Repair of the power supply unit of the TV Funai

[shapanwwuom]

Hello everyone. Today I will tell you about repairing the power supply unit of the Funai TV-A2000A TV . According to the owner, the TV became unusable after a power surge. He had already repaired it several times by replacing the fuse, but this time this procedure did not help.

The TV is assembled on the MK8 chassis . After removing the back cover, I saw the same "fuse" that the owner changed.

Jumper instead of fuse

The only thing that saved me from blown fuses on the meter was that the TV is turned on via a relay, not via a button.

First, I removed the "fuse" and soldered a 100-watt lamp in its place . This will prevent a short circuit in the event of some kind of imperfection in the circuit.

Incandescent lamp instead of a fuse.

The first to be tested was the diode bridge. All the diodes australia telegram data showed a short circuit, and in order to make the measurements more accurate, I unsoldered one leg from each diode.

As a result, only 2 diodes turned out to be faulty.
Burnt out diodes.

Next, I checked the 1.2 Ohm 5 Watt resistor . It turned out to be open.

These resistors are installed to smooth out the initial voltage surge at the moment of switching on.

I didn't have such a resistor on hand, so I decided to solder a 2.2 ohm 5 watt resistor in a different case instead.

Having soldered the pins onto this resistor, I installed it on the board.

After that, I moved on to measuring the short circuit on the network capacitor C607. The measurement showed zero resistance.

short circuit on capacitor c607

Since capacitors themselves rarely short-circuit, I unsoldered the power transistor of the power supply. It turned out to be the C3752 transistor , which was completely short-circuited.