Fender Super Champ-XD User Manual

Fender Super Champ XD >> DSP (Digital) Board Bypass Instructions
PLEASE READ EVERYTHING ENTIRELY BEFORE YOU START!
This instruction is designed to modify a Fender Super Champ XD amplifier such that the DSP
board will be eliminated from the circuit. Typically, it would apply in those cases where trouble
with the digital portion of the amp is experienced yet the remainder (analog/tube portion) is
working. But, before blaming the digital board, it is good practice to verify that the tubes are good
or there is not some other problem such as a disconnected speaker wire or blown fuse.
Although I modified a Super Champ XD, other amps (such as the Vibro Champ XD) may be good
candidates for this modification as well.
Understand that what is being accomplished here is to (1) bypass the DSP (digital) board and (2)
create a tone control (unfortunately, the factory tone adjustment was handled in the DSP board).
To accomplish this, R84 (“GAIN”) and R85 (“VOLUME 1”) are re-purposed.
See Appendix 1 - Schematic.
When completed, the procedure described below will allow you to adjust VOLUME and
BRIGHTNESS (TONE) – nothing else! It assumes that you want to retain the “tube amp” sound
and that any added effects will be inserted between the instrument output and the amp input.
See Appendix 2 – Frequency Response Data to see the effect of the Brightness Control.
I accept no responsibility in the outcome of your project (since you are the one doing it), but I am
confident that if you follow these directions studiously, you will end up with a reliable great Fender
tube amp!
If you should have questions, comments, or you have adapted this procedure to another amp,
please email me at: dbtech@brasherweb.com
This procedure expects the technician to have good workmanship/soldering skills and the
necessary tools to work on printed-circuit assemblies and leaded parts, including
low/medium power soldering iron and heat gun. Additionally, a Dremel type cutting tool or
X-Acto type knife is required. An ohm-meter/multimeter is desirable.
Please be safe and wear protective eyewear!
PARTS LIST:
1 ea. 10,000 ohm, ⅛, ¼, or ½-watt resistor
1 ea. .03 micro-farad (µF) capacitor, 100 VDC or more – can be fabricated and material is not
important. Below are examples of two combinations that may be used:
A) Use a .01 µF and a .02 µF (100V or more each), see Figure 10a
B) Use three .01 µF (100V or more each), see Figure 10b
C) Any other combination that is equivalent to .03 µF total at 100V or more
1 ea. 4.7 or 5.0 µF capacitor, 100 VDC or more
1 ft. 24 or 26 gauge hookup wire (color not important; I used blue)
1 ft. Heat shrink tubing (HST), size 3/32” or 1/8”
3 tie wraps or some lacing twine
Label maker (if you want to re-label front-panel controls)
STEP-BY-STEP INSTRUCTIONS:
NOTE – where the cutting of PCB traces is indicated, use a Dremel type tool or an appropriate X-
Acto type knife and blade.

Fender Super Champ-XD Specifications

General

Type	Hybrid
Power	15 Watts
Preamp Tubes	1 x 12AX7
Power Tubes	2 x 6V6
Inputs	1 x 1/4"
Speaker	10" Fender Special Design Speaker
Channels	2
Effects	Reverb, Delay, Chorus
Outputs	1 x 1/4"
Dimensions	17.5"
Weight	24 lbs

Summary

Modification Overview and Safety

Purpose and Scope

Explains bypassing the DSP board and creating a tone control for the Fender Super Champ XD amplifier.

Prerequisites and Tools

Details required technical skills, tools like soldering iron, heat gun, and multimeter for the modification.

Safety Precautions

Emphasizes the importance of reading instructions and wearing protective eyewear before starting.

Parts and Materials List

Resistors and Capacitors

Lists required resistors (10k ohm) and capacitors (.03uF, 4.7/5.0uF) with voltage ratings.

Wiring and Hardware

Specifies hookup wire, heat shrink tubing, tie wraps, and optional label maker.

Step-by-Step Modification Procedure

Initial Disassembly and Board Preparation

Instructions for unplugging power/speaker, removing chassis, and orienting the circuit board.

Trace Cutting for R85 and R84

Detailed steps on cutting PCB traces around R85 (VOLUME) and R84 (GAIN) as per schematic.

Ribbon Cable Modification

Guidance on cutting and insulating specific conductors (#1, #2, #3, #8) on the ribbon cable.

Wiring Connections to P5

Describes connecting wires and components to specific pins (P5 pin 11, 5, 13, 1) on connector P5.

Wiring Connections to R85

Details the wiring steps for connecting components to terminals A, B of R85 and R52.

Wiring Connections to R84

Details the wiring steps for connecting components to terminals A, B, and C of R84.

Finalizing Wiring and Reassembly

Instructions for capacitor connections, securing wires, and reassembling the chassis into the cabinet.

Appendices

Appendix 1: Schematic

Provides a schematic diagram illustrating the modified circuit with red indicators for changes.

Appendix 2: Frequency Response Data

Presents measured frequency response data for the amplifier in FLAT and BRIGHT modes.