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Fire emergency lights can solve the problem of temporary power failure, so many households in urban and rural areas have emergency lights to use in case of power failure.

Of course, due to various reasons, emergency lights in use will inevitably break down.

This paper analyzes the common faults and maintenance methods of an 11W national emergency lamp for reference.

When the power supply is normal, the 220V AC voltage is reduced by T1, rectified by VD1~VD4 and filtered by C1, and about 14V DC voltage is obtained. The 12V battery is charged by isolating diode VD6.

At the same time, the indicator light VD5 is on, indicating that the municipal power supply is normal.

After the blackout, the indicator light VD5 goes out.

If lighting is not needed during the day, SA1 need not be closed. The oscillating circuit will not work and the emergency light will not turn on.

At night, when lighting is needed, SA1 can be closed, the oscillation circuit can be activated, and the emergency light is lit.

Ii. Failure Maintenance [2]

1. The emergency light is not on after switching on the switch SA1

Disconnect SA1 and use dc 1A of the multimeter (if there is no such gear, it can also be measured at 500mA gear speed) at both ends of SA1. The current should be around 500-V 600mA in normal time.

Note that the switch SA2 should be in the "ignite" position.

If the current is normal, SA1 damage, need to replace: if there is no current, should focus on checking the winding Of T2 L4, L5, the use of a multimeter ohm measurement judgment: finally under the VT test its performance is good, to replace the available value of more than 120 in the middle power tube.

If there is still no current, then use the multimeter to check whether resistance R2 and R3 are variable or open, and whether VD7.C2 is short.

After the above maintenance treatment, switch ON SA1, the lamp tube should be able to light up normally.

Details can also see: fire emergency lights function and related common sense!

2. The power supply is normal but the indicator light is not on

This fault is mostly caused by led damage. VD5 can be welded with a multimeter to determine whether it is intact or not.

VD5 will not be bright if the resistance value of current limiting resistor R1 is increased or is open.

The indicator light is still on when the power goes out

The fault is due to VD6 reverse characteristic variation or breakdown.

Simply replace an IN4004 rectifier diode and the fault will be removed.

4. After the power failure, the lamp tube works normally for a while and then the brightness drops

This indicates a possible malfunction in the battery.

Because the circuit does not prevent the battery overdischarge protection measures, if the power outage time is too long, the battery overdischarge to the end voltage 10V, failed to disconnect SA1, will make the battery overdischarge and lead to premature damage of the battery plate.

The best way to solve the battery overdischarge is to set up the protection circuit,

5. Lamp tube ignition circuit fault

The role of the emergency lights in the circuit switch SA2 is: when closed SA1 SA2 on the "start" position, T2 oscillation transformer winding voltage by SA2 on L1 and the power (battery) added to the tube filament, and winding the voltage on the L3 on tubes at the other end of the filament, after about three seconds of preheating, switch SA2 dial to "fire" position, at this point, the winding L2 on induction of high frequency pulse voltage on both ends of tubes, lamp lit up.

According to the above working principle, when troubleshooting lamp tube ignition, first check whether the switch SA2 is in good contact, and then check whether the filament of the lamp tube is in good condition. The resistance value can be measured by the multimeter RX1.

As the filament of the emergency lamp is preheated and the voltage waveform is improved by capacitor C3, the phenomenon of blackening at one end of the lamp is generally less.