Arc LS inductor ???

ZuluWhiskeyFox

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I am repairing an Arc LS and found that the inductor is damaged. Has a large piece missing. The colored dots are gone. So what I'm wondering is what value should the replacement be? Is there a value that would be better suited for a light that will be boosted to the 660ma range? (has a second .15ohm resistor on board) And lastly does anybody have one they wish to sell me?

cheers,
zwf
 

shiftd

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zulu

as long as the wires are remain intact, you should be fine. I used to have arc LS with cracked inductor with its top part got removed, exposing the wires, but it still works fine. are you sure the problem come from the inductor?
 

dat2zip

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Any cracking or pieces missing off the inductor reduces the Saturation or working range of the converter board. Yes, under a fresh battery condition you could still be fine, but, as the battery voltage drops the inductor current rises. You will see the inductor saturate near the bottom end. Boosting or raising the output current puts more demand on the converter and inductor and means the inductor will saturate sooner. While the converter may still operate in a less than happy state and remain in regulation you can bet that there is excessive heat generated under these conditions.

I would recommend an exact replacement which is the Coilcraft DO1608C-332. It's a 3.3uH inductor.
 

ZuluWhiskeyFox

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Thanks guys. My main reason for thinking the inductor is at fault is the voltage to the lux is only slightly increased above that of the battery voltage under load. Battery voltage under load is 2.96v and to the lux it's 3.01v So from this I surmised that the circuit is basicly working just not up to par.
 

dat2zip

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Zulu,

Hmm, that sounds much worse than that. I can't imagine 3.01V to the LED unless it's running 20-200mA. Under any drive level I would expect a Vf of 3.3-4V. Somethings not right...

At 3.01V I would take it the light is very dim.
 

ZuluWhiskeyFox

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Yes, very dim. And with the inductor broken the way it is I figured replacing it would be a good place to start. Are there any other suggestions on what it might be?
 

dat2zip

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It sounds to me like the IC is shot and you are in DD mode. The battery flows through the diode to the LED.

But, in DD mode the LED voltage would be lower by a few tenths of a volt from the battery. Do you have these numbers backwards?

If so, the IC is shot. You would in this case need to replace the LT1618 IC.

If the inductor is totally shot and it behaves more like a resistor than an inductor you could have damaged the IC.

Replacing the inductor at this point probably won't bring the circuit to life.

I'm just guessing tho....

Wayne
 

ZuluWhiskeyFox

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I double checked the voltages and I do have it the right way around. Vin is lower than Vout. My meter also has the ability to measure frequency. So I also measured across the inductor. Meter read .669 Mhz So it appears as though the IC is doing something. Don't know if its the right thing though. The diode still tests as one. there are a couple of caps and they test as such. The larger one is 10uF.

/ubbthreads/images/graemlins/confused.gif

zwf
 

shiftd

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what type of Arc LS you have zulu? May i suggest changing the whole arc LS board all together for something more efficient and nicer than the current one?

I currently running mine from a minipro, but you can also use Madmaxes or BBs.
If yours is the first rev body with 2 parts, you might want to try to contact roth to make you custom sink to house the BB or MM. If yours is the latest rev with one part body, try my penny mod /ubbthreads/images/graemlins/wink.gif

in any case, if you still prefer the old board, i wish you good luck on reviving the converter.
 

dat2zip

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Hmm, it looks like it's running and the internal switch is not fried yet.

You might want to check the soldering on the IC pins. Maybe, the Power GND pin is not soldered down causing a weak converter operation.
 

ZuluWhiskeyFox

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OK checked the soldering first visually with 12x loupe. Saw that some of the soldering was questionable. So I gave everything on the board a once over with the soldering iron. That did help emensly. However we are still not up to the desired current. It's now hovering in around the 350ma range to the lux. This is with a second .15ohm resistor beside the original. So I'm still thinking the problem is that cracked inductor. Yes, No? So does anybody have one they could sell me?

cheers,
zwf
 

jamaica

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[ QUOTE ]
ZuluWhiskeyFox said: So I'm still thinking the problem is that cracked inductor. Yes, No?

[/ QUOTE ]
Yes.
[ QUOTE ]
So does anybody have one they could sell me?

cheers,
zwf

[/ QUOTE ]

DigiKey - Panasonic ELL-6PV3R3N for $US1.38 ? (Electrically good, but it's 6x6x1.8mm in size, versus the 6.6x4.5x3mm of the original Coilcraft. Not having the board on hand, I can't see if the replacement would fit.)

Best,
Jamaica
 

dat2zip

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zwf,

Send me an email.

I'll toss one in the mail to you.

Wayne

theledguy at theledguy.com
 

ZuluWhiskeyFox

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Update: I received an inductor from Dat2Zip, Thanks Wayne. The new inductor made all the difference in the world. Now she be very bright. Current is up a little over 600ma. With a TWOK and an IMS reflector along with a UCL the light really screams.

cheers,
zwf
 
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