Is there a difference between US/Canada/europe and china for marking polarity? - Page 1
Forum section: electronics / general

author: XOIIO
author_rank: Super Contributor
timestamp: January 04, 2014, 11:05:13 am
content: Hey all I was just wondering, does china perhaps use different symbols or something to mark polarity in their products? I ask because in almost all (if not all) of the LED light teardowns I have seen on aintbigaintclever or connor worlf, they have positive and negative switched around on the circuit board and wiring and it seems really odd, especially since the lights came from different sources. This was on the ebay cheapie ones, but still, something like that seems pretty odd to be so consistent between them.

author: tom66
author_rank: Super Contributor
timestamp: January 04, 2014, 11:35:21 am
content: Do you mean things like negative half moon on capacitor is wrong way around? ASUS, motherboard manufacturer, is very found of doing that too.

author: XOIIO
author_rank: Super Contributor
timestamp: January 04, 2014, 02:09:23 pm
content: Quote from: tom66 on January 04, 2014, 11:35:21 amThe whole silkscreen is off, they have the positive from the power supply going to negative, and vice verca, I never really got a look at the silkscreen for the LED's since there are usually a lot of them so I don't know if it is backwards or not for that too. The wires are correctly colored though.That's weird that ASUS would do that.

author: Unknown
author_rank: Unknown
timestamp: January 04, 2014, 06:02:20 pm
content: Quote from: XOIIO on January 04, 2014, 02:09:23 pmI don't think that + means - and - means + in China. It will be because of either no QA processes or because some cocked up the PCB design.

author: hiddensoul
author_rank: Regular Contributor
timestamp: January 05, 2014, 10:55:45 am
content: Quote from: Lurch on January 04, 2014, 06:02:20 pmYeah I agree someone stuffed up the Silkscreen overlay in the PCB design and after making a product PCB of (insert number of thousands here) it was easier to just leave as it was not really meant to be seen by a consumer anyway

author: Kohanbash
author_rank: Regular Contributor
timestamp: January 05, 2014, 02:08:59 pm
content: While not a silk screened object the wire colors for PWR and GND are different based on your country.For example (these are usually correct but watch out for people doing things backwards) in the USA PWR=red and GND=black. In some other parts of the world PWR=brown and GND=blue or grey.

author: nctnico
author_rank: Super Contributor
timestamp: January 05, 2014, 02:28:20 pm
content: I think I still have a Compaq PSU somewhere on which red is 12V and yellow is 5V. Very confusing. At my former employer an intern used red for ground and brown for plus. The boss thought it wasn't important enough to change it. That has cost a lot of boards...

author: Kohanbash
author_rank: Regular Contributor
timestamp: January 05, 2014, 02:33:49 pm
content: Quote from: nctnico on January 05, 2014, 02:28:20 pmSwapping the voltages. Why do people do these things. ahhh.For a while Dell was also swapping pins and not using the standard ATX power supply pinout but using the standard ATX connector.

author: XOIIO
author_rank: Super Contributor
timestamp: January 05, 2014, 05:23:49 pm
content: Quote from: nctnico on January 05, 2014, 02:28:20 pmOh my god, that is just evil, I mean damn. Guess the head honchos don't really care about that sort of stuff just profit margins and how long it would take to fix somethingI would have returned that PSU the second I saw that, sheeshQuote from: sdk32285 on January 05, 2014, 02:08:59 pmI have a feeling that may be it because it was on many different boards, though they could all just be from one warehouse and one designer who messed it up, who knows how the industry for cheap ebay items in china is organised.

author: SeanB
author_rank: Super Contributor
timestamp: January 05, 2014, 05:30:31 pm
content: Just worked on a cheap Chinese LED light, and the wiring is correct. Be careful of 3 phase equipment from PRC, there they use a green as an active phase. I have seen many variations on this as well with a pre-installed PRC plug for single phase stuff. I always check the wiring inside the equipment before plugging it in the first time. Found a lot of poor work there before. The attitude is if it works and does not blow up it ships.

author: Kohanbash
author_rank: Regular Contributor
timestamp: January 05, 2014, 05:33:28 pm
content: Quote from: XOIIO on January 05, 2014, 05:23:49 pmThese are standard ways of wiring it is not someone who messed up.

author: smashedProton
author_rank: Frequent Contributor
timestamp: January 05, 2014, 08:16:45 pm
content: I once had a cap with a black band on it which was labeled positive.... they are usually negative on the band. Reguardless, the explosion made the rest of my day more exciting

author: SeanB
author_rank: Super Contributor
timestamp: January 05, 2014, 08:28:11 pm
content: Depends on how big the cap is. Was fun getting the 100uF 16V wet tantalum I wired in backwards out of the card frame when it went bang after around a minute of power up. No damage other than to my pride, and losing one of the precious stock of caps. Had to lift 2 cards out together as the case had joined them.

author: XOIIO
author_rank: Super Contributor
timestamp: January 06, 2014, 05:00:16 am
content: Quote from: SeanB on January 05, 2014, 08:28:11 pmouch.Well, Capacitor explosions are always fun

author: Dave
author_rank: Super Contributor
timestamp: January 06, 2014, 05:06:43 am
content: Quote from: sdk32285 on January 05, 2014, 02:08:59 pmI think you might have mixed it up a little. Brown and blue are commonly used for mains wiring (brown - live, blue - neutral).

author: amyk
author_rank: Super Contributor
timestamp: January 06, 2014, 08:37:33 am
content: When in doubt, get the DMM out...

author: Kohanbash
author_rank: Regular Contributor
timestamp: January 06, 2014, 03:51:12 pm
content: Quote from: Dave on January 06, 2014, 05:06:43 amI work in the DC world which is where I see PWR=brown and GND=blue or grey.I have no idea what is done in the world of AC.

author: Phaedrus
author_rank: Frequent Contributor
timestamp: January 06, 2014, 11:11:28 pm
content: I do ATX+12V = Yellow+5V = Red+3.3V = Orange+5VSB = Purple-12V = Blue-5V = WhitePS_ON = GreenPW_GD = GrayV_Sense = BrownGround = BlackOr, more realistically considering recent trends...:+12V = Black+5V = Black+3.3V = Black-12V = Black-5V = nothingPS_ON = BlackPW_GD = BlackV_Sense = BlackGround = Black

author: Monkeh
author_rank: Super Contributor
timestamp: January 06, 2014, 11:14:44 pm
content: Quote from: sdk32285 on January 06, 2014, 03:51:12 pmRed and black is the norm for the vast majority of the planet. I'd love to know where you are, so I can add you to the list with the US and their black and white conductors for AC.

author: Kohanbash
author_rank: Regular Contributor
timestamp: January 06, 2014, 11:57:14 pm
content: Here is my original postQuoteHere in the US most of what I do agrees that red is power and black is ground however a lot of items that I have gotten from Europe (power bricks, sensors, etc..) use brown for power and blue for GND. Attached is a snippet from a German laser scanner.There are actually some industries that have other standard colors. For example in agriculture (in many countries including the USA) a lot of the sensors use red for signal, white for power, and black for ground.

author: Unknown
author_rank: Unknown
timestamp: January 07, 2014, 05:03:55 am
content: Quote from: sdk32285 on January 06, 2014, 11:57:14 pmRandom low voltage bits of kit don't count. I think I have used every colour available for every function possible over the Years. There is no real standard for low voltage electronics.

author: hiddensoul
author_rank: Regular Contributor
timestamp: January 07, 2014, 11:10:19 am
content: I worked on a PLC system a while ago and every single wire was exactly the same, all bright red except for the Mains AC in to the power supply

author: Kohanbash
author_rank: Regular Contributor
timestamp: January 07, 2014, 01:21:42 pm
content: Quote from: Lurch on January 07, 2014, 05:03:55 amI have seen a enough items from Europe with the brown/blue that I would think it is more than random. That example I gave is from a large company that makes a lot of sensorshttp://www.sick.com/group/EN/home/Pages/Homepage1.aspxfor mostly industrial use.

author: SeanB
author_rank: Super Contributor
timestamp: January 07, 2014, 03:26:56 pm
content: Brown/blue is a harmonised colour use. A standard in the EU for power wiring. PLC units often are all the same colour inside, at work the one was originally brown, my addons are in red and some are in flexible mains cabling. Another from PRC is wired in blue, except for mains wiring which is either green or white. Another is all in black, some are numbered at the ends with a stamp in white but it wipes off at a look.

author: Unknown
author_rank: Unknown
timestamp: January 07, 2014, 05:18:58 pm
content: Wiring on a PLC would likely be down to EN 60204 which doesn't always care about polarity, just signal types/voltages.

author: hiddensoul
author_rank: Regular Contributor
timestamp: January 08, 2014, 03:07:27 pm
content: Quote from: Lurch on January 07, 2014, 05:18:58 pmThe one I worked on wouldn't be covered by the regs in EN 60204 as it was developed in house by an Australian company so they don't have to follow European standards and it was also 35 years old before EN 60204 was in force anyway.Here is a video of the conversion we preformed on the system giving us 1mm accuracy cuts of the logs up to 8.7 meters in length and 1.5 meters acrossThe white wiring in the enclosure is our new wiring as we kept our system separate so it can be reverted to the old system if needed in case of a problem with the MCU, this was due to it being an operational sawmill that couldnt afford downtime so we did the upgrade in stages of 4 weeks on roster days off