Page 1
KXR 100
KEYBOARD EXTENDED RANGE
SERVICE MANUAL
CONTENTS:
Notices
Specifications
Theory of Operation
Parts lists:
Preamp
Power Amp
Chassis assembly
Cabinet assembly
Miscellaneous
Schematics/diagrams
Fender Musical Instruments Corp. 7975 North Hayden Road Scottsdale, AZ 85258
Page 2
KXR 100
(This is the model name for warranty claims)
KEYBOARD EXTENDED RANGE
SERVICE MANUAL
FEBRUARY 1995 REV A
TYPE PR262
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
Page 3
KXR 100
SPECIFICATIONS
Part Number: 120V Version : 22-8501
230V Version : 22-8561
Power Amp Section
Power output: 80 Watts RMS
Sensitivity: 370mV RMS
Input impedance: 33K Ω
Rated Load Impedance: 4 ohms
Distortion at rated power: Less than .1% @ 1kHz, before compression
Less than 1% @ 1kHz, maximum compression
DELTACOMP™ range: 20dB
PREAMP SECTION:
Input Impedance: XLR – 10k Ω
¼” phone – 36 k Ω
Sensitivity for 80 watts: XLR – 2.8 mV
CHANNEL and MASTER ¼” phone – 28mV
VOLUME at maximum
all tone controls at “0”
Equalization Range: Low +/- 12dB at 100Hz
Low Mid +/- 12dB at 338Hz
High Mid +/- 12DB at 1588Hz
High +/- 12dB at 4 kHz (shelving)
Dimensions: Height:27 1/2" (69.8 cm)
Width: 20 1/2 " (52.1 cm)
Depth: 12" (30.5 cm)
Weight: 55 lbs. (25 kg)
Product specifications are subject to change without notice
Page 4
KXR 100
THEORY OF OPERATION
The Channel One input will accept a Balanced or Unbalanced signal via a ¼” Phone plug or a 3 pin XLR
connector. U1B provides a gain of 1 for the ¼” input, and a gain of 10 for the XLR input. A balanced low
level microphone connected to Channel One, allows the KXR 100 to function as a small self contained
Vocal and Instrument PA system. U1B also rolls off high frequencies at about 128kHz.
Located within the negative feedback loop of U1A is the Channel One Volume control. It provides a
minimum gain of 1, and a maximum gain of 15. At maximum gain, Capacitor C6 rolls off the high
frequencies at about 47kHz. Channel’s Two and Three do not offer a low level XLR input Jack. They do
offer a function that shorts across the Volume control via a switch contact in the ¼” input jack. This causes
U2A and U3A to remain locked into a Unity Gain mode, disabling the Volume control, until a plug is
inserted into the jack. This reduces noise in the input circuitry.
The three channels sum together and feed the Reverb Drive stage U4A and the Summing Amp U5A. U4B
senses the return signal from the Reverb Pan. R70 and C47 provide a slight boost in the high frequencies,
R29 and C20 roll off low frequencies. This produces a fairly bright reverb sound. To eliminate noise, C49
limits the high frequency response to about 5kHz. All ground connections in the Reverb circuitry are routed
through a dedicated trace to the Star Ground point on the circuit board. This eliminates any bleed through
of noise into other audio ground paths.
U5A sums the dry signal with the Reverb return signal and then drives the Equalizer circuit. Gyrators U6B,
U7B, and U7A are used for the low (100Hz), Low Mid (338Hz), and High Mid (1588Hz)bands. The High
band uses a single pole shelving filter (R47, C34) at 4kHz. U6A performs the Boost/Cut function, and also
drives the Effects Loop.
The Effects Loop Send is capable of providing a pseudo balanced signal if desired. This helps to reduce
hum. The Effects Loop Return will accept an Unbalanced or Balanced input.
U5B drives the Record Out jacks, and the Master Volume control. R55 and C40 boost the low frequencies
at 220Hz. This boost is not desired at the Record Out jacks. Therefore C41 and R56 remove the Low
boost. This allows the Record Out to see the same signal as the input channels, plus any tone shaping
from the Equalizer. Between the ouptput of U5B and the Master Volume control, C43 and R60 boost high
frequencies. The boost in Low and High frequencies provide a Smile Curve response.
The signal and ground line from the Master Volume control feed through a Flex Jumper to U2A, which is on
the Power Amp circuit board. Any Hum induced into the signal and ground line is canceled by the
Common Mode Rejection at U2A.
Using R71 and C60, U2A provides the high frequency pre-emphasis from about 1kHz on up. This prevents
compressor “pumping” caused by very low frequencies. The increase in high frequencies prevents
repetitive releases by the compressor when triggered by low frequencies. De-emphasis occurs just prior to
the speaker connections, on a small break-away circuit board that contains R72, R73, and C61.
Page 5
KXR 100
THEORY OF OPERATION (CONT)
Deltacomp
U2B is a unity gain amplifier that drives the power amp stage, and U3. U3 is an Operational
Transconductance Amplifier (OTA). In conjunction with U2B, it acts as the gain reduction circuit for the
Deltacomp. The attack/release circuit for the Deltacomp contains the diode, resistor, and capacitor
network that drives the base of Q8. Comparator U4A senses the output of the power amplifier. As the
amplifier approaches clipping, the output of U4A toggles negative. The negative voltage charges
capacitors C22 – C25 all at once in parallel as a one-pole filter through a single time constant made up with
R47. [R47 x (C22+C23+C24+C25)]=2.2k x 8.8uF=19.4mSec.
As the capacitors charge, the negative voltage at the base of transistor Q8 turns on this Darlington device.
Current flows from the collector of Q8 to pin 5 of U3. This current controls the output amplitude of U3. The
inverted output from U3 mixes with the signal at the input of U2B (pin 5) causing cancellation, which
reduces the input to the power amplifier. This prevents the amplifier from clipping. When the output of the
power amplifier is reduced, the comparator toggles positive, removing the negative control voltage from the
attack/release circuit. The blocking action of diodes CR24 – CR27 force capacitors C22 – C25 to
discharge (release) through a 4-pole filter with different time constants, through resistor R46.
Turn-On delay
JFET Q7 and associated components provide a 2 – 3 second turn-on delay for the audio input to the power
amplifier. Upon power-up, capacitor C21 charges through resistor R40. The negative gate voltage pinches
off the JFET, removing the ground from the input of the amplifier. When switching the power off, C21
immediately discharges through diode CR23, grounding the input of the amplifier. TROUBLESHOOTING
TIP: Check for proper operation of this circuit when experiencing excessive turn-on or turn-off “pops”, or
no output when signal is appliied to the input. Many times the JFET itself can be the culprit. NOTE:
Excessive turn-off “pops” can also be caused by uneven discharge of the +/- power supplies. Usually a
mismatch in the filter capacitors will cause this problem. It’s easy to look at both supplies on an
oscilloscope. Invert one scop input and check for even discharge to zero volts.
U1 is a high-voltage op-amp that provides voltage gain for the power amplifier. Bootstrap capacitors C1
and C2 sense the output through R6. This provides more voltage swing for the op-amp with respect to
ground.
Diodes CR5 – CR8 (BYV26D) make up the fixed bias circuit for the output transistors. The bodies of the
diodes mount through the heatsink to properly track the temperature of the transistors. These diodes were
selected because they exhibit a 2mV decrease in knee voltage for every 1 degree (Celsius) increase in
temperature. Pin 6 of U1 is at 0Vdc. Therefore the bias diodes provide 2 voltage drops (1.2V) to the base
of Darlington transistors Q1, Q2, Q5, Q6.
Diodes CR32 – CR35 make up a voltage clamp protection circuit. If the bases of the output transistors
reach 4.5 volts with respect to the output, the diodes will turn on, clamping the voltage.
The output signal feeds through the Headphone Jack to the 1kHz de-emphasis circuit, before driving the
15” speaker and dual piezo horn.
Page 6
KXR 100
PARTS LIST
PREAMP PRINTED CIRCUIT BOARD ASSEMBLY
QTY PART # DESCRIPTION REFERENCE DESIGNATION
1 047755 PCB ASSY KXR 100 PREAMP (STUFFED)
1 047974 CABLE RIBBON ASSY 9 CKT 8 INCH (@P1,95)
2 038690 CAP AE AX 1.0UF 100V C20,28
3 038692 CAP AE AX 10UF 35V C48
17 009512 CAP AE AX 22UF 25V 20%
14 039256 CAP CA 68PF 100V C3,4,6,9,10,12,15,16,18,23,24,27,38,39
1 038703 CAP CA .1uF 50V C30
1 039270 CAP CA 10000PF 50V 5% C34
1 039266 CAP CA 3300PF 100V C19
2 039262 CAP CA 680PF 50V C33,49
1 033586 CAP PFF RDL .0068uF 100V 10% C31
1 033590 CAP PFF RDL .022uF 100v 10% C41
2 033591 CAP PFF RDL .033UF 100V 10% C43,40
1 033592 CAP PFF RDL .047UF 100V 10% C47
1 036234 CAP PFF RDL .015UF 100V 10% C29
1 038656 CONTROL 10KB R31 (REVERB)
1 038716 CONTROL 2K B SNAP IN R61 (MASTER)
4 038655 CONTROL 50KB W/ CD R36-39 (@ EQUALIZER)
3 037323 CONTROL SNAPIN 50K 15A R8,16,24
4 025802 FSTN TAB MALE.250X.032 PCB MT CP1-4
7 016795 IC DUAL OP AMP TL072 U1-7
6 031570 JACK PHONE PCB STEREO PREMIUM J1,3-6,8 (INPUTS EFF LOOP)
1 025933 JACK PHONO DUAL PC MT J7 (RECORD OUT RCA’S)
2 048466 JACK RCA SINGLE PCB MOUNT J9,10 (REVERB IN/OUT)
1 029177 JACK XLR FM PC MNT J2 (INPUT #1,3 PIN)
23 020888 JUMPER WIRE 22GA.5X.175 W1-20,22-24
1 028039 LED RED 5X5MM SLB-55VR3 LD1
1 047754 PCB FAB KXR 100 PREAMP (RAW CIRCUIT BOARD)
2 024937
1 024942
1 024952
1 024965 RES CF 1/4W 5% 1K R29
2 031819 RES MF 1/4W 5% 1.82K R3,4
10 024971 RES CF 1/4W 5% 2.2K
3 024972 RES CF 1/4W 5% 2.7K R42,44,46
1 029610 RES CF 1/4W 5% 3K R47
1 028861 RES CF 1/2W 5% 3.3K
2 024977 RES CF 1/4W 5% 4.7K R57,58
2 024986 RES CF 1/4W 5% 18K R40,35
16 031818 RES MF 1/4W 1% 18.2K R1,2,5,6,10,11,13,14,18,19,21,22,51,25,53,54
2 024987 RES CF 1/4W 5% 22K R33,55
1 024989 RES CF 1/4W 5% 33K R56
3 024993 RES CF 1/4W 5% 47K R28,30,34
8 024997 RES CF 1/4W 5% 100K R12,20,32,41,43,45,48,59
4 029722 RES FILM 1W 5% 1K R64,65,66,67
2 028045
1 9904701440 SPACER LED.7X.125BLUE
RES CF 1/4W 5% 10Ω
RES CF 1/4W 5% 22Ω
RES CF 1/4W 5% 100Ω
RES FILM 1W 5% 220Ω
C1,2,5,7,8,11,13,14,17,21,22,25,26,35,36,37, 42
R68,69
R26
R70
R7,9,15,17,23,25,27,49,50,60
R100
R62,63
POWER AMPLIFIER PRINTED CIRCUIT BOARD ASSEMBLY
QTY PART # DESCRIPTION REFERENCE DESIGNATION
1 047764 KXR 100 PCB ASSY POWER AMP (STUFFED)
1 038690 CAP AE AX 1.0uF 100V C14
9 028459 CAP AE RDL 2.2uF 50V 20% C15-17,19,21-25
1 038692 CAP AE AX 10uF 35V C7
2 028465 CAP AE RDL 22uF 25V 20% C5,6
5 028471 CAP AE RDL 47uF 50V 20% C1,2,10,11,28
Page 7
KXR 100
POWER AMPLIFIER PRINTED CIRCUIT BOARD ASSEMBLY (CONT)
QTY PART # DESCRIPTION REFERENCE DESIGNATION
2 031756 CAP AE 4700uF 50V C12,13
3 027278 CAP MPF .1uF 63V 10% C3,4
1 041501 CAP MPF AX 2.2uF 100V 10% C61
1 024854 CAP MPF RDL .1uF 400V 10% C46
1 033578 CAP PFF RDL .001uF 100V 10% C20
1 033580 CAP PFF RDL .0022uF 100V 10% C60
1 033591 CAP PFF RDL .033uF 100V 10% C18
2 064089 DIODE 1N4003 CR21,22
13 006260 DIODE 1N4448 SIGNAL CR1,2,23-29,32,35
4 029045 DIODE 6A 400V 6A4 LEAD FORMED CR17-20
4 028776 DIODE BIAS BYV26D LEAD FORMED CR5-8
2 027329 DIODE ZEN 1N5228B 3.9V 5% CR33,34
2 028119 DIODE ZEN 1N5353B 16V 5W 5% CR13,14
2 026000 FSTN TAB MALE PCB MT.187X.032 CP7,12
16 025802 FSTN TAB MALE.250X.032 PCB MT CP1-6,1-11,17-22
2 025996 FUSE CLIP PCB.250 & 5MM FUSE XF1
1 039982 FUSE QA 1-1/4X1/4 250V 4A F1 (100/120V ONLY)
1 020794 FUSE QA 20mmX5mm 250V 2A F1 (230/240V ONLY)
1 027418 HDR, 1CTR 9 CKT SQ PIN P1
1 027404 IC CA3080AE QTA U3
2 016795 IC DUAL OP AMP TL072 U2,4
1 028047 IC OMP AMP MC1436/SG1436Y U1
4 040903 INSULATOR MICA TO-218 @Q1,2,5,6
23 020888 JUMPER WIRE 22GA W1-22
1 047763 PCB FAB KXR 100 PWR AMP (RAW CIRCUIT BOARD)
1 040716 PLATE COUPLER HEATSINK
1 024952
5 024965 RES CF 1/4W 5% 1K
2 024971 RES CF 1/4W 5% 2.2K R38,47
1 024973 RES CF 1/4W 5% 3.3K R71
2 024977 RES CF 1/4W 5% 4.7K
1 024979 RES CF 1/4W 5% 6.8K R36
4 024981 RES CF 1/4W 5% 10K R35,49,50,52
1 024987 RES CF 1/4W 5% 22K R34
7 024989 RES CF 1/4W 5% 33K R29-33,48,51
2 024993 RES CF 1/4W 5% 47K R7,25
1 024998 RES CF 1/4W 5% 120K RR41
2 025069 RES CF 1/4W 5% 1M R39,40
2 025942 RES CF 1/4W 5% 7.5K R9,10
4 028990 RES CF 1/4W 5% 51K R43-46
2 028029 RES FILM 1W 5% 1.5K R1,21
1 028045
2 028030
2 048894
1 048468
4 028028
1 048467
4 027638 SCREW TF 4-40X3/8 HWHS ZI.1” HD @Q1,2,5,6
4 032908 SCRW TF 6-32X3/8 PHP ZI (PCB TO HEATSINK MOUNT)
1 028503
4 028169 WSHR SHLDR NYL 5/32X1/4 @Q1,2,5,6
1 014689 XSTR N-CH JFET J111 TO-92 Q7
2 028114 XSTR NPN TIP 142 T-218AC Q1,5
1 014408 XSTR PNP MPSA63 TO-92 Q8
2 028115 XSTR PNP TIP 147 TO-218AC Q2,6
RES CF 1/4W 5% 100Ω
RES FILM 1W 5% 220Ω
RES FILM 1W 5% 680Ω
RES WW 10W 10% 220Ω
RES WW BT 10W 10% 47Ω
RES WW BT 5W 10% .47Ω
RES WW BT 5W 10% 39Ω
THERMISTOR 10Ω 5W C60-11
R37
R8,11,24,26
R42,58
R6
R4,5
R22,23
R72
R2,3,18,19
R73
TH1 (220V/230V/240V ONLY)
Page 8
KXR 100
CHASSIS ASSEMBLY
QTY PART # DESCRIPTION REFERENCE DESIGNATION
1 048510 CHS ASSY KXR100 (COMPLETE CHASSIS)
1 007565 BUSHING SR.625X125X37/64 BLK (@ PWR CABLE 100/120V ONLY)
1 040401 BUSHING SR.625X.125X37/64 WHT (@PWR CABLE 230/240V ONLY)
1 026527 CABLE ASSY PWR 120V.187 TABS (POWER CABLE 100/120V ONLY)
1 026528 CABLE ASSY PWR 230V .187 TABS (POWER CABLE 230V ONLY)
1 036479 CABLE ASSY PWR AUST. .187 TABS (PWR CABLE 240V AUSTRALIA)
1 040992 CABLE ASSY PWR 5A U.K. .187 TAB (PWR CABLE 240V U.K. ONLY)
1 047758 CHS KXR 100 (RAW CHASSIS)
1 028560 END BELL XFMR 85W (TRANSFORMER MOUNT)
9 048357
4 023591 NUT ACORN 8-32 (TRANSFORMER MOUNT)
1 047759 PANEL FRONT KXR 100 1
1 047660 PANEL REAR KXR 100
1 9904101560 SCRW 6X3/8 HI-LO PHP BLX (RCA JACK MOUNT)
12 017433 SCRW M 6-32X3/8 PHP BLX (PCB TO CHASSIS MOUNT)
2 031868 SCRW PLASTITE 4X1/4 (XLR JACK MOUNT)
1 041595 SCRW TF 6-32X3/16 [J[ ST; ZO SE,S (@ GROUND LUG)
4 027636 SCRW TF 8-32X5/8 HWH BLX (HEATSINK TO CHASSIS MOUNT)
1 025935 SWITCH DPST .187 TAB S1 (100/120V ONLY)
1 039287 SWITCH DPST .187 TAB GLOBAL S1 (230/240V EXPORT ONLY)
4 030007 WSHR LCK INTL 8X.330X.02 ZI (TRANSFORMER MOUNT)
1 027668 XFMR PWR 120V 85W T1 (DOMESTIC 120V ONLY)
1 039357 XFMR PWR EXP DELUXE 112 T1 (100/115/230/240 ONLY)
KNOB CUSTOMER BLK/OFF WHT 180
°
CABINET ASSEMBLY
QTY PART # DESCRIPTION REFERENCE DESIGNATION
1 047757 CAB ASSY KXR 100
1 047120 CABLE REVERB 1450MM
1 022491 CLAMP ABLE NYL SCRW MNT 5/16
REF 026317 CLOTH GRILLE BLACK PBC
6 031867 CORNER 2 HOLE W/NOTCH BLK PWDRD
2 031840 CORNER 3 HOLE BLK PWDRD
4 029821 EYELET RFLNGD .215 OD X.315 L (REVERB PAN MOUNT)
1 028885 GASKET HORN DUAL PIEZO
4 027849 GLIDE CAB 1/24X.335 BLX WAX (NO INSERT)
1 047757 GRILLE ASSY KXR 100 (COMPLETE GRILLE)
2 048958 HANDLE RECESSED (NEW STYLE ON EACH SIDE OF CABINET)
2 031845 HANDLE CAP 2 HOLE BLK PWDRD (OLD STYLE ON TOP)
1 025884 HANDLE INSERT 7.78” (OLD STYLE) (SPRING STEEL)
1 025883 HANDLE SHORT NO LOGO (OLD STYLE) (NO INSERT)
1 028813 HORN DRIVER DUAL PIEZO
4 019275 INSERT GLIDE CUSHION 1.27 DIA (RUBBER ONLY)
1 011298 NAMEPLATE FENDER SMALL (LOGO)
1 031669
8 026577 SCRW M 10-32X1 PHP BLX (SPEAKER MOUNT)
4 017441 SCRW M 10-32X1-1/2 OHP STL BLX (HANDLE MOUNT, OLD STYLE)
4 036199 SCRW M 8-32X1-3/16 OHP BLX CP (CHASSIS MOUNT)
5 029828 SCRW PB 8X3/4 PHP ZI (REVERB PAN MOUNT)
2 018113 SCRW SMA 4X1/2 OHP BLX (NAMEPLATE MOUNT)
14 026576 SCRW SMA 8X5/8 THP BLX (HORN/CORNER MOUNT)
8 016627 SCRW SMA 8X5/8 THP BLK (HANDLE MOUNT/NEW STYLE)
4 017942 SCRW WOOD 8X1 FHP BLX (GLIDE MOUNT)
1 040580
4 029527 WSHR FNSH 8-5/8 FLNGD BLX WX (CHASSIS MOUNT)
REVERB UNIT 800 Ω 8EB2C1D
SPEAKER 15” 4Ω 100W
(MOUNTED INSIDE CABINET ON BOTTOM
BENEATH INSULATION)
MISCELLANEOUS
1 047761 MANUAL OWNERS KXR 100
1 047752 SCHEM REDU KXR 100
1 047753 SRVC DIAG KXR 100 W PWR AMP
Page 9
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