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What are PCBs?

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Post time 2020-5-15 01:35:57 | Show all posts |Read mode
These chemicals were banned in the U.S. in 1979 amid suggestions that PCBs could have unintended impacts on human and environmental health. From the 1920s until their ban, an estimated 1.5 billion pounds of PCBs were made for things such as microscope oils, electrical insulators, capacitors, and electric appliances such as television sets or refrigerators. PCBs were also sprayed on dirt roads to keep the dust down prior to knowing some of the unintended consequences from widespread use.

Prior to the ban in 1979, PCBs entered the air, water, and soil during manufacture and use. Wastes from the manufacturing process that contained PCBs were often placed in dump sites or landfills. Occasionally, accidental spills and leaks from these facilities or transformer fires could result in PCBs entering the environment.

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Post time 2020-5-15 01:36:40 | Show all posts
PCBs can degrade or breakdown in the environment, but the process greatly depends on the chemical makeup of the PCBs. The degrading process also depends on where the PCBs are in the environment. Typically, PCBs are either broken down in the environment by sunlight or by microorganisms. Sunlight plays an important role in the breakdown of PCBs when they are in the air, shallow water, or surface soils. Microorganisms, such as bacteria, algae, or fungi, biodegrade PCBs when found in soil or sediments.

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Post time 2020-5-15 01:36:46 | Show all posts
Because PCBs exist in sediments, scientists need to determine if it is better to dredge and remove contaminated sediments from waterways or if it is safer to leave the sediments in place and cover with clean sediments, allowing them to naturally biodegrade. A cap or barrier can also be placed over contaminated sediments to prevent them from entering the environment. There are environmental, human health, and financial concerns with all of these alternatives.

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Post time 2020-5-15 01:37:06 | Show all posts
The best example is the HP brand. This brand / manufacturer when sell their electronic electrical equipment they do not usually provide “Service Manual”. The service manual is the very comprehensive file / folder containing details of schematics, PCB, Parts used, Blueprint, wiring diagram, error codes, LED indicator meaning to check for the Indicator LED status, Calibration procedures etc.

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Post time 2020-5-15 01:37:13 | Show all posts
Generally, the dedicated electronics hardware including professional PCBs and PCBA developed by specific brands like HP/ Agilent/Key-sight, Rohde & Schwarz, Tektronix require high level of engineering skills when it comes to repair and maintenance. As the hardware service manual and part numbers are nearly impossible to find on internet. Hence if the product is under warranty then immediately contact supplier otherwise check the online blogs/forums where people have shared their success of repair/services on internet.

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Post time 2020-5-15 11:47:27 | Show all posts
WTF?.  In Some cases, PCB = Printed Circuit Board.  I hate acronyms BTW.  Lazy people use them.
Thanks  [url=http://www.orangepi.org/orangepibbsen/static/image/smiley/default/biggrin.gif]http://ww

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Post time 2020-5-16 20:35:28 | Show all posts
To legend the electronic part location, the complete structure is covered and plated with silkscreen and non-conductive solder mask.  Components are usually mended onto the board to both electrically connect and mechanically fasten them to it. It is present in all electronic products, including the simplest products. These chips have copper lines, fiberglass, and other metal components protected with a patch cover and epoxy.

Alternating layers of conductive copper build the printed circuit board with sheets of non-conductive covering material. The inner layers of copper are cut that leaves the designed area of the copper so that circuit component can connect. Once cut insulation layers is covered to the layers of copper until the board completion. The experts add the components to the outer layer after the completion of all layers of circuit board assembly.

https://www.pcbonline.com/PCB-FAB/Hight-Frequency-PCBs
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