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Circuit Descriptions
12-1) POWER BUS
This POWER BUS, and SMPS (Switch Mode Power Supply), is an improved efficiency power- convertion circuit for
converting AC input voltage to high voltage DC. However, a consistent attention should be paid to the POWER BUS
because 115V AC and 170V DC may be generated. The voltage input has AC applied into BD1(Rectifier Circuit) through
FUSE(F1) and LF1, and smoothes the rectified voltage through C101(180uF/450V). As a result, DC voltage is
applied into the SMPS TRANS. At the same time, the rectified DC voltage is applied into No 2. of U5(TOP246Y)08
through R24 and R25, and starts initial IC operation. With the role of SNUBBER Circuit (D1, R18, C7, TVS1, C8), also
controls the switching wave-formed P-P voltage to protect U5 IC. R21(2W470K) is the parts that special regard must be
paid to the safety against potential electric shock during SVC, which is charged with power ON and discharging
electricity with power OFF. When the initial operating voltage is applied into U5 No.2 PIN, the U5 IC starts high speed
(130KHz) switching operation. And then the input voltage is applied into NP1 (primary winding) of TRANS first,
and a voltage proportional to
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