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
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 (*) 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 |
Part Number:
Power Amp Section Power output: Sensitivity:
Input impedance: Rated Load Impedance:
Distortion at rated power:
DELTACOMP™ range:
PREAMP SECTION:
Input Impedance:
Sensitivity for 80 watts: CHANNEL and MASTER VOLUME at maximum all tone controls at “0”
Equalization Range:
Dimensions:
Weight:
KXR 100
SPECIFICATIONS
120V Version |
: |
22-8501 |
230V Version |
: |
22-8561 |
80 Watts RMS
370mV RMS 33K Ω
4 ohms
Less than .1% @ 1kHz, before compression Less than 1% @ 1kHz, maximum compression 20dB
XLR – 10k Ω
¼” phone – 36 k Ω
XLR – 2.8 mV
¼” phone – 28mV
Low |
+/- 12dB at 100Hz |
Low Mid |
+/- 12dB at 338Hz |
High Mid |
+/- 12DB at 1588Hz |
High |
+/- 12dB at 4 kHz (shelving) |
Height:27 1/2" |
(69.8 cm) |
Width: 20 1/2 " |
(52.1 cm) |
Depth: 12" |
(30.5 cm) |
55 lbs. |
(25 kg) |
Product specifications are subject to change without notice
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.
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