Caution – HT instruments HT5 User Manual

Page 8

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EN - 7

5.2. LAMP


The HT5 allows you to quickly detect the presence of faults in lamps, especially for all gas-
filled low pressure and high pressure vapour lamps.

Measurement procedure:

• connect test probe (see Fig. 1 – point 1) to glass body or lamp socket

• Press “Test” button (see Fig. 1 – point 5) for the duration of the test


Do not touch the lamp socket (this could lead to faulty test results).

Testing Fluorescent Tubes
If the fluorescent tubes are lit during lamp tester check but do not work when installed, the
spiral-wound filament or the ballast may be faulty. Filaments and ballasts can be tested
using the built-in continuity tester (see § 5.3)


Only check ballasts and capacitors when they are disconnected from live
circuits and when capacitors have been discharged. These conditions have to
be verified by measurements.

Testing low pressure sodium vapour tubes
Test tube by contacting the socket pins with test probe and observe if the inner tube is
glowing. In some cases, only part of the tube is glowing. The other part should be lit when
the test probe touches the second pin.

Testing high pressure sodium vapour tubes
Touch tube with test probe. A clear, blue line within the arched tube indicates that the tube
is in perfect condition. Any other test results indicate a defective tube.

Testing Neon Tubes
Touch tube or socket with test probe and press button Test. The tube has to be replaced if
no illumination is visible.

Testing mercury vapour and metal halogen lamps
Touch tube socket with test probe and press button Test. The arched tube is defective if
there is no constant glowing. If the tube only operates when not installed and goes on and
off or seems unstable within the lamp holder, verify if the lamp holder or the lamp are
subject to unusual or extreme heat. Unusual or extreme heat can result in repeated
opening and closing of the thermal tube switch.