us the key in order to begin to look for the problem, saving us time and unnecessary efforts.
Keep in mind when remove an element of the main board, that it is double layer
printed circuit, because of what the components PADs goes joined of one layer to another one
through a metal tube (VIA), because of what could not do much strength for if pulled up the
VIA. This is important mainly in components that have many pins (integrated circuits, connec-
tors, etc.), for which it is recommended to have a good desoldering station.
Next they are detailed some fails, so that the personal technical qualified could try to
repair them:
1) If a fuse break because of a mains transitory, change it (keeps in mind of changing it
for the correct for the mains voltage at which it is working. For more information reviews the
section changing the fuse, placed on page 6 of this manual). If it breaks again, checks the
overvoltage protections placed in the voltage selector. If they are broken, substitute them by
equivalent (VARISTOR of 130 volts).
2) If fails the power supply, the unit will remain in MUTE mode. In this case it is neces-
sary to check the bridge (D64), the filters capacitors (C111, C112, C120 and C121) and the regula-
tors (U44 and U51). Keep in mind that if the unit has been turned on, the radiators of the regu-
lators could be hot, with the rising danger of burns.
Once changed the element damaged, it is necessary to verify that no element is over-
heating in the main board, since being is able to this element causes the break in the power
supply.
3) The potentiometers have a half life, they could dirty and produce noise upon moving
them. It is important that you don't use sprays cleaners over the potentiometers, since they
shorten the half life of these, in order to clean them use compressed air.
In order to change a potentiometer, it is necessary to remove the top and bottom
covers of the crossover (be careful with the bottom cover, since its join with the toroidal trans-
former), the frontal and the panel behind it. In order to remove the frontal, extracts the four
visible screws, and a nut behind the subfrontal (be careful with this nut since is difficult see it).
The panel behind the frontal is join to the chassis by four screws located in the chassis side,
and by the potentiometers. Upon introducing the frontal again, be careful with the LEDs, since it
is necessary to introduce them in the frontal and it is a delicate operation.
4) Normally the signal reductions in the crossover are produced by three causes: the
LEVEL potentiometers, the unbalanced circuit and the electronic balanced circuit. In the unbal-
anced and electronic balanced circuits, normally the signal reduction that takes place is of 6
dBv (half of the signal). The LEVEL potentiometers could give rise to signal reductions or in-
creases, as well as to swinging signals.
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