Description Of Fst 2 Leak Tester; Explanation Of The Controls And Displays - HEIDENHAIN PWM 8 Operating Instructions Manual

9. Description of FST 2 Leak Tester

The leak tester serves to check NC-linear encoders and rotary encoders with sinusoidal output signals and
9-pin connector for leak circuits (up to 3 MΩ) at the cabling and the photocell board.
The FST2 is switched on automatically as soon as a test piece (e.g. a linear encoder) is connected. The
current conduction through the lamp (LED) of the encoder is used for testing. When testing equipment
without a lamp (e.g. an extension cable or if the lamp is defective) the automatic test is not active. In this
case the button "Start man." must be pressed.
Encoders with integral pre-amplifiers can only be tested for leak circuits between internal shield ( ) and
external shield( ).
Owing to the internal resistance of the pre-amplifier (< 3 MΩ) the remaining 4 LEDs always indicate a leak
circuit when a test unit is connected.

9.1 Explanation of the Controls and Displays

1 Input socket, 9-pin:
For connection of measuring systems with sinusoidal output signals and extension cables with 9-pin
connector.
2 Manual start button:
When testing equipment without lamp/LED or encoders with defective lamp/LED the manual start button
must be pressed to activate the FST2. The leak tester is then active as long as the button is pressed.
The manual start button also serves to test the battery. The battery voltage is in order,
if the LEDs light up in a sequence like a running light as long as the button is pressed.
3 LED display:
Leak circuits are displayed by permanently lit LEDs. The LED running light indicates that there is no leak
circuit in the test piece.
The figure on the FST2 housing indicates the location of the leak circuits.
4 Brief operating instructions
Brief operating instructions in German are printed on the rear side of the leak tester.
A sticker in English language is supplied with FST2.
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