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Replacement of Components and Parts
For the replacement of parts and components use only
parts of the same or equivalent type. Resistors without
specific data in the diagrams have a power dissipation of
0,33 Watt and a tolerance of 1 %. Resistors in the high volt¬
age
circuit
must
have
sufficient
electric
strength.
Capacitors without a voltage value must be rated for an
operating voltage of 63V. The capacitance tolerance should
not exceed 20%. Many semiconductors are selected,
especially the gate-diodes 1N4154, and all amplifier transis¬
tors, which are contained in push-pull circuits (including the
FETs). If a selected semiconductor is defective, all gate-
diodes or both push-pull transistors of a stage should be
replaced by selected components, because otherwise
there are possibly deviations of the specified data or func¬
tions. The FIAMEG Service Department can give you advice
for troubleshooting and replaceable parts. Replacement
parts can be ordered by letter or telephone from the nearest
FIAMEG Service Office. Please supply the following infor¬
mation: Instrument type and serial number, description of
the part (including function and location in the instrument),
quantity desired.
Replacement of the Power Transformer
Should it be necessary to replace the mains/line trans¬
former, the correct terminal sequence (color identification)
for primary and secondary windings must be followed (see
diagram "Power Supply" and the figure below). In addition,
the relevant Safety Regulations must be observed. Here,
we refer only to those requirements relative to the parts
conductively connected to the supply mains:
- The construction of the instrument shall be such as to
prevent any short-circuiting or bridging of the insulation,
clearances or creepage distances between those parts
connected to the supply mains and any accessible con¬
ductive parts due to accidental loosening or freeing of
the wiring, screws, etc.
- The rigidity of the mains wiring connections, which may
be subject to mechanical stresses, shall not be depend¬
ent upon the soldering alone. To meet this requirement,
the bare ends of the wires must be pushed through the
holes in the respective soldering tab, bent over with a
pair of pliers, and subsequently fixed by soldering.
- The minimum cross section of the protective earth con¬
nection between the instrument's power inlet and the
connecting soldering tab on the rear chassis must be
0.81 mm^ in North America and 0.75 mm^ in Western
Europe. The connecting soldering tab on the rear chassis
has to be secured mechanically against loosening (e.g.
with lock washer).
After replacing the power transformer, all remaining bits of
wire, solder and other foreign matter must be removed
from the PCBs, the vicinity of the power transformer and
from within the insulating connecting box by shaking,
brushing and blowing. Finally, the top plate of the insulating
connecting box has to be replaced. Before connecting the
instrument to the power supply, replace the possibly defec¬
tive fuse, press the
POWER
button and make sure that
there is an adequate insulation state between chassis (=
safety earth conductor) on the one hand, and the live/line
pin as well as the neutral pin, on the other. Only after proper
insulation has been established may further function tests
with open chassis follow, but with appropriate precaution¬
ary measures.
Rear View of Power Switch and Appiiance
Iniet with Voitage Seiector and Fuse
Adjustments
As advised in the Operating, Test and Service Instructions,
small corrections and adjustments are easily carried out
with the aid of the Circuit Diagrams and
Adjusting Plan.
However, a complete recalibration of the scope should not
be attempted by an inexperienced operator, but only some¬
one with sufficient expertise. Several precision measuring
instruments with cables and adapters are required, and only
then should the pots and trimmers be readjusted, provided
that the result of each adjustment can be exactly deter¬
mined. Thus for each operating mode and switch position,
a signal with the appropriate sine or square waveform, fre¬
quency, amplitude, risetime and duty cycle is required.
Subject to change without notice
S3 203-7
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