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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. Or try another cable.
2. No sound or one channel missing
Have you selected the right input?
Are all the connections OK?
Are the speakers connected at both ends?
Is everything switched on?
Is the "standby" switch down?
If you have tried everything and the meter light is
working and the heaters are glowing either the left or
right internal fuses may have blown. There is a single
fuse for the left pair of 300Bs and one for the right pair of
300Bs looking from the front.
In that case there would be "0" bias reading for that
channel. (It is extremely unlikely that both internal fuses
would have blown).
Check the bias reading for the valves on that channel. If
there is no reading, the likely cause is the internal fuse.
There are two spare HT ceramic fuses taped to the
bottom plate. Ideally these should be replaced by a
qualified person, but if this is not possible follow these
instructions.
1. Disconnect mains lead for 10 minutes.
2. Number and remove 300Bs and 6SN7s.
3. Invert amplifier and remove bottom plate.
4. Replace fuse for suspect channel (test old fuse if
possible).
5. Re-assemble amplifier by reversing the procedure.
6. Switch on and check the bias for that channel.
Should the fuse blow again or the fault remains switch
off and refer to your dealer or Icon Audio.
The correct fuses are available from Icon Audio free of
charge (postage payable outside the UK).
Distorted sound.
One channel or both? Try another source; if sound
improves then it's probably something wrong with the
first source. If there is no improvement and you know it is
not the loudspeakers, if so it could be an amplifier
problem but it is unlikely to affect both channels.
You can usually find the problem is by swapping
connections over. And swapping Left input with Right.
Hum Adjustment
Will only need doing if replacing the 300Bs. The
filaments are heated by AC. This causes hum to be
introduced into the circuit which can be eliminated by the
hum adjustment adjacent to each pair of 300Bs.
Method. If a meter which reads AC at 1-10mV is
available connect to the loudspeaker terminals with the
5 Trouble Shooting
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 set at "zero". Only a small adjustment
should be necessary.
Other Causes of hum/noise.
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/noise, 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.
4. Intermittent noise on one channel such as rustling,
crackling, hiss etc may be due to a 6SN7/CV181
valve. The valve may be identified by swapping
valves from left to right. This is occasionally a poor
pin contact, rocking the valve gently may prove this,
in which case clean the pins, otherwise the valve
should be replaced.
Interference Problems
This amplifier design is 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
interference is normal for up to 1-2 meters away.
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 relatively
low current all of the time. Therefore we would
suggest for use of more than 3 hours per day replace
the valves every 5 years. This excludes filament and
other failures which happen randomly. The small
valves sometimes "go noisy". Valves may be
returned to Icon Audio for free testing. They should
be well packed.
Service: Should you suspect a problem, you could
return the unit to Icon Audio or one of our agents for
a periodic service or repair. If you are outside the UK
contact Icon Audio.
Mains Supply
This amplifier is hard wired to work on 230/240v AC
(or 117v US). The transformer may be re-configured
by an engineer for 117v ac. Contact for information.
will
often
cure
this.
Mobile
phone
Page 6
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