Philips PM 5131 Gerätehandbuch Seite 51

42
4.4,
4.4.1.
4.4.2.
4.43.
4.4.4.
4.5.
4.5.1.
SAFETY INSPECTION AND TESTS AFTER REPAIR AND MAINTENANCE
IN THE PRIMARY CIRCUIT
General directives
— Take care that creepage distances and clearances have not been reduced
— Before soldering, wires:
should be bent through the holes of solder tags, or wrapped round the tag in the form of an open
U, or, wiring ridigity shall be maintained by cable clamps or cable lacing.
— Replace all insulating guards and -plates.
Safety components
Checking the protective earth connection
The correct connection and condition is checked by visual control and by measuring the resistance
between the protective-lead connection at the plug and the cabinet/frame. The resistance shall not be
more than 0.5 2. During measurement the mains cable should be moved. Resistance variations indicate
a defect.
Checking the insulation resistance
Measure the insulation resistance at U = 500 Vdc between the mains connections and the protective lead
connections. For this purpose set the mains switch to ON. The insulation resistance shail not be less
than 2 MQ.
Note:
2 MQ. is a minimum requirement at 40 °C and 95 % relative humidity. Under normal conditions the
insulation resistance should be much higher (10 to 20 MQ2).
SPARE PARTS
General
Standard Parts
Electrical and mechanical parts replacement can be obtained through your local Philips organisation
or representative. However, many of the standard electronic components can be obtained from other
local suppliers. Before purchasing or ordering replacement parts, check the parts list for value, tolerance,
rating and description.
NOTE:
Physical size and shape of a component may affect instrument performance, particularly at high fre-
quencies. Always use direct-replacement components, unless it is known that a substitute will not degra-
de instrument performance.
Special Parts
In addition to the standard electronic components, some special components are used:
~ Components, manufactured or selected by Philips to meet specific performance requirements.
— Components which are important for the safety of the instrument, marked with 'S' in the parts list.
ATTENTION:
Both type of components may only be replaced by components obtained through your local Philips
organisation.