# Brass or gold wire



## Darkness Falls (Mar 25, 2015)

I was finishing up dismantling a dvd drive out of a desktop PC when I noticed four thin gold colored wires connected to the reader eye. I was wondering if someone here knew if these were gold, gold plate, or brass? I don't have any Nitric or other testing equipment so I must rely on the communities' expertise and visual aids.


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## Smack (Mar 25, 2015)

Brass, copper or even could be beryllium, a nitric test will tell you.


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## shmandi (Mar 25, 2015)

I don't see any reason for using gold or gold plated. Different wire than in coil (copper) is used as it acts like spring for lens. Probably is some copper alloy.


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## ssabovic (Mar 25, 2015)

smack,
it may be beryllium/copper (contain 2.5% of beryllium rest is copper it has redish color),beryllium is gray color, and beryllium in ceramics is white becouse it is beryllium oxide.


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## g_axelsson (Mar 25, 2015)

It may be anything that is suitable for making a spring. There have been CD:s made for over 25 years from various manufacturers with different products in various states of development / evolution. I don't think there is a standard material for this spring that every manufacturer uses.

As it is a spring, have you tested it with a magnet? If it is magnetic and yellow then it probably is gold plated steel.
Gold plated to reduce the skin effect and increase conductance and frequency response in the servo loop that controls the position of the lens.

Göran


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## rickbb (Mar 25, 2015)

I'm guessing brass, used as a slide rail so the lens can slide in and out to keep in the "track".


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## g_axelsson (Mar 25, 2015)

rickbb said:


> I'm guessing brass, used as a slide rail so the lens can slide in and out to keep in the "track".


The picture is of the lens mount, not the whole laser pickup. The lens isn't sliding, it is soldered to the spring wire and the wires are used for supplying the two sets of coils with current.
The four wires forms a rigid construction that still allows up-down and left-right movement of the lens without it twisting. Up-down for focus and left-right for keeping the track under the lens.

It's an amazing construction that can keep focus within 1 um and tracking within 0.1 um while the disk wobbles above it at a speed that nearly rips it apart from the centrifugal forces. All for a few dollars worth of components. :shock: 

Göran


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## Palladium (Mar 25, 2015)

g_axelsson said:


> It's an amazing construction that can keep focus within 1 um and tracking within 0.1 um while the disk wobbles above it at a speed that nearly rips it apart from the centrifugal forces. All for a few dollars worth of components. :shock:
> 
> Göran



Great! All i keep thinking about now is that loose bearing i have on my mowing deck of my lawnmower! :mrgreen:


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## Darkness Falls (Mar 25, 2015)

g_axelsson said:


> rickbb said:
> 
> 
> > I'm guessing brass, used as a slide rail so the lens can slide in and out to keep in the "track".
> ...



Yes! This is a perfect description of it. It is not magnetic and the color is off in the picture too. In person, it looks like gold or high polished brass.


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## Darkness Falls (Mar 25, 2015)

Palladium said:


> g_axelsson said:
> 
> 
> > It's an amazing construction that can keep focus within 1 um and tracking within 0.1 um while the disk wobbles above it at a speed that nearly rips it apart from the centrifugal forces. All for a few dollars worth of components. :shock:
> ...




That sounds like Russian roulette via lawnmower. :lol:


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