NuForce Ref 9 V2 User Manual

Nuforce V2 board upgrade (4/19/07)
This instruction is pertaining to the F15HER3D version of Nuforce V2 amplifier PCB
(Printed Circuit Board).
The upgrade is essentially a drop-in replacement of the existing 9.02 PCB (Printed
Circuit Board). On the V2 board all of the necessary power supplies (a separate power
supply for the input driver) are on the single PCB, therefore, the external 24V DC/DC
converter as part of the original SE package need not be used. A new Zobel Filter is
included for soldering to the speaker terminals.
The power supply (SMPS) should be upgraded as well to change Over-Current protection
threshold to 500W in order to reliability power-up the V2 boards.
Upgrade procedures for Ref 9 and Ref 9SE:
1. Unsolder the speaker cables and the output capacitor filter on the speaker terminals.
To prevent overheating the Eichmann binding posts, please connect a speaker cable to
the binding posts to serve as heat sink.
2. Unsolder and remove the input wires on the RCA and XLR.
3. Unplug the Red/Black DC power cable from the board. For the 9SE, remove all
other power wires as well (black, blue, and brown wires).
4. Remove the 6 screws on the PCB, and 3 heat sink screws on the bottom (use #3
Philips screwdriver bit) and remove 9.02 PCB completely. Use a paper tower to
clean up the heat sink compound on the heat sink and the bottom of the chassis. The
removed, functioning board should be kept as spare parts for Ref9/RefSE
replacement or repair.
5. On Ref9SE, an additional 100 Ohm resistor is required to be soldered between the
negative of the RCA (outer connection, i.e. shell) to the signal ground on the XLR.

NuForce Ref 9 V2 Specifications

General

Frequency Response	10 Hz - 50 kHz
Signal-to-Noise Ratio	> 100 dB
Input Impedance	47 kOhms
Gain	26 dB
Type	Class-D monoblock power amplifier

Summary

Nuforce V2 Board Upgrade Procedures

Speaker and Output Capacitor Removal

Unsolde r speaker cables and output capacitor filter. Use speaker cable as heat sink.

Input Wire Disconnection

Unsold and remove input wires from RCA and XLR connectors.

Power Cable Disconnection

Unplug Red/Black DC power cable. Remove other power wires for 9SE.

Original PCB Removal and Cleaning

Remove PCB screws and heat sink screws. Clean heatsink and chassis. Keep old PCB as spare.

Ref9SE Specific Resistor Installation

Solder 100 Ohm resistor between RCA negative and XLR signal ground on Ref9SE.

New V2 Board Installation

Install the new, slimmer V2 board. Connect green ground wire to a screw.

Heat Sink Mounting and Covers

Plug heat sink holes with nylon covers. V2 heatsink is not attached to chassis base.

Zobel Filter Installation

Install Zobel Filter under speaker terminal. Bend leads to touch solder tab. Do not solder yet.

Input Wire Soldering

Solder input wires (White, Red, Black) to V2 board and connectors as per color code.

Speaker Cable and Zobel Filter Soldering

Solder speaker cable and Zobel filter together. Keep speaker cable connected to prevent heat damage.

5V DC Power Wire Connection

Connect black wire near V2's DC input to 5V terminal. Connect 5V ground to 52V ground.

Main DC Power Cable Connection

Plug in the Red/Black DC power cable to the V2 socket. Cut relay wires on 9SE capacitor bank.

Final Connection and Functionality Check

Check all connections. Test amplifier by playing music. Check red LEDs and 5V/Ground.

Cover Reassembly

Be careful when closing cover due to heatsink contact for heat dissipation.

Increase Over Current Protection Threshold

SMPS Capacitor Modification

Add 50uF capacitor to SMPS power supply at IC3 Pin-4 and DZ2.