Panasonic KX-TA1232 Service Manual page 30

since feed back is not done on the primary side from +15 V line. So, the chopper regulator, IC450
and the circuit around it stabilize +15 V. The following is the roles of main surrounding circuit.
D452, C454, C455: Rectifier and smoothing circuit
L450: For preventing resonance
R456, C459: For compensating phase
R457: For detecting an electric current
L451, C460: Filter
L454, C467: Filter
-15 V Circuit
The circuit connected pin 8, 9-10 of switch transformer T400 generates -15 V. With feed back on
the primary side from -15 V line, -15 V is stabilized by the oscillation control of the primary side.
The following is the roles of main surrounding circuit.
D451, C450: Rectifier and smoothing circuit
D450, Q450, C452: Feed back circuit
PC400, R451, R454,
VR450, R453,
L453, C468: Filter
+5.3 V Circuit
+5.3 V is generated from the chopper regulator, IC451 connected to the +15 V output. It has an
over voltage protection circuit to prevent abnormal output voltage. The following is the roles of
main surrounding circuit.
L452: Filter
R460: Electric current detection resistor
F401, SCR401: Over voltage chopper circuit
D453, R466: Over voltage detection circuit
R467, C465
Bell Amp Circuit
It increases bell signals sent from CPU board in Power Op. Amp, IC452 and sends them into the
bell amp. Then, they are sent to the extension boards.
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