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length of yellow/green striped wire and 2 female push-on terminals. Make sure you solder both ter-
minals. (See fig 5)
• Mount the top cover on the enclosure (Make sure the earth lead of the vertical plate is bent down, so
it does not get squeezed between the lid and the enclosure). Use the supplied black button head
hexagon socket screws.
• Mount the front panel. Use the supplied right angle mounting brackets, together with the shakeproof
washers and the M3 and M4 bolts. Take care of the correct position of the mains switch and LD2.
• Make sure everything fits well, and tighten all screws.
THIS AMPLIFIER RUNS HOT, OPERATE IT OUT OF THE REACH OF CHILDREN !
REMOVE THE MAINS PLUG AND WAIT AT LEAST 15 MINUTES BEFORE REMOVING THE
SOME PARTS MAY CARRY DANGEROUS VOLTAGES, EVEN WHEN THE UNIT IS UNPLUGGED
TROUBLESHOOTING
Hum coming from the speakers :
To make sure the amplifier is the source of hum, short the RCA input (by means of a spare male RCA
plug, which you short internally), and disconnect the earth connector SK21.
As a reference, listen at about 1m (3 ft) from the speaker, there should be an negligible amount of hum
present.
If there's still a reasonable amount of hum present, check the bias current of every valve. Also check
the electrical connection between the PCB ground and the enclosure, which is done trough the bolt next
to R1.
A defective valve can also be a source of hum.
If hum is only present, when the amplifier is hooked up to an audio system, then a hum-loop could be
the cause. To verify if this is the case, disconnect SK21
Use good quality, as short as possible, interconnecting leads.
For best results, choose equal lengths for both left and right amplifier.
If the high tension is not present, check the transformer wiring and the mains fuse, located at the back of
the unit, below the mains inlet.
An intermitted crackling sound coming from the speakers could point to a defective resistor R62.
Replace it with the same value and power rating.
A continuous buzzing sound coming from the speakers or a crackling sound during bass peaks could be
caused by oscillation of the amplifier.
In this case, try raising the value or R46 (e.g. 2K7 or even 3K3). This will also slightly increase the input
sensitivity.
If your speaker system includes a piezo driver, make sure it has a 10 ohm/ 1W resistor in series with the
unit.
THE MODIFICATIONS MENTIONED ABOVE ARE ONLY TO BE PERFORMED WHEN REPEATED
INSPECTION OF THE CIRCUIT BOARD, SOLDER JOINTS AND WIRING DID NOT POINT TO ANY
OBVIOUS FAULTS OR MISTAKES OF ANY KIND.
CHECK YOUR MAINS VOLTAGE
MAKE SURE IT MATCHES THE SELECTED VOLTAGE
!
COVERS
25
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