Over current protection circuit detects an overload on B+135VDC, supply line to LOT and Horizontal oscillator drive section, and gives the indication by two continuous blinks.
Desolder and disconnect one end of resistor R502 (1.2 Ohms 2W), which supplies the voltage to LOT. Connect a 100W 220VAC filament type bulb, to B+ and ground, using two pieces of wire and a bulb holder. Switch ON the set. Measure the B+voltage with respect to negative. Should show around 134 to 137VDC. If the voltage measured seem to be over than this range, check the power supply switching regulator section. Check all the solder terminals at the power switching section, and make sure that this voltage does not exceed the limit stated above.
If 135VDC is right, with a 100W bulb load, and set shows the over voltage indication when connected to LOT, the horizontal output section should be checked well for any short circuit. Desolder out the horizontal output transistor (2SD-2624 CA) (Q801) from the circuit board. Now switch the set ON and see the indication is there. If not, make sure that the horizontal output transistor is leaky. There may some reason for the failure to this transistor. The first one is with shorted windings inside the LOT itself. The second one is with loose fixation of this transistor with its heat sink, makes it overheat and get shorted. The third one is, shorted windings at the horizontal side of the deflection yoke.
Anyway, we have to fix an other good transistor of same type and number in place to do further check. Replace the transistor; fix it well with its metal heat sink. Switch ON the set for a short period of time, say 3 or four seconds. Unplug the Ac chord from wall socket, and feel the heat of the replaced transistor by bare figure touch. It may get slight warm, but not too overheat. If it overheats at this short period of time, make sure that the LOY (NX-4751-M3A4) is defective. Replace the LOT with same number. Never try to substitute any other number LOT to this set, as it may lead bad results.
If the trouble was with horizontal output transistor only, you will get the raster within 5 seconds after you switch the set ON.
The deflection yoke complaint is very rare, say 1 out of 1000. If the deflection yoke has shorted windings inside it, the set will make hissing sound, and the horizontal output transistor we substitute will get shorted as soon as we switch ON the set. We won’t get any time to detect it.
