Philips 10.5w 800 lumen premature failure
- Thread starter PhotonWrangler
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PhotonWrangler
Flashaholic
The narrow end of the pcb extends all the way into the screw base at the bottom of the bulb, so the capacitor is probably benefitting from some heat sinking from the socket itself.
**Edit**
A second one just failed. No flickering or sputtering - it just suddenly went dark. One failure is a fluke but two is a pattern.
** Another Edit **
Took the bad bulb out of the bathroom fixture and replaced it with a new identical one. It's working fine. Then I took the "bad" one and put it into my desk lamp tonight and it's working again.
**Edit**
Tonight I measured the temp at the base of one of the bulbs in this fixture and I got 183 degrees F at it's hottest point, right where the metal screw base meets the white sidewall of the lamp. This lamp is running base-up in an open glass fixture.
**Yet another edit**
Measured the same model of bulbs in an open fixture with the bulbs mounted horizontally. The temperature at the hottest part of the base was 155 degrees F.
**Edit**
A second one just failed. No flickering or sputtering - it just suddenly went dark. One failure is a fluke but two is a pattern.
** Another Edit **
Took the bad bulb out of the bathroom fixture and replaced it with a new identical one. It's working fine. Then I took the "bad" one and put it into my desk lamp tonight and it's working again.
**Edit**
Tonight I measured the temp at the base of one of the bulbs in this fixture and I got 183 degrees F at it's hottest point, right where the metal screw base meets the white sidewall of the lamp. This lamp is running base-up in an open glass fixture.
**Yet another edit**
Measured the same model of bulbs in an open fixture with the bulbs mounted horizontally. The temperature at the hottest part of the base was 155 degrees F.
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PhotonWrangler
Flashaholic
Hi Snakebite,
I looked at the LED plate and the individual leads are covered up by the white solder mask. I might rig an external power supply around 100 volts and place it across the string and see if it lights up.
I looked at the LED plate and the individual leads are covered up by the white solder mask. I might rig an external power supply around 100 volts and place it across the string and see if it lights up.
LEDninja
Flashlight Enthusiast
CPF first came across these bulbs only a year ago.
http://www.candlepowerforums.com/vb...ips-bulbs-800lm-amp-450lm-bulbs-at-Home-Depot
To have 2 failures since that time is bad news. They are my favorite bulbs too.
Do you have an estimate of how many hours they have been running before the failures?
What kind of fixtures and the ambient temperature?
The heat issue led me to get the 6W Cree instead of the 9.5W. Posts 244 to 246.
http://www.candlepowerforums.com/vb...0K-for-13-97&p=4213642&viewfull=1#post4213642
But my HD do not have the 450 lumen version of the Philips.
http://www.candlepowerforums.com/vb...ips-bulbs-800lm-amp-450lm-bulbs-at-Home-Depot
To have 2 failures since that time is bad news. They are my favorite bulbs too.
Do you have an estimate of how many hours they have been running before the failures?
What kind of fixtures and the ambient temperature?
The heat issue led me to get the 6W Cree instead of the 9.5W. Posts 244 to 246.
http://www.candlepowerforums.com/vb...0K-for-13-97&p=4213642&viewfull=1#post4213642
But my HD do not have the 450 lumen version of the Philips.
PhotonWrangler
Flashaholic
The first failure was after maybe 40-50 hours of runtime. Temperature readings on a working bulb -
Base of the bulb measured 183 degrees F at it's hottest point, right where the metal screw base meets the white sidewall of the lamp. This lamp is running base-up in an open glass fixture. I measured the same model of bulb in an open fixture with the bulbs mounted horizontally. The temperature at the hottest part of the base was 155 degrees F.
I have a third bulb that has started to flicker occasionally. It's only done it twice that I noticed, but it was the same type of flicker that preceeded the failure of the first bulb.
Base of the bulb measured 183 degrees F at it's hottest point, right where the metal screw base meets the white sidewall of the lamp. This lamp is running base-up in an open glass fixture. I measured the same model of bulb in an open fixture with the bulbs mounted horizontally. The temperature at the hottest part of the base was 155 degrees F.
I have a third bulb that has started to flicker occasionally. It's only done it twice that I noticed, but it was the same type of flicker that preceeded the failure of the first bulb.
PhotonWrangler
Flashaholic
Just had another one of these bulbs fail. This makes failure #4 for about a 40% failure rate so far. This was running in an open fixture in the kitchen. There is definitely a Q/C issue going on here. No more of these bulbs for me. 
Just had another one of these bulbs fail. This makes failure #4 for about a 40% failure rate so far. This was running in an open fixture in the kitchen. There is definitely a Q/C issue going on here. No more of these bulbs for me.
Yes, a QC issue to be sure. I've had 1 of 20 LED bulbs fail. It was the $10 Utilitech from over two years ago. It quit the day after I bought it. I remember in the 90's when electronic ballasted CFLs were starting out. It took them a few years to get a good electronic ballast figured out.
Cree came out with a cheap bulb, so Philips came out with something even cheaper. You get what you pay for... these things are crap.
Steve K
Flashlight Enthusiast
Do we have enough data to know if the problem is excessive heat, poor manufacturing process (poor soldering, ....), lousy materials (cracks in circuit board traces), ....??
PhotonWrangler's report of seeing 183F on the hottest part of the lamp (externally). That's 84C, which shouldn't be lethal, but the junction temperature of the LEDs is going to be hotter. Doesn't seem good, but also doesn't seem like it should kill the lamp. It should just cause the LEDs to dim prematurely, right?
PhotonWrangler
Flashaholic
I'm going to disassemble the latest bad one and see if it's the power supply or the LED string that failed. When I took the previous one apart I didn't see any signs of poor assembly techniques. The solder joints and PCB traces looked ok and there were no obvious signs of heat damage so I'm not sure what the culprit is yet.
**Update**
It was the driver that failed. I'm getting about half a volt out of it.
I also discovered an easier way to remove the dome. Place the dome portion of the lamp in a vise and clamp down carefully until it deforms the dome enough to crack the glue seal, then it's easy to pry it off.
**Update**
It was the driver that failed. I'm getting about half a volt out of it.
I also discovered an easier way to remove the dome. Place the dome portion of the lamp in a vise and clamp down carefully until it deforms the dome enough to crack the glue seal, then it's easy to pry it off.
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Derek Dean
Flashlight Enthusiast
What concerns me is the sheer number of separate electronic components, and solder joints, contained in that light, increasing many times the chance for a failure. Still, I just bought 4 Cree LED bulbs at Home Depot and hopefully won't have to use their 10 year warranty.
Steve K
Flashlight Enthusiast
bad electrolytic, maybe??
I don't know if it helps, but I had a CFL that had a transistor get so hot that the solder reflowed, allowing the transistor to just fall out of the board. Weird, but kinda cool.
PhotonWrangler
Flashaholic
bad electrolytic, maybe??
I don't know if it helps, but I had a CFL that had a transistor get so hot that the solder reflowed, allowing the transistor to just fall out of the board. Weird, but kinda cool.
Wow.
I used to have an old G-E tube color tv. They ran the horizontal output tube so hot that the glass actually softened and the tube envelope deformed slightly.
oo:Realistically its not many components but failure rate is compounded by heat. Most electronics items have way more parts.
Semiman
Sent from my Nexus 4 using Tapatalk 4 Beta
PhotonWrangler
Flashaholic
I decided to start removing components from the first dead bulb and try to find out what failed. I desoldered all of the active components as well as some of the passive ones and this is what I've found -
(1) 47uf 160v electrolytic capacitor - measured exactly 47uf - tested ok
(2) MJE13003 NPN HV transistors - tested ok
(1) BT169DH SCR - tested ok
(4) GU1M 1000v switching rectifiers - tested ok
I also measured the other surface mount diodes on the board and they all tested ok, and I got continuity on the transformer.
I removed a small coil from the board (added pictures in my photostream) and it measured open circuit. So I carefully removed the black rubber jacket and found that one wire was broken off at the base. This might have happened when I was pulling the potting compound off the board.
I haven't measured the SM resistors on the board yet and that's going to be difficult. So I still don't know for sure what failed. :thinking:
**More**
I measured the surface mounted resistors today and while some of them were dead on, others measured anywhere from 20-30% lower than their marked value. Not sure if this is contributing to failures but it makes me wonder about the quality of the resistors.
(1) 47uf 160v electrolytic capacitor - measured exactly 47uf - tested ok
(2) MJE13003 NPN HV transistors - tested ok
(1) BT169DH SCR - tested ok
(4) GU1M 1000v switching rectifiers - tested ok
I also measured the other surface mount diodes on the board and they all tested ok, and I got continuity on the transformer.
I removed a small coil from the board (added pictures in my photostream) and it measured open circuit. So I carefully removed the black rubber jacket and found that one wire was broken off at the base. This might have happened when I was pulling the potting compound off the board.
I haven't measured the SM resistors on the board yet and that's going to be difficult. So I still don't know for sure what failed. :thinking:
**More**
I measured the surface mounted resistors today and while some of them were dead on, others measured anywhere from 20-30% lower than their marked value. Not sure if this is contributing to failures but it makes me wonder about the quality of the resistors.
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if several leds hadnt got damaged you could put it back together and try it.
remember that no matter how good a design you have all it takes is for one parts supplier to have a bad run on a part for you to have a bad run of product.
and 185 f at the base?
that cheap lytic wont last long!
and as was mentioned earlier the tj of the leds is going to be through the roof!
FAIL!
remember that no matter how good a design you have all it takes is for one parts supplier to have a bad run on a part for you to have a bad run of product.
and 185 f at the base?
that cheap lytic wont last long!
and as was mentioned earlier the tj of the leds is going to be through the roof!
FAIL!
Samxon are tolerable quality for caps. 185 is high but odds are Tj will not be much higher given number of leds. Without knowing if the cap is oversized can't judge its in app life.
Hard to measure resistors if not isolated from other parts so unless you remove them from the board could easily be way off.
It could be the controller IC that failed. Need to scope the board to figure that out.
Sent from my Nexus 4 using Tapatalk 4 Beta
Hard to measure resistors if not isolated from other parts so unless you remove them from the board could easily be way off.
It could be the controller IC that failed. Need to scope the board to figure that out.
Sent from my Nexus 4 using Tapatalk 4 Beta
PhotonWrangler
Flashaholic
Yeah, I thought about that. It is possible that I'm reading some shunt current paths around other components. Most of the through-hole stuff has been removed so that effect should be minimal but I can't rule it out.
I still have another dead one that I have yet to tear down. Now that I know how it's put together, I should be able to do a better job of disassembly next time which might reveal the problem components.
