PLEASE READ THE INSTRUCTIONS
FULLY BEFORE COMMENCING
KIT CONTENTS. POWER SUPPLY, 4 WAY TERMINATED CABLE, RUBBER GROMMET, HEAT SHRINK, IEC MAINS LEAD.
TOOLS REQUIRED. SOLDERING IRON, PLIERS, M3/4 ALLEN KEY, SCREW
DRIVER, SOLDER, ELECTRIC DRILL, 10mm DRILL BIT.
DISCONNECT THE AMPLIFIER FROM THE MAINS BEFORE BEGINNING. If the unit
has been used recently, allow sufficient time for the power supply
capacitors to discharge before beginning (5 mins is usually sufficient).
This is a two stage conversion. Stage 1 disables the on-board
high voltage supply and connects the new off-board supply. Stage
2 enables the new supply to switch on and off from the amplifier.
Remove the amplifier lid.
The power supply components are located on a PCB on the left
hand side of the chassis. Locate the 47R resistor nearest to
the Bridge Rectifier BR1 and remove it. Cut the two (red?) wires
that come from the mains transformer to the Bridge BR1 and insulate
them using the heat shrink provided. Drill a 10mm hole in the
back or bottom of the amplifier, fit the rubber grommet and feed
in the umbilical cable. Connect the RED wire
to the +ve terminal of C2 and the GREEN wire
to the -ve terminal of C2.
This completes Stage 1.
DANGER: The two Red wires
carry high voltage AC. Make sure they are fully insulated.
The large mains transformer on the left of the chassis has a
winding marked either 0-3.15-6.3 or 3.15-0-3.15. Bare back the
insulation on the two outside terminals and solder the BLUE
wire to one terminal and the YELLOW wire to
the other. DO NOT REMOVE OR DISTURB ANY OTHER CONNECTIONS
TO THESE POINTS. This completes Stage 2.
Dress the new cables tidily and replace the lid. Connect the
newly installed umbilical lead to the off-board supply. Replace
the mains leads to both units. Switch on the amplifier as usual.
Your amplifier should now be ready to play. The valve supply
will take longer to come up to operating voltage than the old
supply but this will have the advantage of lengthening the life
of the valves.