Dark Spot on LED

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Vincent7
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Dark Spot on LED

 Hello everyone. I recently noticed this dark area on one of the led's in my MF01 mini. Do you think it's a damaged dome or just a manufacturing defect? The light functions properly and the beam isn't affected. ( Top left in image ) I tried brushing it very lightly with a small brush, but it doesn't come off. Thanks

Nooner
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Kinda looks like the thermal paste seen elsewhere. Probably that, no?

Try a gentle rub with some isopropyl alcohol.

Vincent7
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Thanks Nooner, I’ll give it a try with a cotton swab.

Helios azimuth
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Did the alcohol remove the spot?

Vincent7
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I wasn’t able to remove it. I tried alcohol on a Q tip but it wouldn’t budge.
I thought it looked like thermal paste also, but it could be something else. When the light is fully assembled, and on its lowest output, I can see it easily on the led, through the optic.
It doesn’t appear in the beam however.

djozz
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Maybe the dome of that led was touched with something hot that melted the silicon a bit. The spot seems to look like white or transparant in which case it could likely live there without trouble (only little light/heat absorption), if it was dark coloured it was a burnt dome waiting to happen.

Vincent7
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Thanks Djozz, it does look white or grey colored. I’ll keep an eye on it, and if it get worse I’ll be sure to post a new picture
of it. I appreciate the help.

Chatika vas Paus
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Sometimes it happens that something is glued to the lens and cannot be removed with a cotton swab or isopropyl. I usually first check under a 10x magnifying glass what it is.
You can try to scratch it with a super thin pin, but you have to be very careful not to damage the led even more.

Just saying.

Don’t do it if you’re not sure of your hands.

kiriba-ru S2+ and S21a spacers are available in EU. PM me. A few details here

datiLED
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From the picture, it looks like solder paste. Saturate a Q-tip with alcohol and let it sit on the spot for a few minutes. It may soften enough to be removed. Dried out solder paste is tough to remove from surfaces. Be careful not to damage the dome!

Jerommel
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It looks like the grey gunk that’s also on the PCB.
Maybe possible to peel it off with a pointy but not too sharp knife.

datiLED
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Jerommel wrote:
It looks like the grey gunk that’s also on the PCB. Maybe possible to peel it off with a pointy but not too sharp knife.

Jerommel, you got it! It is silicone.

Vincent7
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Thanks for the suggestions. I’ll give them a try.

Jerommel
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Vincent7 wrote:
Thanks for the suggestions. I’ll give them a try.

Good luck !