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You have to check the pin control transistor in the horizontal section. It will be fitted on the same heatsik on which the horizontal output transistor is fitted.It will be a small transistor as compaired to the horizontal driver. Also you have to check the three mosfets in this section used to control the width.
If there is no display but only the monitor seems to switch on , hearing noise, then there could be a possible failure of the line output transformer. You will need to check out by opening the rear cover after disconnecting the power. power on the monitor for some time maybe about 10 minutes and switch off. Try to touch the LOT or the driver output transistor for heating, If so you have a failure of either or both of these components. If not you will have to check out the +B , main power line to the circuit for a break in the fusible resistors or the diodes in the power supply smps unit. Check also to see if there is any dry or loose connections in the CRT base unit. If so solder and check also on the main board for dry joints. Helpful I hope. Good day
your irf 630 is not original purchase it from proper LG authorised service centre it is costly but never become faulty again duplicate mosfet overheats if your green led is on then measure voltage at E.H.T.connect meter at output transister if E.H.T. is producing then meter should show 1 digit if not then 50v will show take care that signal cable should be disconnected if E.H.T. is not producing then check +vcc at horizontal ic it should be 12v. if 12v is not present then check regulator ic 7812 insmps
Through my past experience I mwould remove the solder point at the input power B+ line to primary winding FBT. If the HOT has shorted there will be no power.Straight to the point if you know where the HOT is , you can desolder the middle pin or collector of the HOT transistor. If you desolder the pin which result the power led light turn up. That indicates either FBT or HOT has shorted
Check components related with pots thats adding command ic to pots.If they are ok then change command ic with new one.Before this you can check horizantal hold transistor that is placed on hitsink of eht.small in size and check two small transistor placed near it on pcb.Hope this solution works .If not then i am here