Philips PM2519 - Page 43

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3. CHECKING AND ADJUSTING
WARNING: Before switching-on, ensure that the instrument has been installed in accordance with the
instructions outlined in Section 4 of the Operating Manual.
The opening of covers or removal of parts, except those to which access can be gained by hand
is likely to expose live parts, and accessible terminals may also be live.
The instrument shail be disconnected from all voltage sources before any replacement or
maintenance and repair during which the instrument will be opened.
ff afterwards, any adjustment, maintenance or repair of the opened instrument under voltage
conditions is inevitable, it shall be carried out only by a skilled person who is aware of the
hazard involved.
Bear in mind that capacitors inside the instrument may still be charged even if the instrument is
separated from all voltage sources.
The tolerances in this chapter correspond to the factory data, which only apply to a completely re-adjusted
instrument. These tolerances may deviate from those mentioned in the Technical Data. (Chapter 1 of the
Service Manual).
For a complete re-adjustment of the instrument the sequence in this chapter should be adhered too.
When individual components, especially semi-conductors are replaced, the relevant section should be
completely re-adjusted.
To calibrate this measuring instrument, only reference voltages and measuring equipment with the required
accuracy should be applied. If such equipment is not available, comparative measurements can be made with
another calibrated PM 2519. However, theoretically in extreme cases, the tolerances may leave some room
for doubt.
The measuring arrangement should be such that the measurement cannot be affected by external influences.
Protect the circuit against temperature variations (fans, sun).
With all measurements, the cables should be kept as short as possible; at higher frequencies co-axial leads
should be used.
Non screened measuring cables may acts as aerials so that the measuring instrument could measure LF voltage
values or hum voltage.