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5 Trouble Shooting
1. Amplifier Dead
Check the power fuse 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 bade 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 contact you dealer or Icon
Audio. Replace with the same type Available from Icon
Audio free in the UK (outside the UK you must pay
postage).
The fuse in the power cord plug (if any) should be a 5
amp fuse, although unlikely, this should be checked if
the amplifier fuse is OK.
2. No sound
Have you selected the right input? Are the connections
OK? Is everything switched on? Are the speakers
connected?
Is the amp in “standby”?
If you think you have tried everything and the meter light
is working and the heaters are glowing either or one of
the internal fuses may have blown. They are located
inside the amplifier and should be replaced by a
competent engineer. Replacements free on request from
Icon Audio. Contact us or your dealer for further
guidance. If a second fuse blows the amplifier needs
service.
Distorted sound.
One channel or both? Try another source; if sound
improves then it’s probably something wrong with the
first source. If no improvement try different speakers, if
no improvement could be an amplifier problem. If one
channel try swapping the input cables over if the
distortion does not move could be an amplifier fault. If so
double check by swapping the speaker cables over If
fault moves to the other speaker this will confirm an
amplifier fault. It fault does not move this would indicate
a speaker problem.
Hum Problems and Changing Valves.
The 300B filaments are heated by AC. This causes hum
to be introduced into the circuit so with “push-pull” the
hum of one valve is adjusted to balance out the hum of
the other valve of the push-pull pair. This does not
normally require adjustment but when the valves are
changed you may notice an increase in low level hum,
requiring the following adjustment to be made. If a meter
which reads AC at 1-10mV is available connect to the
loudspeaker terminals with the loudspeaker still
connected and adjust for minimum hum. Normally this
would be 1-2mV.
Alternatively, this could be done with one person making
the adjustment and another listening closely to the bass
speaker for minimum hum. The volume should be at
“zero”. Only a small adjustment should be necessary.
Other Causes of hum.
1. Establish if the hum is internal or external to the
amplifier. If the hum disappears with no inputs connected
the problem is with the source and/or interconnects.
2. If the amplifier has serious hum, this may be a fault.
Contact your dealer or Icon Audio.
3. Hum Loop. If the hum is only on one input, you may
have a “hum loop” caused by too many “ground” or
“earth” connections. A possible 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
or worse.
Interference Problems
This amplifier design is very resistant to mains-born
interference. But some heating systems, fridges,
cookers etc. can generate RF (radio frequency)
interference which travels through the air (and walls).
Although rare this can be very irritating. Relocating
the equipment will often help. Or a simple suppressor
capacitor will often cure this. Mobile phone
interference is normal for up to 1-2 meters away.
One channel missing.
Usually ‘bad’ connection on either the input or the
speakers. Try swapping the connection over to
establish if the problem is caused by:
(a) An input to the amplifier:
Sound will move to the other channel.
(b) The amplifier or speakers.
Sound will not move.
(c) Consider checking internal fuses (see 5.2).
Strange noises coming from speakers:
Turn volume to minimum on unused input, if problem
corrected either fault with source unit or with
connection. If noise persists, problem with 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. A valve that is hot is not a guarantee that it is
working properly; conversely a valve that is not hot
will not be working (usually cold to the touch).
“Rustling” and “crackling” noise is often due to the
smaller valves, which if at low level if at a low level is
nothing to nothing to worry about.
Valve Life and Replacement
Valve life will depend upon such things as hours of
use and number of on/off cycles, Do not switch on
and off unnecessarily (see
Standby).
The 300B
valves are operating in “CLASS A/B” mode (approx.
5 Watts output) which means they are using
moderately high current all of the time. Therefore we
would suggest for use of more than 3 hours per day
replace the valves every 5 years.
If using expensive 300Bs the valve life may be
extended by running the 300Bs at a lower HT to give
around 20 Watts output. Icon Audio or most
engineers will be able to do this.
Service:
Should you suspect a problem, you could
return the unit to Icon Audio for a periodic service or
return the valves for testing free of charge. Carefully
remove the valves, hold by the base when removing,
to prevent damage Make sure they are numbered so
they 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
(or 117v US). The transformer may easily be re-
configured for 110/120v ac. Contact for more
information.