75 DIA |
|
1 |
049103010 |
GRILLE BAFFLE ASSY BLUES JR |
(COMPLETE GRILLE) |
1048534 HANDLE 8 3/4" LEATHER BROWN
2036478 HANDLE CAP NI
1 |
041929 |
NAMEPLATE FENDER TWEED AMPS |
|
4 |
069393 |
NUT 6-32 HEX EXT LOCK |
(GRILLE MOUNT) |
4 |
021972 |
NUT T 10-32X3/4 STR 3 PRNG BLX |
(SPEAKER MOUNT) |
4 |
064162 |
NUT T 8-32X1/2 STR 3 PRNG BLX |
(HANDLE MOUNT) |
.0010 |
036650 |
PIN ESCUTCHEON #18X3/8 NI |
(NAMEPLATE MOUNT) |
1 |
028055 |
REVERB UNIT 800 OHM 8EB2C1B DN |
(PAN) |
4 |
026577 |
SCREW M 10-32X1 PHP BLX |
(SPEAKER MOUNT) |
4 |
036619 |
SCREW M 10-32X1-1/2 THP NI |
(CHASSIS MOUNT) |
6 |
015990 |
SCREW M 10-32X3/4 THP NI |
(BACKBOARD MOUNT) |
4 |
036618 |
SCREW M 6-32X1-1/2 OHP BRONZ |
(GRILLE MOUNT) |
4 |
026419 |
SCREW M 8-32X1 PHP STL NI |
(HANDLE MOUNT) |
5 |
029828 |
SCREW PB 8X3/4 PHP ZI |
(REVERB PAN & CABLE CLAMP MNT) |
1 |
037617 |
SPEAKER 12" 8 OHM 50 WATTS |
|
1.036 |
036343 |
TOLEX TWEED |
|
4 |
022327 |
WASHER FLAT 8X7/16 NI |
|
|
|
MISCELLANEOUS |
|
QTY |
PART # |
DESCRIPTION |
REFERENCE DESIGNATION |
1 |
049312 |
MANUAL OWNERS BLUES JUNIOR |
|
1 |
049302 |
SCHEM REDU W/SCV DIA BLS JR |
|
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