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Inside High End Equipment


STC

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29 minutes ago, Ron Scubadiver said:

A controversy exists as to whether a photograph of a 3 dimensional object comes under fair use or not.  Photographs of the Eiffel tower taken at night are said to violate the copyright of the one who designed the lighting.  It's the same situation regarding the Seattle Space Needle unless the tower is just part of the skyline.

The New York Port Authority reckons they own the skyline. Needless to say, there are those who disagree.

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23 minutes ago, marce said:

Would be better, but its not the true way, P to P is far better for interference and EMC problems...

I'm aware of extreme applications where a PCB won't do, but audio is not among them.

 

23 minutes ago, marce said:

Hand wired in total darkness by dedicated masters of the soldering iron...

Japanese virgins, presumably.

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  • 2 months later...
5 hours ago, marce said:

Ahhh nothing beats the gentle aroma of frying PCB's. We got a VME rack back once, the end user plugged the mains into the keyboard connector, managed to connect it to the main 12V supply, results were interesting...:D

At least fault finding is easy when all you have to do is follow the black trace. Reminds me of my days repairing photo flashes. 1000 V and as many amps down the wrong path never did any good. It's also the only job I've had where sunglasses were standard issue.

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21 hours ago, STC said:

Those China stuff are meant to be used with 220V supply and our supply is usually about 245 to 250V. Although, the official rating should be 230V.

The mains voltage in continental Europe may legally go as high as 242V while in the UK the maximum is 254V. A 230V rated device for the European market must work correctly also with UK voltages. Designing a device for 220V only today is stupid, and selling it in Europe is probably illegal.

 

Regardless of the intended operating voltage, the amount of damage seen in those photos is unacceptable as a result of a slight overvoltage on the mains input. It's not hard to give the power supply a little extra margin.

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8 minutes ago, gmgraves said:

I don't think it was. I think the Phillips/Magnavox FD-1010/CD-101 was the best CD player in the early days.

For a while, the CDP-101 was the only CD player on the market. It was, by definition, the best. Yes, the Philips players were better in most every way (I prefer the look of the Sony over the Philips CD100) once they became available.

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15 hours ago, STC said:

OT. I used to love bonsai until a family friend got one in his house. I thought bonsai trees were natural miniature trees like little people until he started trimming the branch and roots to keep their growth retarded. I thought it was cruel. Pointed out that I couldn't appreciate the beauty anymore. At one time it was footbinding in China and neck lengthening in Burma. The world is crazy. 

Ever heard of bonsai kittens?

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38 minutes ago, STC said:

Inside Naim NACA 5 speaker cables. Notice the broken cores. Should this be resoldered?  Will doing proper termination affect the SQ. Or should I ask the manufacturer why this is so? Or should I care since it made no diff to my ears?

It probably makes no difference, but it's still shoddy work.

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  • 3 months later...
40 minutes ago, STC said:

Just like how the green pen did?  Still dont’t understand why green. And one used blue. CD laser is red.  And they make these for believers. Faith cannot be questioned. 

Neither makes sense, but the LED makes even less sense. The green pen treatment was intended to stop scattered reflections of laser light escaping through the disc edge. If this really was a problem, at least treating it at the supposed source had some merit.

 

Now how is an LED supposed to help with scattered light? Are they hoping the green case will absorb light of other wavelengths? Supposing it does, it's still not going to make any worthwhile difference. If you paint a square inch on a wall black, does the room get darker overall? Do they somehow believe that the green light will "neutralise" the red light from laser? Confused, perhaps, by some high-school chemistry experiment involving acids, bases, and a pH indicator?

 

If stray light were a concern, painting the interior in Vantablack would fix it.

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9 hours ago, STC said:

These LEDs not connected to anything. They just lit up next to the laser shining the transport mechanism. I am only guessing that the green light mixes with stray red somehow makes them not to have any influence in the data picked up by the laser unit from the CD itself.

That isn't how light works. As for CD pickups in general, the photodetector is likely most sensitivite around the wavelength of the laser and relative insensitive to green light. Moreover, due to the construction of the optics, only light from a small angle reaches the detector in the first place.

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1 minute ago, botrytis said:

Photodetectors are usually not keyed to specific wavelengths, they can pick up any wavelength. It is more to do with the small angle as you said, mansr.

The datasheets say otherwise. Here's the sensitivity of a random photodiode from Vishay:

image.png.a7140dc58df2571c609c259ec9920197.png

 

A CD laser has a wavelength of 780 nm, close to the sensitivity peak of this photodiode. For green light of 550 nm, it is only half as sensitive. Contrast that with this one:

image.png.78771ed573c3e092151759969a7e3a24.png

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