Repairing a Fenix LD-01, need some help

Preamp

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Hello everybody.

This is my first post on this forum. I've found quite some good informations in here, so I thought I'll just sign up and ask you pro's for some help...

I am trying to fix my three years old Fenix LD-01 for the second time now :(. The error is basically the same, the solution, obviously, is not. But let's start from the beginning:
When the Fenix stopped working for the first time, I could only get some light out of it twisting and pushing/bending it quite hard. My first thought was that the lower case didn't make a good contact to the PCB, so I added some solder to add up some height to the contact.
Unfortunately this made things only worse, because the irregular surface added lots of switch bounce, driving the mode selector mad :oops:.
So I went on and completely disassembled the Head. I cleaned the electronics from epoxy, took the PCB stack apart, and resoldered each and every component. After putting everything back together, it actually worked fine again. Up till now, about three weeks long.

The actual problem now is this: When I turn the LD-01 on, it eventually starts to flicker uncontrolled for a couple of seconds. During this flicker, it manages to cycle through the modes until it ends in high power mode, where it continues to work as expected. Turning it off and on again, restarts the flickering process until it ends in high power mode again.

So here I am now, ripped the whole thing apart again and wired it up do so some testing. The solder joints all seem to be OK now, I can't produce any misbehavior through knocking or pushing anywhere on any of the parts. I noticed that the core of the coil is broken, though. So I replaced it with another coil I had lying around, for testing purposes. This stopped the inductor whine (since I used a coated one ;)), but nothing else changed. Tried the same with the capacitors, but to no extend.

A bit frustrated and not knowing what to do anymore, I started drawing a schematic, as good as possible. While measuring the connections, I tried to check for bad vias, but everything seems fine to me.
Maybe some of you guys recognises which kind of driver is used and/or has some tips for me what else to look for.


Thanks in advance and kind regards,
Lasse


ld01_schem.gif


fenix_ld01_inside.jpg
 

Bullzeyebill

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Not saying that this is the case, but have you checked the tailcap electrical contact ring? It has two indents in it too allow for tightening, and loosening. Many Fenix's have had the issue of the contact ring unscrewing a little and causing finicky contact with the end of the flashlight body.

Bill
 

Preamp

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No, I did not check it. But since I have the electronics laid out on my bench, soldered wires to the battery contacts and connected them to a power supply, I can exclude it for now, I guess.
 

Dubois

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Not saying that this is the case, but have you checked the tailcap electrical contact ring? It has two indents in it too allow for tightening, and loosening. Many Fenix's have had the issue of the contact ring unscrewing a little and causing finicky contact with the end of the flashlight body.

Bill

Are you thinking of the LD10, rather than the LD-01? The "tailcap" on the LD-01 is essentially the body of the light, and is over an inch long - I can't see any contact ring with indents like on a bigger light down there, just the spring.
Sorry I can't help OP.
 

HKJ

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I cannot tell you what the fault is, but I can give your a good idea about how it works (Maybe you have already figured that out):

The PCB with the inductor is a boost converter that increases the voltage up to led level, i.e. 3.5 to 4 volt.
On the other board you have a voltage detector (marked 22), a microprocessor (unmarked chip) and a transistor (marked AGSE).
C3 and C4 is used to maintain power to the microprocessor when you turn off/on to change brightness level, this fast power drop is detected by "22" and signalled to the microprocessor.

You can check that the boost converter has a stable output voltage.
The wire from "22" to microprocessor must have a stable voltage, until the voltage drops, then it must change to another voltage.
 

Preamp

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HKJ,

thanks for explaining the circuit. I was quite sure about the boost converter and the FET, the microcontroller was a careful guess, but I had no idea about the voltage detector.
The wire you mentioned is stable at 0V when the circuit is running in high power mode. In the 'flicker mode' this one is also flickering :(.

If I am assuming correct, I could simply leave the first board out and connect the second one directly to 4V, right? I'll try this tomorrow.
 

HKJ

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If I am assuming correct, I could simply leave the first board out and connect the second one directly to 4V, right? I'll try this tomorrow.

I will recommend including a resistor in series with the power supply, maybe 1 ohm. This way you avoid driving the led into a very high current direct drive mode.
 

Preamp

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My bench supply is current limited. The whole circuit uses about 800mA in high power mode, so I'll start out with something like 500mA.

Do you have an idea which type of boost converter might be used here?
 

HKJ

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My bench supply is current limited. The whole circuit uses about 800mA in high power mode, so I'll start out with something like 500mA.

500mA is a bit high, remember that the boost converter will nearly triple the voltage, i.e. you only have about 270mA for the led and processor.
Many bench power supplies is a bit slow in current limiting, i.e. you might get a current spike, it is much safer to include a resistor in the circuit.


Do you have an idea which type of boost converter might be used here?

I do not know what chip is used.

My explanation was based on your schematic, not on studying the internals of a LD01.
 

Preamp

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500mA is a bit high, remember that the boost converter will nearly triple the voltage, i.e. you only have about 270mA for the led and processor.
Many bench power supplies is a bit slow in current limiting, i.e. you might get a current spike, it is much safer to include a resistor in the circuit.

Okay, I'll be on the safe side. Thanks again!

I do not know what chip is used.
My explanation was based on your schematic, not on studying the internals of a LD01.

I thought you might know some commonly used regulator chips and could make a quick guess based on the pinout... :eek:
 

Preamp

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Okay, the test ran fine. So at least this part is working as expected :thumbsup:.

Now to the regulator part. I connected a small 6V bulb as dummy load and it behaved like before, flickering for a couple of seconds and then running fine. I did this test with the 10uf-cap replaced by a 4u7 electrolyte. When putting everything back to 'stock parts', the regulator refused to do anything :(.

So I removed all the components from the board and cleaned it. Didn't find any hidden vias or tracks that might have failed, though. Suspecting the regulator chip itself to be errorneous, I went on and scraped the black epoxy off of its top to reveal his name. After complaining that I don't own a good microscope anymore :hairpull:, I put the chip on my scanner and actually managed to read the marking :cool:.

The used regulator is an AIC1610. I drew it on top, so here's an updated schematic:


ld01_schem2.gif



Maybe if I manage to be really bored, I try to hook up the circuit on a 'breadboard' to make sure that it's not a faulty PCB. I still guess this might be the possible, since it does have to withstand some pressure... But a defective IC seems more likely to me.
Now where to get a new one...? :shrug: Seems quite unobtainium :(
 
Last edited:

Preamp

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Damn thing :mad:. After thoroughly removing the epoxy residue between the legs of the IC I re-populated the board and tested again - everything fine. So I put the whole thing back together. The light is working better than before now, but not as good as it should. It lets me cycle the modes and does not flicker anymore, but I have to twist the head on really tight and occasionally it simply stops working. I'm already tempted to scrap that thing... :(
 

tam17

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Preamp, your effort is just astounding. I don't remember that someone on the forums gathered so much information on LD01 circuit than you did in these few days. I owned two LD01s and one of them is now my EDC, so I know the measures of those circuit boards, they're TINY.

Maybe it's time to put your little companion to rest...

Cheers
 

Preamp

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Thank you for your kind words.

Guess that's what I'll be doing. But what is buggering me is this: If I put the LD01 to rest, what will be it's successor? I do want an AAA for EDC, so the LD01 is the perfect fit! I didn't find anyhing equal yet. Guess I'll have to dive into bunches of reviews again...
Or buy another LD01 and pray that it'll last longer :sigh:.
 

tam17

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IMO the only light worth considering to replace the LD01 is another LD01 (updated of course, as I can see yours is an older XR-E version). Newer XP-G R4 and R5 versions will give less throw and tend to produce a greenish tint, but their runtimes are way better. I'd never give up my E05, either.

Cheers
 

Preamp

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Or a thrunite TI.

Don't like the regulator of the TI, as its brightness drops with battery voltage. The Ray S20 or the Titaner ET20 would have been nice, but they're not available anymore as it seems. Guess I'll have a look at the Fenix LD15 then.

And one day I'll build a completely new driver and resurrect my LD01! :rock:
 

tam17

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Guess I'll have a look at the Fenix LD15 then.

Believe me, LD15 is nowhere near LD01. It lacks Medium mode (a big minus IMO), heats up quickly in High mode and tint (at least on mine) is sickly greenish :green:, almost unbearable in Low mode due to tint shift. It's very compact and dead simple, though.

Cheers
 
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