Problem with my Nitecore EA4 (SOLVED)

maxhawk · Jan 3, 2016

My 20-month old Nitecore EA4 failed last night and I'm reaching out to see if anyone else has run across this issue.

The light behaves as if it's detected a low voltage condition -- it comes on, but only at one level that's probably no more than a lumen or so. I get the same behavior whether I do a hard press of the switch for high, or soft press to get to the lower brightness modes. It was working fine in high mode when I got an intermittent blink a couple of times. After the third time I thought maybe the batteries had died since it shut off. I swapped in some fresh batteries and found that it only operated in the aforementioned manner.

I've confirmed that the voltage on the batteries are ok (~1.37V on each AA). The light was not hot while in use since I operate this light only for 60 seconds max at a time on high with a diffuser to use a lint roller on my bed to get the cat hair off. I see no damage to the contacts on the rear cap. Sharp hits with my hand doesn't make the light work normally, so probably no intermittent connections in the circuit.

I'm an EE so I don't mind taking it apart but I no longer have access to test equipment, so troubleshooting will have to be limited to looking for components with apparent damage or poking around with a DVM. How does one access the circuit inside? It looks like the silver ring on the bezel may unscrew, but I didn't want to attack it with slip ring pliers until I know it's supposed to come off.

Thanks for any suggestions.

swan · Jan 3, 2016

Re: Problem with my Nitecore EA4

To access the driver-

Remove bezel ring by placing hard down on a mouse pad [or similar] and twist - no damage this way,

Take out lense, oring reflector and white reflector seat and remove tailcap,

Now this is the tricky part, you have to push the driver out from the battery side as it is press fitted. The internals are- led and star on a alumiunium heat sink, driver, battery pcb, polarity washer and poly cage. The switch cover stays in place .

To avoid damage, what i did was make a simple tool from a piece of poly water pipe approx 60mm long, 10mm-12mm wide, which you centre over the positive terminal so it touches the board not the terminal, which we use to push out the driver.

To do this [ if you do not have a press handy] place light back down on mouse pad and place a rag in over led so it dosent damage the led/driver assembly when it drops, place poly pipe over left + terminal and very softly tap down once, then the right, slowly alternating being careful . It only has to move a couple of mm,s and the whole assembly will drop softly onto your rag.

I have pulled mine apart a couple of times and now has a new rubber switch boot and a xml2 u3 on a copper pcb- good luck with your issue.

maxhawk · Jan 4, 2016

Re: Problem with my Nitecore EA4

Awesome, your instructions worked perfectly! I used a 10mm nut driver and its head fit perfectly in the space. It looks like the LED needs to be desoldered to separate the pieces, so that will have to wait until tomorrow or later this week.

swan · Jan 4, 2016

Re: Problem with my Nitecore EA4

maxhawk said:
Awesome, your instructions worked perfectly! I used a 10mm nut driver and its head fit perfectly in the space. It looks like the LED needs to be desoldered to separate the pieces, so that will have to wait until tomorrow or later this week.

Excellent, yes the led will need to be desoldered as the wires run through the heatsink, but before you do, try and hook voltage straight to the driver and operate, to rule out the tailcap circuit. Will be interesting to get your findings.

Overclocker · Jan 4, 2016

Re: Problem with my Nitecore EA4

maxhawk said:
My 20-month old Nitecore EA4 failed last night and I'm reaching out to see if anyone else has run across this issue.

The light behaves as if it's detected a low voltage condition -- it comes on, but only at one level that's probably no more than a lumen or so. I get the same behavior whether I do a hard press of the switch for high, or soft press to get to the lower brightness modes. It was working fine in high mode when I got an intermittent blink a couple of times. After the third time I thought maybe the batteries had died since it shut off. I swapped in some fresh batteries and found that it only operated in the aforementioned manner.

I've confirmed that the voltage on the batteries are ok (~1.37V on each AA). The light was not hot while in use since I operate this light only for 60 seconds max at a time on high with a diffuser to use a lint roller on my bed to get the cat hair off. I see no damage to the contacts on the rear cap. Sharp hits with my hand doesn't make the light work normally, so probably no intermittent connections in the circuit.

I'm an EE so I don't mind taking it apart but I no longer have access to test equipment, so troubleshooting will have to be limited to looking for components with apparent damage or poking around with a DVM. How does one access the circuit inside? It looks like the silver ring on the bezel may unscrew, but I didn't want to attack it with slip ring pliers until I know it's supposed to come off.

Thanks for any suggestions.

i've seen that issue twice already. EA4 isn't supposed to have moonlight mode

the issue stems from the poor thermal design of the EA4 and EA41. nitecore advertises them as "unibody" but in fact the LED's "star" (mcpcb) doesn't even sit on this "unibody". google the disassembly pix. there's a circular plate that pressfit into the body. that's where the LED mcpcb sits on. this plate has high thermal resistance to the body of the flashlight because it's a stamped part with jagged edges

so i think the LED gets overheated and the thermal cycling degrades the soldering between LED and MCPCB

the fix is actually very easy. no need to take the driver out. just re-reflow the XML over a hotplate

while you're at it you may want to improve the thermal resistance from the plate to the body

maxhawk · Jan 4, 2016

Re: Problem with my Nitecore EA4

I'd already pulled the driver when you responded. It's pretty obvious how bad the thermal coupling is between the heatsink/plate and body.

I tried Swan's suggestion to apply voltage directly to the terminals of the MPCB where the wires connect and the emitter lights up brightly as expected. This would imply that the connection between LED and MPCB is ok? I do have a hot air SMD rework station but I'm not sure how to heat up the plate from the top without damaging the emitter.

swan · Jan 4, 2016

Re: Problem with my Nitecore EA4

maxhawk said:
I'd already pulled the driver when you responded. It's pretty obvious how bad the thermal coupling is between the heatsink/plate and body.

I tried Swan's suggestion to apply voltage directly to the terminals of the MPCB where the wires connect and the emitter lights up brightly as expected. This would imply that the connection between LED and MPCB is ok? I do have a hot air SMD rework station but I'm not sure how to heat up the plate from the top without damaging the emitter.

Ok you powered the led directly the led seems to be fine-

What happens if you power the driver through the battery terminals ie hook up 4 x aa in series and attach wires with alligator clips thru the battery pcb, if it lights up as normal, this will tell you if its the battery circuit/tailcap problem.

maxhawk · Jan 4, 2016

Re: Problem with my Nitecore EA4

I figured out that the connection between the LED and MPCB was intermittent. When I applied voltage the 2nd time, the emitter was dim, and tapping on the lens made it shine brightly. Your initial diagnosis was spot-on. I dug up my extra-hands vise with alligator clips to hold the assembly level and heated the bottom for about 60 seconds with my hot air rework station set to the peak solder temperature specified by the datasheet. After it cooled I reconnected my power supply to the emitter and it worked normally with no intermittent issues.

I used some Arctic Silver 5 I had laying around from my last PC build to reapply thermal grease to the bottom of the MPCB as well as the edges where the plate touches the body. Boy it made a mess when I had to disassemble it again to install the plastic cover that goes over the PCB where the battery contacts are. In retrospect I could have left it off since it appears to be mainly cosmetic.

Light is functioning normally again. If it fails again I'll probably install an XM-L2 U3 like you did. They're fairly inexpensive if you choose the China ebay route.

Thank you, thank you, thank you!

Timothybil · Jan 4, 2016

Re: Problem with my Nitecore EA4

maxhawk said:
Light is functioning normally again. If it fails again I'll probably install an XM-L2 U3 like you did. They're fairly inexpensive if you choose the China ebay route.

Glad you got it fixed. You have inspired me to open up my E4 and see what is wrong inside. Number one son mixed a couple of alkaline cells with a couple of lithium primaries with the expected result. I don't think any of the goop actually got inside the pcbs, but I cleaned as much of the corrosion as I could off of the contacts and it still doesn't light, so it is worth the effort since it appears to be rather simple to do. If I do get it running again, while I have it open I may try to put a Nichia 219B in instead of the XM-L. If I do that am I going to overdrive the Nichia on High and Turbo?

swan · Jan 4, 2016

Re: Problem with my Nitecore EA4

Good news maxhawk-

I found excellent gains in output when i swapped out the original aluminium star [ only 1mm and not dtp ] with a thicker direct thermal path copper star [noctigon] topped with a xml2 u3 [ you can get brighter again u4,s now] but you need to remove .5mm from the base of the reflector to fit perfectly.

Now it puts out 1100lumens and 30kcd in turbo and 700 lumens on high.

My ea4 [about 3 yrs old?] has served me well running on eneloops, i first modded this one by removing the original emitter and dedoming it, but it was hulk green, tried an xpl but couldnt centre the led perfectly and did not like the tint v6 2b. So, as most would know it finally developed the infamous mushy rubber switch boot problem. So after ordering the new switch cover, i changed to the xml2 u3 1a which has a whiter tint. With the new rubber switch boot/push pin/ led its now ready for many more years to come and has become a sentimental favourite.

maxhawk · Jan 4, 2016

Re: Problem with my Nitecore EA4

Timothybil said:
... while I have it open I may try to put a Nichia 219B in instead of the XM-L. If I do that am I going to overdrive the Nichia on High and Turbo?

The 219B datasheet says absolute maximum of 1.5A while the XM-L2 will work up to 3.0A. I haven't measured the emitter's current in the EA4, but I suspect it's a bad idea to install a Nichia in place of the XM-L2.

Oh, and when reassembling and placing the driver and white plastic spacer back in the body, I used a large deep well socket that was large enough to contact the white ring while clearing the actual emitter and lightly tapped it with a hammer to push the assembly back into place. You can tell it's seated all the way when the battery PCB is flush against the black cosmetic piece.

Tac Gunner · Jan 4, 2016

Re: Problem with my Nitecore EA4

maxhawk said:
The 219B datasheet says absolute maximum of 1.5A while the XM-L2 will work up to 3.0A. I haven't measured the emitter's current in the EA4, but I suspect it's a bad idea to install a Nichia in place of the XM-L2.

Oh, and when reassembling and placing the driver and white plastic spacer back in the body, I used a large deep well socket that was large enough to contact the white ring while clearing the actual emitter and lightly tapped it with a hammer to push the assembly back into place. You can tell it's seated all the way when the battery PCB is flush against the black cosmetic piece.

As far as what the actual drive current can be of individual emitters, most LEDs can take more than what the manufacturer states. For instance Cree uses a standard 3 amp test current for all of their LEDs but in reality most can handle 2 or 3 amps more. XML2 can usually go up to about 5.5, XPL about the same, MT-G2 5 or 6, XHP50/70 6 or 7. The nichia is a lower current led but can still handle a small current boost from what I have read.

Overclocker · Jan 5, 2016

Re: Problem with my Nitecore EA4

half-assed engineering

i could cite a dozen more examples from ALL the major brands

easy to fix, right

Problem with my Nitecore EA4 (SOLVED)

maxhawk

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swan

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maxhawk

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swan

Banned

Overclocker

Flashlight Enthusiast

maxhawk

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swan

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maxhawk

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Timothybil

Flashlight Enthusiast

swan

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maxhawk

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Tac Gunner

Flashlight Enthusiast

Overclocker

Flashlight Enthusiast

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