SAMSUNG KS-1A CHASSIS TV USES IC SPM802ER / SPM 802ERN MICROCOMPUTER JUNGLE [NO POWER]
As set is dead, troubleshooting must start with main power regulator section.
The main power switching IC used with these sets is [KA 500765]. Only two output voltages are taken out from SMPS transormer. 112VDC and 16VDC.
Check the mains fuse.
If found blown out, check [CX801S-0.22MFD] and overvoltage protector SNR [YX 815-SVC7510-10A]. to this model set, even the main ON/OFF switch is set OFF, the AC supply will come tto above said two components. If a lighning or sudden line over voltage occur, it will effect these two components, if main control switch at the wall power outlet is not switched OFF.
Desolder out [NT 802S - 4.7Ohms] thermistor from circuit. this will isolate the switching section STR and all other components. Check all the four rectifer diodes [D803S, D802S, D804S&D801S] for short. measure the reverse resistance to these diodes by an ohm meter. If found leaky, replace them. It is best to replace them all at one time. Check [C808 - 1000PF 400V] too. A leaky capacitor will also be the cause or blown up fuse. If all of the above components are OK, desolder one end of [L802], which in turn supply voltage to drain lead of the power switching controlled MOSFET. Now measure the resistance between pin number 1 [Drain] and pin number 2 [Source] of the internal MOSFET of the switching regulator. the resistance to these two terminlas must be very high. If found low or measures apporximately equal to zero Ohms, the power switching regulator IC [IC 801C], is faulty. It should be replaced with same number.
But, before replacing this component, chak all the other components connected to this switching device. Desoler out the swithcing IC from circuit and check each component. Check zener diodes DZ 803- 27V & DZ 805- 18V] for any damage. It is best to replace these two zener diodes.
There are nothing more to chek in special, as the power swithichg regulator section of this model is much simple to troubleshoot related to other color TVs power supply section.
If main rectifer diodes [four of them said above] found shorted, it will be best to replace C801 - 220MFD 400V] (Main filter cpacitor), and [PC 801S - PC 123Y], the optocoupler, even they measures OK.
The two output voltages from this power supply section are 112VDC; at cathode of [D805 - RU2GA] and 16.6VDC at the cathode of [D807 - RU20A].