LED lights that get worse the more they are repaired

se7ens

LED lights that get worse the more they are repaired [Copy link]

The LED light at home is broken. Refer to the suggestions of previous netizens and you can replace it.

So I took it apart and looked at

18W LED light

After disassembling the PCB, I found a bad pixel

It should be a constant current drive solution

I checked this chip TC6921L, a domestic LED constant current driver chip

Short-circuit the bad point

Power on and test it, it works

However, after using it for a few days, the light flickered a few times after I turned it on one day, and then it broke again.

I wanted to see what the problem was, so I took it apart and took a look.

This time the lamp is broken more

After short-circuiting, the brightness seems to be reduced by half. Is it the end of the LED? I don’t know when all the LEDs will fail.

I changed it again with trepidation, not knowing how long it would last, so I bought a similar LED light online as a backup.

I feel that LED lamps are not as durable as previous incandescent lamps.

dcexpert

LEDs now have high brightness, but they age quickly, and their brightness usually drops significantly after half a year.

qwqwqw2088

The light flashed a few times after I turned it on, then it went out again.

There is a problem with the driver power output, and the output voltage ripple is too high

The output constant current is large.

se7ens

qwqwqw2088 posted on 2022-4-30 12:00 After turning on the light, it flashed a few times, and then it broke again. There is a problem with the output of the driver power supply. The output voltage ripple is too high and the output constant current is large. This will also happen...

It's possible. I measured the capacitance and it's OK, it's attenuated a little bit.

tagetage

LEDs die from overwork, how can we sell new ones when they are old and never break? The rated current of 100mA must pass 200mA.

se7ens

tagetage posted on 2022-4-30 12:48 LEDs die from overwork. How can we sell new ones when they are old and not broken? The rated current of 100mA must pass 200mA.

This is a constant current drive. How come the current is doubled?

tobot

Haha, I broke one recently too, so I'll try to fix it myself?

tagetage

se7ens posted on 2022-4-30 17:23 This is a constant current drive, how come the current is doubled

I mean the rated current of the LED is 100, and the constant current output is 200.

不亦心

It is not easy for such a simple driver to be used for so many years. The whole board cost a little more than 1 yuan, and the input and output capacitors are probably at the end of their life.

LZ can try to replace the high-temperature capacitor with a larger capacity and increase the CS resistance.

jqbf1998

This problem can be solved by increasing the current limiting resistor and reducing the current.

se7ens

Bu Yixin posted on 2022-5-2 19:54 It is not easy for such a simple driver to be used for so many years. The whole board was bought for a little more than 1 yuan, and the input and output capacitors are probably at the end of their life...

Makes sense, you can try it