Panasonic M12H power supply - power circuit - circuit diagram - Huaqiang Electronic Network

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The color TVs using the Panasonic M12H movement are: Panasonic TC-230H, TC-2030DHN, TC-830D, TC-840D, etc.

Oscillation process

Approximately 300V DC voltage on C836, one pass through the P801 and P2 windings of T801 is added to the C pole of the internal switch of IC1 (1), and is added to the B pole of the internal switch of (2) of IC801 via R803. The tube starts to conduct, and the E pole current flows from the (4) foot of the IC801. The current of P1 and P1 windings of T801 increases, and the induced voltage is generated, which is coupled to the windings of F2 and F3. At this time, the induced voltage polarity of F2 and F3 windings is F2 positive F3 negative, and this voltage is added to IC801 through C806 and R804 (2). ), (4) feet, so that the switching tube current is further increased, and strong positive feedback causes the switching tube to quickly saturate.

After the switch tube is saturated, the voltage of the primary winding of T801 increases linearly. On the one hand, 113V DC voltage is formed at the (4) pin of IC801, and T801 stores the magnetic field energy. As the C806 is continuously charged, the voltage at the IC801(2) pin is continuously lowered, and finally the internal switch is pulled out of saturation.

Once the switch tube is out of saturation, the current of P1 and P2 windings of T801 will decrease, the polarity of the induced voltage of each winding of T801 will be reversed, and the voltage of F2 and F3 windings will be sent to IC801 by C806 and R804 (2), (4) The foot makes the current of the switch tube further reduced, and the cycle makes the switch tube cut off quickly.

After the switch is turned off, the voltage of T801 S1 and S2 windings turns D801 on, and 16V voltage is established on C810; F1 and F3 windings make D804 also turn on, the magnetic field energy stored in T801 is released to 113V load through D804, and C806 The F2 and F3 windings of R804, D806 and T801 are discharged, and the 300V voltage is reversely charged to C806 via R803, so that the voltage of (2) of IC801 is raised, and the reverse pulse is also sent to the (2) foot of IC801 via D805 and R805. The IC801 is turned on in advance to start another oscillation cycle.

Regulator circuit

The voltage regulator circuit is automatically completed internally by the STR456A.

protect the circuit

If the voltage of 113V rises, D837 is turned on after R842 and R843 are divided, the thyristor Q833 is turned on, 220V AC is short-circuited, and the fuse is burnt.