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'Burning in'
Although the amplifier should sound good within
about 15 mins it can take up to an hour to sound
at its best when new and will take several months
of regular use before it is fully 'run in'. Like the
ageing of wine, the biggest change occurs in the
first month but continues at a slower and slower
rate for 2-3 years. The sound will become more
mellow and musical over time.
Upgrading Valves!
Quality valves should sound better and have a
better service. The valves supplied with selected
models are the result of careful comparison with
1. Amplifier Dead
Check the 2 amp mains fuse in the IEC socket at the
back of the amplifier. To gain access, remove the mains
lead. The fuse is in a small plastic drawer, which forms
part of the socket assembly. To open insert a flat blade
screwdriver or similar and prise open. The fuse in use
is the innermost the outer is a spare. Should the
replacement fuse also blow there is a fault you should
disconnect from the mains and seek qualified help or
Icon Audio. Replacements should be 2 Amp 'anti-surge'.
The fuse in the wall plug should be a 5 amp fuse,
although unlikely to fail, this should be checked if the
amplifier fuse is OK.
2. No sound
Have you selected the right input? Is the "Tape Monitor"
switch on? Are all the connections OK? Is everything
switched on? Are the speakers connected?
Distorted sound.
Could be your source, the speakers or the amplifier,
check all wiring, and try swapping things around to
eliminate or prove which component if the problem.
Left or right amplifier? If both probably the source unit.
Try another source. If one amplifier is distorted check the
bias. No bias reading means either a fuse blown or a
faulty valve. Distorted sound at higher volumes may be
because one of the KT120 valves failing. A symptom of
this could be unable to bias properly. Refer to an
engineer or to Icon Audio.
3. Hum Problems
If you experience hum, try disconnecting the input, if it
clears it is NOT the amplifier, but some cause external to
the MB30m and further advice should be sought from
your dealer or Icon Audio. By elimination find out which
unit is causing this. Interconnects MUST be well
screened (some exotic ones are not!).
If hum persists with no input this is may be a fault.
4. External hum causes;
Identify which input is causing hum. Connect one input at
a time. A common cause is a 'hum loop' caused by
having too many earths, and may be identified by
unplugging each input source from the mains. One
remedy for this is to use an interconnect which only has
the screen connected at one end. Other causes of low-
level hum can be from adjacent equipment, so
experiment with moving equipment around to see if this
makes
the
hum
better
interconnects WILL cause hum with this amplifier. Only
use screened interconnects.
Never disconnect a mains earth. It is there for your
protection!
*See engineers notes at rear
5 Trouble Shooting
or
worse.
"Unscreened"
other makes. But beware of paying a premium for
"New Old Stock" valves where you may be paying
for rarity value and not performance. Icon Audio
can recommend and supply a range of standard
and upgrade valves. Importantly valves supplied
will be tested and listened to before despatch so
you can be sure of the best sound quality.
Cabinet Care
To remove dust we suggest gentle brushing of the
paintwork with a soft paintbrush. Other marks can
usually be removed with a damp cloth. Never use
anything wet on the amplifier, and always clean
with the power disconnected.
5. Strange noises coming from speakers
Disconnect the pre-amplifier. If the noise disappears
the fault is elsewhere. Turn volume to minimum on
unused pre-amplifier input, if the noise disappears,
the fault is with the source or the connection. If noise
persists, the problem is with the pre-amplifier.
If a whole output valve glows red (other than the
heater), often accompanied by a hum through the
speakers, switch off immediately, and refer to Icon
Audio or a service engineer, as this could be valve
failure.
6. Service: Should you suspect a problem, you could
return the unit to your dealer or Icon Audio for a
periodic service or return the valves for testing free of
charge. You should carefully remove the valves (by
pulling the base, not the glass). Numbering them with
a marker from left to right as you do so in order that
that may be replaced in the same position. They
should be well packed in cardboard & foam or
similar, and returned to Icon Audio for testing.
(Valves are very rugged if packed properly).
*Mains Supply
This amplifier is hard wired to work on 230/240v ac.
The transformer may be re-configured for 110/120v
ac by a qualified engineer. See engineers notes or
contact Icon Audio for more information.
This manual is provided for guidance only, and is not
intended as a comprehensive service manual. In
case of problems you should refer to your dealer or
directly to Icon Audio.
Page 6
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