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Old 10-17-2020, 10:11 AM   #21
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Default Re: Samsung Syncmaster 245b BN44-00195A

ICP801S (TDA4863) VCC is on PIN8. It gets that voltage from the M_VCC line. QB802 is the regulator/switch for this voltage. The source of the voltage is from TB801S,pin5, this is rectified by DB803 and filtered by CB806. The voltage at this point should be around +25vdc.
When pc801S is turned on by ON/OFF, Pin4&3 supply the +25v to the base of QB802 turning it on, the voltage on QB802 is set by ZDB805 + DB804 This will result in about +16vdc on QB802 emitter.

P6KE300A is a spike suppressor diode and not for supplying vcc voltage
The VZ is the internal zener diode for protection on the vcc line, The VCC for the ic to turn ON is minimum 12.5vdc, I suspect it operates around 16VDC, If the VCC drops to 10vdc the ic will turn off.

Last edited by R_J; 10-17-2020 at 10:29 AM..
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