Question about Philips TP3281C TV

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Philips tp3281c chasis#32d700-7570

How can I test the horizontal output transistor of this set with a simple multimeter?

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  • pamminger Aug 30, 2007

    The H.O.T has 3 pins. I assume that from left to right, the first pin is (B)the base. The middle pin is (C)the collector, and the last pin on the right is (E) the emitter. I first tested the H.O.T. using the analog MM in a 10 ohm setting. There can only be 6 combinations with the test readings as follows where continuity = 0 or some measurable ohms of resistance; no continuity = infinite resistance:
    Red lead of mm to B, Black lead of mm to C; the reading is no continuity
    Black lead of mm to B, Red lead of mm to C; the reading is + continuity
    Red lead of mm to B, Black lead of mm to E; the reading is +continuity
    Black lead of mm to B, Red lead of mm to E; the reading is +continuity
    Red lead of mm to C, Black lead of mm to E; the reading is + continuity
    Black lead of mm to C, Red lead of mm to E; the reading is no continuity
    Next the six various combinations were then tested with a digital MM set into the diode testing mode where non-touching leads display a reading of 1 and when the leads are touching the device reads 0:
    Red lead of dmm to B, Black lead of dmm to C; the reading is .426
    Black lead of dmm to B, Red lead of dmm to C; the reading is 1
    Red lead of dmm to B, Black lead of dmm to E; the reading is 0
    Black lead of dmm to B, Red lead of dmm to E; the reading is 0
    Red lead of dmm to C, Black lead of dmm to E; the reading is 1
    Black lead of dmm to C, Red lead of dmm to E; the reading is .426

    I am not sure exactly what these results represent! Based on the above test results, is the H.O.T. is good or bad? Would appreciate any feed back.

    Thanks, peter



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I believe this set has a horizontal output that has a damper diode inside. you can check inset or out, most popular is out set. take multimeter and put on ohms or continuity and touch each leg by holding one lead to end and if you are looking for a short then in continuity it will beep or zero or very ohms. And Ohms just the same way. looking for low ohms like 1.0 or 0.9 or anything close. Switching leggs back and forth. If all three legs are shorted then replace. but in this one 2 can be shorted and still be good, just depends on which ones

Posted on Aug 29, 2007


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If the secondary supply rail 125VDC is found ok, just goto to the Horizontal Output Transformer, a small transformer diretly soldered on tho the main board, very near to the Line Output Transformer [LOT], and its secondary winding is connected to the base of the line output transistor, which in turn drives the LOT said above, generates EHT you described.
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