Usage; Trouble Shooting; No High Voltage; Irregular Crackling In The Loudspeaker - Velleman K4040 Manual

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USAGE

!
WARNINGS.
THIS UNIT GETS HOT, KEEP OUT OF REACH AND AWAY FROM CHILDREN.
CHECK THAT THE MAINS VOLTAGE CORRESPONDS TO THAT OF THE UNIT.
BEfORE OPENING THE UNIT, THE MAINS CORD MUST BE REMOVED IN ORDER TO AVOID
ELECTRIC SHOCKS.
It is normal for the tubes and cabinet to get very hot, so place the amplifier in a well ventilated area,
certainly not in a closed cabinet or rack.
We advise to check the standby current adjustment once a year, certainly if the end tubes are new. This
can easily be done by removing the front panel.
If the amplifier is not used for a short period of time, then set it to standby by putting the mains switch in the
middle position.

TROUBLE SHOOTING

No high voltage.

⇒ Check the transformer wiring.
⇒ Check the fuses.

Irregular crackling in the loudspeaker.

⇒ Replace R88 or R85 of the channel concerned.
A continuous buzzing in the loudspeaker (continuous oscillation of the amplifier) or crackling in bass peaks.
⇒ When using a piezo tweeter, a 10 Ohm resistor must be placed in series with the tweeter.
⇒ Increase R65 and R68 in value e.g. 1k or 1K5 (the input sensitivity will then be somewhat higher).
THE ABOVE ADJUSTMENTS SHOULD NOT BE DONE IN ANTICIPATION, ONLY IN THE EVENT OF
PROBLEMS AND AFTER HAVING THOROUGHLY CHECKED ALL COMPONENTS, CABLING AND
SOLDERING.
NOTES:
As tubes are very sensitive to shocks, do NOT move the unit when the tubes are hot.
Should a tube nevertheless fail, then this can be seen by the sudden bright red glow of the lamp. In the
event of the lamp discharging, then the associated anode resistance of 10 Ohm will almost certainly be
defective, also check the 220 Ohm resistors, R63, R64, R66 and R67.
ATTENTION: Should the amplifier not work, just send it to us so that we can check it. Please only send
the MAIN PCB !.
If you decide to send the complete unit, you MUST order a special protective shipping box (order
code DM4040) from you distributor. If not then the unit will surely be damaged during transport and
it will suffer damage beyond repair.
Velleman Kit can never be hold responsible for damage during transport!
Happy listening.
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