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Description microscope M695 Service manual M695
09/93 3077-HWE Doc code 636 718
Adjusting the lamp
brightness
Limiting the excess
current
A pulse-width modulator, dependent on the level of LAMP REF. controls the
final-stage transistors. The voltage is smoothed with chokes and electrolytic
condensers and the electricity is conducted to the lamp.
The secondary voltage is compared with the required value (LAMP REF) at
the entrance of the regulator.
The lamp current produces a voltage drop across resistor R9 in Lamp-Ground
(LGND). The regulator measures this voltage drop and limits the current to
5A during the final stage.