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AKAI CT-2107D (common power supply failure)
This frequent malfunction concerns not only this TV, but all televisions. Most often, electrolytic capacitors dry out, which is why some TV sets start with difficulty at first, then they stop switching on completely. In others, as in AKAI CT-2107D, when the con- dens dry up, the power supply unit gives an increased voltage to the entire TV set. Therefore, for any repairs, it is desirable to check the capacitors in the power supply and, if necessary, replace them. In this case, the electrolytic capacitors C911 and C909 are 47μF 50 volts.
With increased voltage on the drain sweep, the secondary power supply from the TDX also produces overstated voltages. As a result, in this model the zener diode ZD401 (at 12 volts) breaks down - short-circuiting the case. In the rectifier circuit there are two resistors R421 (0,68 Ohm) and R419 (3,3 Ohm), some of which necessarily will burn. The TV will not work, but the power supply will give an increased voltage to the whole TV and can burn much.
Instead of the zener diode ZD401, you can not put KREEN 7812, as in the event of a power failure, it will not fail, and other details-horizontal line filter filter capacitors, horizontal output transistor, TDX and other details.
In general, because of the increased voltage on the line scan - there is increased radiation of the kinescope, which, as you know, leads to a deterioration in health. Thus, the failure of the Zener diode ZD401 speaks first of all of the failure of the power supply. And if there is a Krenka 7812,
then, apart from the burnt parts, the customer also receives radiation from the kinescope.
Such a scheme of the TV, but it can be improved by placing a protective avalanche diode R2K or R2M on the chain of 115 volts - supply of urgent sweep.
With such a defect, if it does not, the chip of the frame scan LA7830, which is powered by a voltage of 25 volts from the TDX, is out of order. In general, we can say that with such a malfunction, it almost always flies.
Well, if very unlucky, then the processor on the AN5601K chip may fail.