ALLEN&HEATH
WARNING – HIGH VOLTAGES
Power Supply Unit (PSU) work should only
be carried out by qualified personnel.
We recommend that you use an approved Allen & Heath
service centre for all power supply work.
Please contact your local Allen & Heath distributor for more details.
http://www.allen-heath.com/
SECTION C
POWER SUPPLY
CAUTION !
C
TO AVOID DAMAGE TO INTERNAL COMPONENTS BY MISHANDLING AND/OR
MISCONNECTION, ONLY TECHNICALLY COMPETENT PERSONNEL SHOULD
ATTEMPT SERVICE WORK ON THIS UNIT.
ANY SERVICE WORK SHOULD BE UNDERTAKEN ONLY AFTER DISCONNECTING
THE MAINS SUPPLY LEAD FROM THE POWER SUPPLY UNIT.
L2dSM2
Section C - 1
ALLEN & HEATH
TECHNICAL DESCRIPTION
The power supply for the GL2000 range is internal to the console and is mounted on a steel sub-chassis.
INSTALLATION
An important consideration when positioning the console is the need for natural convection of air flow over the whole
unit. Good ventilation, in the floor and back of the console, will ensure a path for continuous air flow. Pay particular
attention to the ventilation around the power supply unit which is mounted off the rear connector panel. The GL2000
can be operated as a free standing unit without requiring any special cooling arrangement, but should not be covered
in any way. Always stand the unit on a firm flat surface well away from any soft furnishings.
THE POWER SUPPLY AND CONSOLE EARTHING
The GL2000 power supply is a linear power supply which, like other linear supplies, produces DC voltages by
rectifying, smoothing and regulating AC voltages from the secondary windings of a mains transformer. The console
connects directly to the local AC mains supply and provides the regulated DC operating voltages required by the
GL2000 console. The console chassis is always connected to mains earth. Audio 0V connects to the console chassis
internally. Should problems be encountered with ground loops operate the audio ground lift switches on other
equipment connected to the console or disconnect the cable screens at one end. Refer to the section on 'EARTHING'
in the User Guide. This is to avoid earth loops in situations where multiple earth paths are present.
THE CHASSIS METALWORK IS ALWAYS CONNECTED TO MAINS EARTH VIA THE EARTH WIRE IN
THE MAINS PLUG. DO NOT REMOVE THE EARTH WIRE CONNECTION IN THE MAINS PLUG !
CONNECTING AC MAINS TO THE CONSOLE
Mains input to the GL2000 is via a standard 3 pin IEC mains input connector. A mains cable with moulded mains plug
suitable for the local supply is supplied.
Check that the voltage indicated in the fuseholder window is the same
F
as the mains supply in your area.
AC mains supply = 100 to 110 V.AC 100 T 1.6A 20mm fuse
F
F
ALLEN & HEATH
AC mains supply = 110 to 125 V.AC 120 T 1.6A 20mm fuse
AC mains supply = 210 to 230 V.AC 230 T 630mA 20mm fuse
AC mains supply = 235 to 260 V.AC 240 T 630mA 20mm fuse
To avoid the risk of fire replace the fuse only with the correct type and
value as specified on the unit.
Always switch the unit off before connecting or disconnecting the
console power cable.
Section C - 2
L2dSM2
SPECIFICATION
AC MAINS INPUT: 100V, 110V, 120V, 220V, 230V or 240V @ 50Hz to 60Hz single phase
POWER CONSUMPTION: 60VA
DC OUTPUT: +48V @ 100mA, +/- 16V @ 0.8A per rail. (GL2000-424)
NOISE & RIPPLE: < 2mV max (peak to peak)
SERVICE ACCESS
Any fault condition, with the exception of simple mains fuse failure due to underrating or an unusual mains input
condition, will require removal of the base cover to enable correction of the fault. This is achieved using a cross-head
screwdriver to remove all of the base screws which are positioned along the edges of the base. Do not forget to remove
the two screws in the centre rear of the base.
Carefully lift the cover and place it to one side. The power supply sub chassis can then be removed by unsrewing the
2 mounting screws (A) in the console rear panel and the 2 fixing screws (B) in the sub chassis base next to the PSU
circuit board. Take care not stretch the wires connected to the console.
Servicing Components
All of the regulators are in TO220 packages. To replace them, it will be necessary to remove the power supply circuit
board assembly with the heatsink attached. Refer to the L2D PSU assembly diagram 002-150.
1.) Remove the 4 PCB mounting nuts (C) and 2 heatsink fixings (D).
2.) Carefully lift the heatsink and PCB assembly clear of the PSU sub chassis and unscrew the screw and nut
of the regulator IC that requires replacing. Take care to retain the small insulating bush beneath the head
of the screw and the insulating SIL pad under the regulator.
3.) Rotate the assembly to gain access to the solder side of the PCB and desolder the three terminals attached
to the regulator. The regulator can now be removed.
4.) Fit the replacement regulator by first fixing it to the heatsink using the screw and nut and then soldering the
three terminals to the circuit board. Make sure the insulating SIL pad and bush are fitted. The metal tab at
the top of the package is electrically connected to the centre lead and correct insulation is essential. If the
insulating SIL pad between the regulator and the heatsink looks damaged then it should be replaced before
installing the new regulator. Note that the regulators rely on good thermal contact with the heatsink to
dissipate heat, and this is provided by the SIL pad.
5.) Reassemble the circuit board and heatsink assembly into the power supply sub chassis. Check your work
and remove any debris from the sub chassis before refitting it to the console.
CAREFULLY CHECK ALL WIRING CONNECTIONS AND ENSURE THAT THERE ARE NO LOOSE
PARTS LYING AROUND INSIDE THE CONSOLE.
A
D
D
A
L2dSM2
B
B
console inverted with the base removed
C
C
Section C - 3
ALLEN & HEATH
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