D10 Contact issue (Pics included)

Hey all,

I love my D10 but intermittent issues with the piston drive was annoying me. I would clean the ring of the piston that makes contact with the brass ring every now and then but the problem got worse over time. It's been less than a year since I got the light.

I disassembled the light and I found the issue. Tarnished underside of the brass ring that makes contact with the circuit board and the outer edge of the circuit board itself is also tarnished. I had no way of seeing this until I decided to bust her open.

Here is the underside of the brass ring that makes contact with the circuit board when the piston is pressed down. Note the tarnished area.


Below is the circuit board that the ring sits on top of. Also tarnished.

I know electrical contacts will tarnish over time but this is a bit much.
I tried to clean the brass ring with alcohol, didn't work. I just scraped it gently with a knife and it got pretty clean.
I tried the alcohol then the knife with the circuit board but now that part of the board is not Gold colored anymore
The light seems to work ok now but if this happens again I'm not gonna be happy.

So design flaw or I just got unlucky?
Sorry for the poor pics...just bad lighting.


Ajay

Thanks for the info, I have a D10 which I EDC and like a lot. I'll have to keep my eyes out for this.

IIRC, a product named DeOxit-Gold would be the best product to put on the metal once you get it cleaned. It would help prevent the reoccurrence of the tarnish. I believe Lighthound sells it [a well known CPF dealer ].

Looks like what I saw when I worked on the old TV sets which used rotary switches in the tuners. They used to sell something called 'tuner cleaner' is a spray -- maybe you can still get it. The procedure was to spray into the tuner so it would hit the contacts, usually through some openings between the contact plates, and rotate the knob a few times. Usually worked. If you can get some electrical contact cleaner (no residue type) and rotate the ring around a few times I think it will probably fix the problem.

There was also a tuner lube available - silicon based, I think -- which protected the contacts from oxidation. I haven't been involved with that sort of thing for decades, but I'd bet such chemicals are still available, even if not labeled as specifically for TV tuners.

bluepilgrim said:

Looks like what I saw when I worked on the old TV sets which used rotary switches in the tuners.

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What a blast from the past!
Hmmm, what are the odds of something going wrong with this switch with dozens of contacts making and breaking with every change of the channel?
Lots of folks lamented the loss of tubes and analog circuits, but I don't miss those heaters at all!

Oh yeah, nice detective work Ajay. Now that you know the issue keeping it from happening again should be easy. I'm just thinking out loud here, but it seems like if you lightly tinned the contact points with a bit of solder you might avoid the oxidation or whatever that is on there. I can't tell if that brass ring is already tinned or not. Just thinkin..

Maybe try a pencil eraser next time?

How about some fine steel wool or fine grit sandpaper gently rubbed on the tarnished areas?

HarveyRich said:

How about some fine steel wool or fine grit sandpaper gently rubbed on the tarnished areas?

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ACH! Not steel wool. It could get into the circuits and short them out.

Contact solvent and a cotton swab should be enough. Or maybe even a little (!) WD40 on a swab -- I've used that in similar circumstances.

Good job Ajay.
I would like to see these rings gold plated.

sparkysko said:

Maybe try a pencil eraser next time?

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i have found that to work on contacts pretty well.

of course i heard it here.

Thanks for the comments folks!

I have electrical contact cleaner and I never even thought about using it
So next time I have an issue with the PD system I will do the following:

User pencil eraser
If fail then - Clean with electrical contact cleaner
If fail then - gently sand brass ring and lightly tin the circumference of the circuit board with solder.




Yeah I hope the newer D10's wil have some Gold in there or something to prevent this problem. So what do you guys think design flaw or bad luck?

Thanks for the input everyone.

Ajay

After getting them clean you can use Deoxit to prevent future oxidation, it is one of the best products there is for contacts.

Hi Ajay,

How did you take out the brass ring?

Thanks

kimck99 said:

Hi Ajay,

How did you take out the brass ring?

Thanks

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Learned how to from this video:
http://www.youtube.com/watch?v=cVlBqFSgAxE

Good luck with your disassembly. FYI the brass ring will get a bit scratched up and probably void your warranty.

Thanks. I'll give that a try.

I don't believe that to be tarnish, but smashed dirt, rubber, and lube. The O ring has to degrade over time. I would be that its most of the black stuff.

batmanacw said:

I don't believe that to be tarnish, but smashed dirt, rubber, and lube. The O ring has to degrade over time. I would be that its most of the black stuff.

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Interesting hypothesis but that stuff was hard and non greasy. I had to scrape it off with a knife.

Ajay said:

Interesting hypothesis but that stuff was hard and non greasy. I had to scrape it off with a knife.

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Lube and rubber can harden. Especially when smashed repeatedly over time.

Tarnish does not just happen. I have brass that has been sitting on a shelf in our cold machine shop for years without tarnishing to black. Physics still applies here. How would actual tarnish develop in a closed system like this where there is no contact with salts and oils from your body to help the process along?

If the head is usually tightened, the ring will be engaged. Daily vibrations and change in temperature will cause minor amounts of abrasion that can build up over time.

If the ring turns when turning the tail, then it's direct abrasion.

Hardening lubricant is a possibility.

Also, if current is passing through the interface, there could possibly be unintentional electroplating of one metal onto the other.

I've deoxit gold after a good cleaning, and it's been just fine for about a year.

Ajay said:

Yeah I hope the newer D10's wil have some Gold in there or something to prevent this problem. So what do you guys think design flaw or bad luck?

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Having gold would be cool! But did you see the price of Au today? In terms of dollars it's at an all time high, not to mention other currencies are not far behind either.