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LED bulb dimmed

starLED

Member
When I switched on the lights today in my kitchen, I have noticed that one LED bulb E27 is dimmed.
At first I thought it was a bad bulb, but when I replaced it with a new one, same thing happened, it was dimmed again.
I checked E27 socket voltage, and it was 220 V (standard in Serbia).
When I switch on the lights, bulb is slowly lighting up.
What can be a problem?
Is the socket problem?
Also, I noticed a switch doesn't click as it did before, I can feel its a bit soft.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
When I switched on the lights today in my kitchen, I have noticed that one LED bulb E27 is dimmed.
At first I thought it was a bad bulb, but when I replaced it with a new one, same thing happened, it was dimmed again.
I checked E27 socket voltage, and it was 220 V (standard in Serbia).
When I switch on the lights, bulb is slowly lighting up.
What can be a problem?
Is the socket problem?
Also, I noticed a switch doesn't click as it did before, I can feel its a bit soft.
It sounds like perhaps the switch isn't working properly, I suggest you check that - easy way, turn the power off, and join the wires together at the switch.
 

starLED

Member
I removed the switch and mesaured voltage in live wire.
Strangely, showed me 105 V,
I joined wires together and measured at socket, and it showed 230 V.
Then I mesaured again in live wire, and it showed 135 V.
Can the socket be an issue?
Neutral wire was a bit stuck in a switch, there's a button to press to release it, and it didn't work (had to cut the wire), maybe switch was bad.
On the same line there is fridge also, maybe fridge is using 110 V.
Also if wires are not connected, there is still a voltage in socket around 020 V.
 
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
When you shorted the switch out did the bulb work at full brightness?, also you don't mention where you measured the voltages from - also the tiny load presented by a meter makes voltage readings fairly pointless, unless there's enough load to make the readings accurate.
 

starLED

Member
When you shorted the switch out did the bulb work at full brightness?,
Yes.

also you don't mention where you measured the voltages from - also the tiny load presented by a meter makes voltage readings fairly pointless, unless there's enough load to make the readings accurate.

Voltage in wires at the switch = 135 V. Its constant, no fluctuations.

I tested voltages with different fuses on/off.
When only fuse for socket is on, there is 105 V in wires at the switch.

When other fuses are on there is 135 V.
 

Dr_Doggy

Well-Known Member
if the socket is not connected to anything at all, it shows 20v?

As mentioned, there is concern that you are taking readings correctly, a diagram of where you are testing may be ideal (pls include where you hook up ground lead)
 

starLED

Member
I have solved the issue, but the hard way! :banghead:

First, I replaced the light switch, that didn't solved the dimmed bulb issue.
Next, I have tested bulb socket with a bulb and while testing I have accidently caused short circuit (connected live and neutral with bulb screw) and I have blown the fuse 20A. :arghh:
I have replaced fuse 20A and I have determined that bulb socket connections are a bit damaged (corroded) and loose.
I have replaced bulb socket and now everything is working fine.
if the socket is not connected to anything at all, it shows 20v?

As mentioned, there is concern that you are taking readings correctly, a diagram of where you are testing may be ideal (pls include where you hook up ground lead)
Yes, while switch is off (opened) it's showing 20V.
I am not sure how it's wired, but it seems that it's connected to something else.
On the light switch there are 135 V, but in the bulb socket there are 220 V.
 
Last edited:

rjenkinsgb

Well-Known Member
Most Helpful Member
It's not at all unusual to get quite high voltage readings on open circuit or disconnected cores of power cables, due to capacitive coupling from live cables nearby.

As a typical digital multimeter is around ten megohms input resistance, it does not particularly "load down" that stray voltage like as a lamp or other direct connection would.
 

gary350

Well-Known Member
If 1 in a group of several bulbs acts weird check see if all the bulbs are identical. I had a 4 bulb light fixture do that 1 bulb was made by a different manufacture. I also notice when turning off the light all 4 bulbs slowly get dimmer until light is off it takes slight longer than 1 second for all 4 bulbs to go off like a capacitor is discharging.
 

starLED

Member
Yes, I know, but here wasn't the case of a bad LED bulb, it was a bad wall switch.
In case of a burned diode, you can also just remove it and connect traces on PCB, but the bulb will be less bright.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Yes, I know, but here wasn't the case of a bad LED bulb, it was a bad wall switch.
Pretty unusual I would have thought, particularly with the low power requirements of LED bulbs - well done finding it.

Where I worked we were a major Grundig dealer for many years, and I used to get repairs brought in from all over the country at times. One particular fault on a CRT TV chassis was a frame fault, the height was too low, and if you tried to turn it up the top of the picture folded over.

The first one I came across took me ages - and I eventually found that the fuse feeding the frame output was slightly high resistance - it was quite rare to even have a fuse feeding the frame output, and high resistance fuses were totally unknown.

I can only imagine the fuses were from the same batch, and had a manufacturing defect - but after the first one I saw lot's more, and then sets started appearing from all over the country :D When you took the back off they all had had the frame IC replaced, the capacitors, pretty well everything replaced - just pop a new fuse in, job sorted :D
 

starLED

Member
I can only imagine the fuses were from the same batch, and had a manufacturing defect - but after the first one I saw lot's more, and then sets started appearing from all over the country :D When you took the back off they all had had the frame IC replaced, the capacitors, pretty well everything replaced - just pop a new fuse in, job sorted :D
Knowledge is power.
It must've been quite a physical workout working on those CRT's, compared to lighter LCD TV's.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Knowledge is power.
It must've been quite a physical workout working on those CRT's, compared to lighter LCD TV's.

36 inch Sony's were probably the heaviest (Trinitron CRT's weigh more than others - thicker glass), you could barely lift them with two people, and on the box it recommended four people - but there's no way to get through a doorway with four people round it.
 

starLED

Member
Those 36 Sony's weighted 98 kg. My piano weighs less. ;)

h15836FV16_MT.jpeg
 

Nigel Goodwin

Super Moderator
Most Helpful Member
Those 36 Sony's weighted 98 kg. My piano weighs less. ;)
Acoustic or Electronic :D

I bought my daughter one, had to be electronic as it had to go upstairs - pity as I was offered a number of acoustic pianos for free. Even the Yamaha electronic one was pretty heavy to take upstairs though, basically a big heavy keyboard and flat pack piano shaped case, pedals etc.
 

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