Component stripped from driver.. Klarus Mi1C

Flashlight Modding and DIY Parts
1

Hey, i was gonna do a LED and optic swap on my Klarus Mi1C, and i decided to take out the driver too (to have a look).
So i unscrewed the plastic driver retainer disc, and i stripped off a part…

Can you spot the empty space?

This is what came off.
The capacitor next to it also came off, but i could solder it back on.
The thingy that came off lost its 3 legs in the accident…
The legs were still on the PCB…

It says “SAOH” or “SA0H”.

It’s probably a transistor, maybe a FET.
It’s only 2.7mm wide.
I need a replacement.

2

would help to see what it is connected to on both sides
most likely FET but could be also a voltage regulator

n-fet you can usually easily pick drain and one of the gate resistors connected to ground
same with p-fet but to battery +

could be also a transistor in the feedback loop

sot23 is 2.9mm wide

3

There are what looks like capacitors connected - one on each side - to the pads of this mystery part. The “top” leg and the “bottom left” leg of the part are connected to opposing ends of the (capacitor?) on the left, and the “bottom right” leg is connected to the (capacitor?) on the right, the opposing side of which is connected to the spring pad. The “bottom left” leg trace also seems to go to the ground ring and some other components.

4

yes for a FET the gate on ground makes not really sense

5

I killed my Mi1C the same way. :frowning:

6

So you need the same part?

7

But this light takes the battery in reverse position.
So the spring is the minus and the body is plus.

8

The through holes on the other side are under the inductor.
So i can’t see where it goes.
I will upload a picture of the other side.

9

While unscrewing I stripped a capacitor and almost stripped one more part. I think the same as you did, but maybe the 5-legged one. Will check later. The legs got much longer than normal, but I didn’t see any discontinuity.
I soldered the capacitor back, moved the almost-stripped component back to place, the driver was dead.

10

Seiko / Ablic S-1206 is a match for SAOx: a 2.5V LDO.
Bottom left pin = ground would fit too.

11

Okay, i took some pics.
I removed the inductor to show the through holes from the ‘mystery component’.

Apparently the through holes go nowhere.
Very strange.

And another pic from the spring side:

I made blue what tests as continuous, but it’s strange if they’re really the same, because otherwise they could have bridged it right from the minus spring. (Again, the spring is minus, battery goes in bottom first).

12

Okay, now we’re getting somewhere.
Thanks! :+1:

what does LDO mean and what does it do?
EDIT: I see it’s a Voltage Regulator.

13

Low-dropout_regulator

This board might have more than 2 layers so the through holes could have a purpose.

14

Yeah, that crossed my mind too, but i can’t see a hint of another layer…
But it would make sense.

15

Is this the same?

or

If not, can someone help me find one?

16

Those should work but you should make sure it’s indeed an LDO: Vin (pin 1, top) should be connected to the battery plus; the output (pin 3) probably connects to pin 1 of the µC (a PIC12F1840).
If that’s the case, it’s pretty much confirmed it’s an LDO.

I’d try and get a replacement somewhere that doesn’t take a month to ship though.
e.g. https://www.conrad.nl/p/microchip-technology-mcp1700t-2502ett-pmic-voltage-regulator-linear-ldo-positief-vast-sot-23-3-651410
or maybe you have a local shop.

PS: I think Arrow has free shipping right now, might be the fastest & cheapest option of all

17

Hmmm… The other 3 legged component “D19HJ” is connected pin 1 to plus and pin 2 (left) to minus.
Pin 1 of the “SAOH” is not connected to plus.
(see next posts)

wait, i’ll do some testing, be right back.

18

Oh, there’s some confusion here.

The S-1206 datasheet has pin 1 on top, but common SOT-23 nomenclature has it at bottom left:

19

Uhm… so… pin 1 (bottom left) of “SAOH” is connected to minus.
So it’s not a positive LDO, correct?

20

No, that’s the same as ground, so B+ and LDO output are above that. (=positive LDO)
But make sure pin 3 (top, as in the diagram above) is connected to the battery +.