CX335 User Manual v1.0
14
Appendix
Changing the AC Voltage setting
IMPORTANT:
This procedure should be not be attempted by
anyone who is not competent to solder/desolder
small components from printed circuit boards. If you are not
suitably experienced, please refer this procedure to qualified
service personnel.
1. Unplug all rear panel connectors (including AC mains)
2. Remove the six pozidrive screws securing the top panel,
and remove the panel.
3. Identify and remove four M3 screws on the PCB. With
the front panel nearest you, these are located as follows:
i. Just behind the THRESHOLD control
ii. Just behind the GAIN REDUCTION meter
iii. Immediately in front of the mains transformer
iv. Immediately behind the mains transformer
4. Turn the unit over. Remove the seven pozidrive screws
securing the bottom panel, and remove the panel.
Remove the white insulating card from the PCB in the
region of the mains switch and transformer (this is held
in place with a double-sided adhesive pad).
5. Turn the unit the right way up again. Note the shorting
link(s) immediately adjacent to the mains transformer.
If the unit is set for 230 V operation, one link will be
present; if it is set for 115 V operation, two links will be
present.
6. To convert the CX335 from 230 V to 115 V operation,
or vice-versa, desolder the existing link(s) and replace it/
them in the alternative positions. A desoldering tool, a
small soldering iron and a pair of snipe-nosed pliers is
required for this operation.
7. Turn the unit over again, and replace the insulating
card on the underside of the PCB. Ensure that the two
circular holes are aligned with the holes in the PCB.
Replace the bottom panel and secure with the screws
removed in Step 4.
8. Turn the unit the right way up, and replace the four M3
screws removed in Step 3.
9. Replace the top panel and secure with the screws
removed in Step 2.
Refer to the fuse data on page 8. Change the mains fuse
to one of the correct rating for the new voltage setting.
EMC considerations
The CX335 Compressor-Limiter fully conforms to the
relevant electromagnetic compatibility (EMC) standards
and is technically well behaved. You should experience no
problems interfacing it to other items of equipment and
under normal circumstances, no special precautions need
to be taken. If the CX335 is to be used in close proximity
to potential sources of HF disturbance such as high power
communication transmitters, radar stations and the like, it is
recommended that balanced input and output connections
are employed (with balancing transformers if the outputs/
inputs of the other equipment are unbalanced), and that
all signal leads are kept as short as possible. If the CX335
is mounted in a 19” rack, do not locate the unit in close
proximity to a powerful amplifier of any kind, which may
radiate a strong magnetic field from the power transformer.
Earthing
When several mains powered units are connected together
via their signal cables, there is a risk of one or more earth
loops, which may cause an audible hum on the system
even with gain set to minimum. The 0 V rail of the CX335
is coupled to the chassis ground by a parallel resistor/
capacitor network and no interconnection problems should
be encountered, but if there is any hum or other extraneous
noise when source equipment is connected, the situation can
generally be remedied by observing the following guidelines:
•
Always connect to sources and destinations using
balanced connections wherever possible. Note that, for
EMC reasons, cable screens should be connected at both
ends.
•
Use audio isolating transformers (readily available from
trade suppliers) at the inputs if necessary. These will
ensure that the amplifier is electrically isolated from the
source equipment.
The signal source units should be located as close as possible
to the amplifiers and the metal housing of the various units
should not be electrically connected together through the
equipment rack. If this is a problem, rack isolating kits are
available from specialist hardware suppliers. If the problem
persists, try to connect all interconnected units, including
power amplifiers to a common power source to ensure a
common ground is provided.
