Inside a cheap eBay LED power supply. (With arcing flaw.)
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- čas přidán 14. 02. 2018
- This fairly common power supply has a very silly flaw involving the choice of assembly hardware. It also has what I would describe as just-acceptable separation of tracks with no anti-tracking slots.
These power supplies are the type normally seen lying loose in shop windows connected to badly installed LED tape and with their open live terminals perilously close to random metal junk in the vicinity and the aluminium window frame.
The hot diode issue is why I always recommend under-running these power supplies for a much longer lifespan.
If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and random gadgets for disassembly at:-
www.bigclive.com/coffee.htm
This also keeps the channel independent of CZcams's advertising algorithms allowing it to be a bit more dangerous and naughty. - Věda a technologie
PS: Instead of botching a heatsink on the chip they should have used a chip with a lower ON resistance. But such a chip is probably too expensive for super cheap ebay items...
As a neophyte hobbyist, I learn so much from your wonderful videos. There is a lot to be learned from dissecting small simple electronic "doo-hickeys" and you make it entertaining and easy to understand. Thanks for doing what you do, Clive!
I worked on a hi-pot tester for Sunbeam that put 1500 volts across blenders and other appliances to test for case insulation breakdown. Sharpest memory was of an engineer that couldn't understand why his O'scope couldn't handle a 1500 volt waveform. It was only rated to 1000 volts.
If someone needs a more scientific explanation, the 431 is a precision voltage reference, basically a programmable, more stable zener. The resistor divider is used to scale down the output voltage to 2.5V. The 431 leaks current to maintain a stable voltage and that current is used to control the led from inside the optocoupler. The capacitor is used for compensation, basically to slow down the reaction of the 431 so that it doesn't ring.
It's essentially a comparator and a 2.5V refrence in a single chip, which when used in a closed loop becomes an adjustable shunt regulator.
Yeah, what he said.
I saw your video last night about fixing a faulty remote control,and as the volume control on mine stopped functioning a while ago,I opened it all up,and found the contacts gunged up with some tacky glue which was preventing current passing through the connectors. I cleaned everything,even the case,and luckily it's now working fine. Thanks for the demonstration,very helpful.
Clive I continuously love your videos. I'm an electrical engineer and I learn a lot every time I watch you!
It must be ok though, it has a CE mark.
😆
China Export: siloscordoba.com/blog/corporate/china-export-is-not-ce-a-symbol-to-cause-confusion/ I never said they weren't clever...
"A logo very similar to CE marking has been alleged to stand for China Export because some Chinese manufacturers apply it to their products.[19] However, the European Commission says that this is a misconception. The matter was raised at the European Parliament in 2008.[20] The Commission responded that it was unaware of the existence of any "Chinese Export" mark and that, in its view, the incorrect application of the CE marking on products was unrelated to incorrect depictions of the symbol, although both practices took place. It had initiated the procedure to register CE marking as a Community collective trademark, and was in discussion with Chinese authorities to ensure compliance with European legislation.[21]" -Wikipedia
WineScrounger I'm sure Mr Junker has this, as he has everything, under complete control. I feel so safe!
Getting a CE certification doesn't really require any officials as long you have the required test equipment and you can produce the proper documents.
Your voice is like a "Listening test" voice actor from my english class, epic, simple, fine
I enjoy the detailed schematic breakdown. Some key ideas finally clicked for me this time. Thanks again for the good work
Glad you posted this! I just got one of these in the post a few days ago (3.2A version, but looks pretty much identical), and though I've had it open to look inside (obviously) I haven't gotten around to actually using it.
Looks like a nice simple supply clive, not much to fail really :-D.
Yep they goofed up with the screw, but thats minor and can be fixed.
No one gingerly pokes as well as Big Clive!
This reminds me of the too-long screw I found in a 200A/5V supply. It was shorting positive output bus bar to the case. It was not a problem in bench testing because our electronic load was floating. When it was installed, it wouldn't turn on because it was then both terminals were shorted to ground. The negative via the device wiring and the positive via the screw. The screw that belonged in that hole was just a couple of mm shorter than the 20 other case screws.
Thanks that you have tried to measure the Voltage-drop through the diode and explained why it didn't work, I did the same fail and couldn't figure out why until now
*_American wiring colors:_*
*Black* = Live: 60Hz, 120V RMS at 0º (phase)
*Red* = Live: 60Hz, 120V RMS at 180º (basically inverted with respect to black)
*White* = Neutral
*Green* = Earth
Black and red are the ends of the secondary coil of the transformer that feeds the whole house. Black to white or red to white will give 120V. Black to red will give 240V. 240V is reserved for certain appliances (usually high power stuff like electric ovens, air conditioning units and clothes driers.
Worth noting: The NEC specifies that GFCI breakers be installed on a per-outlet basis depending on what room the outlet is in. (instead of having them in the distribution panel in the basement). The rooms and areas where they are required are typically where water may be found nearby.
Hope that helps.
EU:
Blue = Neutral
Brown = L1
Black = L2
Grey = L3
Green-Yellow = earth
Though eg. a german house will have always 3 phases coming in, inside only one phase will be used besides connecting an oven or a big heater. It's recommended to use L1, L2 and L3 for different parts of the house (for load sharing/balancing all 3 phases), but the cables to the rooms must use just brown for the used phase, no matter if it was L1, L2 or L3. So all normal 3 wire cables will have brown, blue and green-yellow.
There are some more historical colors variations in Europe, so eg. blue _could_ also have been used as L2, in old houses you also may find green or red as L1 or anything that was available, so it's a good idea to first measure.. Colors like red and white should not be used at all for mains voltage and are normally low voltage signal wires or alike. But white, violet, orange or pink could be used as a phase in some countries (eg. for switching lamps), so anything besides black, brown, grey, blue and green-yellow is not really standard and not safe to touch..
Ooooh! Deutschland gets 3 phases in their residential wiring? That's really rare in the US.
Are those phases split up except for a few specific appliances? Does anyone use 3-phase DC power supplies for their computer?
US 3-phase usually uses Red, Black, and Blue for live; white for neutral; and green or green/yellow for earth/ground.
Technically you can mod any computer PSU to accept 3 phases by removing the PFC and replacing the diode bridge with a 6-diode rectifier.
I'm not sure why you would want to do it :)
Almost every house has 3 phases@230V into the distribution board. Each phase has to be secured by a RCD and you should use all 3 phases to balance the load on the 3 phases. Big loads (>2kW) like big motors or an electric stove will use all 3 phases (with a 5 lead wire), anything else will use one of the phases. A good practice is to use eg. L1 for light and L2 for the outlets of a room, so that a tripping RCD of L2 won't also turn out the lights. Ideally your electrical flow on the neutral is zero if you balance the load.
Technically you can mod anything to do anything else, but it's not usually practical. In the case of modding an entire new bridge rectifier, it depends entirely on what kind of filter and sense circuitry your PSU has. I'm not up to date with the latest and greatest, but for a while there, nice PSUs were getting more and more sophisticated.
As to why: Compare a fully rectified single phase waveform to a fully rectified 3 phase circuit. It takes FAR less filtering in the case of 3 phase to achieve the same amount of ripple.
*_RAMMING_*_ it right up to 'ya._
I believe I found my new notification tone.
I hope you actually went through with this
To add to the power confusion, US household power wiring is black for hot (usually two of them), white for neutral, and green for ground. UN electronics wiring typically uses black for ground. So if you grow up working on electronics and then do some DIY household wiring, there is a very good chance of getting the colors backward if someone hasn't told you how it works.
You can't measure the voltage drop of a diode in a circuit like this :). You have to use a scope. Without a scope, you have to take the diode out and try to apply the same DC current (but the actual voltage drop is slightly higher because normally in the circuit the current is pulsed).
I did consider these things, and it would take a scope to see a true indication of the voltage waveform. What would have been interesting is swapping the diode for a higher current one, or even a good quality fast recovery diode with the same rating.
Higher current diodes tend to have a bit lower voltage drop. But a Schottky diode could have also been used here. In the old days, Schottky diodes were only rated 30-60V. Given that the peak diode reverse voltage is several times higher than the output voltage, those Schottky diodes were used in 5V power supplies at most. Nowadays there are 100V or even 200V Schottky diodes and they can be used in 12V power supplies (or even 19V laptop ones).
Thanks Clive, this just alerts me to check that screw on my two new similar power supply units I have bought from China factory a month ago and haven’t started
connecting to two electronic projects yet.
I
What I read was that black for live came about from putting soot/carbon in the covering. In the original DC systems, return (-) was bare and then covered without soot. When it became feasible to use other colors and also with AC, some countries changed their color schemes but the US kept black as hot.
So much of the electrical system is about cost. Higher voltages in some countries because it required less copper to carry the same power.
I've seen that problem in the past with an APC switched power bar. A customer complained that the power all of a sudden went off when the power bar switched the top connection. Turned out one of the screws that was holding the bracket in place was too long, hence it got connected to live and created a dead short to earth. I think that was a bit of a design flaw...
"Didn't go bang"
awww - I wanted it to GO bang...
Make something go bang. Set the magic smoke free!
I wanted a bang 749 times larger than Hiroshima
In the USA color scheme, red is also live. It's used in circuits that require 240V - I.E. directly connected across both _live_ busses.
Red is also used for 3/4 way switches. Green/bare copper is ground.
Uh oh Clive, I just got a bunch of these exact power supplies..... thought they were not too bad aside from the soldered in fuse being too close to the metal casing. My screws were not overly long as yours. Installed a small piece of fish paper (electrical insulator paper) on the inside of the housing where the fuse is (and under the PCB) on all of them. Some electronic grade silicone to improve the isolation barrier. Plenty good now for for my application which is powering small test fixtures that have limited use. Chinese tend to overlook (not care) about these little details. But I have to admit they are otherwise well made and as long as the capacitors are decent, should last a very long time. A few that have long operating demand I upgraded to Panasonic EB capacitors.
Snip off any sharp pin ends on the HV fuse, the cap and the transformer. Seen lots of shorts to ground even with barriers as they slowly poke their way though them when they are sharp. Hard to be certain from the video but it seems the power supply is designed for 120vac rather than 240vac rating with the isolation gaps, especially with that earth mount flange across most of the HV LV gap.
+The Dollar Guy
Where do you get fish paper? I searched the internet for weeks before I had to give up
CodeBurger rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F122685440705
CodeBurger, sorry for the late reply. Looks like Agent Office got you taken care of. I purchased mine through ebay. They are in pre-cut sizes with adhesive backing. Awesome stuff. Ebay item 122685484714 for example is specifically what I used. Copy and past that number into the ebay search field and will take you directly to it.
ant thick plastic should do
Very appropriate cabling there for mains voltage ;)
Crude fuse ;)
4 days ago???
Fixture wires are sometimes size 16 even for high voltage cabling. NEC says fixture wire can be 16awg minimum here. Don't know if this. Counts as a fixture however.
The warm output diode will be more efficient at 90C - its forward voltage goes down as temp goes up. Certain modern ferrite transformer core materials have a 'sweet spot' of minimum losses at around 100C - cooling the core would reduce the efficiency. High temperature operation isn't inherently a bad thing - thermal cycling is the villain, causing repetitive expansion/contraction which eventually work-hardens the conductors, which then crack.
Interesting about the wire colours, I was working on the rear lights of US camper imported into UK and subsequently into Ireland and the person who had converted the lights (to insert an orange flasher and disabled the flashing of the red brake lights) had wired White as Live and Black to Earth and when I went investigating I found the live was Black - so the same colour issue with US cars as well - I thought I was mad but am glad to see you commented on the American Stuff being wired wrong
Surely the *screw* would become the conductor? So it would be on the thread area of the body.
I got the same 12V 2A LED power supply from ebay. The first one tripped a RCD and after that popped the internal fuse with a loud pop. I got a replacement that I have not yet put into
use. I have just changed the case screw at the back so it has more clearance from the heatsink.
@4:30 - 2,000 volts? you powering up enough LED lights to brighten up London at night?
Sir BigClive! Thank you for the video, I have to watch every one. I live in a large house and trying to go all LED, rather than the 55W bulbs that litter the place.. Looking at the worktop / sink area I'd like to put LED tape, are there any good drivers and perhaps a video how the drivers would be installed given the existing lighting is those fluorescent bars.. they have to go! There are some plugs but the toaster is in one of them.. Be well
Ollie B clive shall be knighted!
Siz banga if I become king he's first on the list 😁🙃😂
Odd that the input rating does not just state 85-240 VAC. Splitting the ratings implies to me that there is a selection that needs to be set inside. Would be interesting to see what it does with the low AC voltage input - might work?
You owe us a fuzzy pink Valentine's Day video/ artwork. Even Stewart mentioned you.
Stuart's awesome!
Black and red are both live in American wiring when using 120V split-phase to make 240V. (Also blue in three phrase.) Red is also used as the extra conductor for three-way light switches and such. But yes, white is neutral and green is ground.
OTOH, I use red and black for my low voltage power distribution, mostly 12V or 13.8V...
Clive, a slightly better diode you could use is an STPS10L60 ... it's rated for 600mV drop at 10A ... or around 400~500mV at 3A. (It varies depending on junction temperature - high junction temps, lower the Vf.)
The one on that PSU is, I'm guessing, an SB360 or similar type (Maybe an SB560 to make it slightly more efficient.).
Correct black in home is live and white is ground , in cars when American made red is live and black is natural ac is very clear and auto is very clear till they started the scam in 1977 with cars being no color code on high dollar car's , grey white seemed to be the worst on GM for no ref , just tell us to replace entire loom ! Game for sure !
black is live , white is neutral, and green is ground. (US electrician)
AC = Black is live, white is neutral, green/bare is ground, red is second circuit for a 12/3 or 14/3 configs for things like a ceiling fan with light. In DC systems, red is live, black is neutral, green is ground.
Not always true with American cars, they have MANY different color wires for live DC power delivery, because they need them, you don't want every single live wire being the same color, would be a huge PITA to trace faults.
In industrial control panels blue is DC positive, blue with white stripe is DC return.
yep , forgot common safety ground thanks !
Do I see broken traces in the feedback circuitry around 8:24 or its just an optical illusion?
Use an oscilloscope across that diode, Clive! Then you can calculate the dissipation. Thanks for the video of a potentially fatally-flawed power supply. A shorter screw, or even a nylon one, should be enough to make it safer.
RWBHere not so easy, probe ground is usually connected to earth, you cannot whack it in the middle of power supply circuit.
You need a differential probe or two channels and subtract one from another using scope math functions
Jan Hlavatý Secondary side should be isolated from mains earth, at least in theory unless I'm missing something. Or you can do it the ElectroBoom style and wrap your oscilloscope earth pin in tape.
That would measure the voltage drop. To measure power you would also need a current probe and a scope with math capability to multiply them. The simplest way to determine the power is to heat it with a DC supply until it reaches the same temperature as when it was in service.
Chris W - that's not a bad approach, but it doesn’t take into account switching transients which add to the heating.
As for the probe ground, there are a couple of ways of tackling that, the simplest being to temporarily disconnect the scope mains Earth lead. A capacitor on the probe ground connection is another option. Some older scopes also have the option to undo a link on the front panel, either with screw terminals or else a. switch. My (very old) scope can be used like that. Calculating the power from the diode voltage waveform can be done quite easily, if you apply the correct maths. No absolute need for a scope with all the bells and whistles.
P.S. - You could also unground the PSU mains supply, via an isolating transformer.
I like that power supply, despite its flaw, which can be corrected by a small modification. Might use one for a Raspberry Pi 3, for example, or for a 12V QRP transceiver, if the price is right.
Can I somewhere find a transformer winding ingormation for this exact PSU?
Hey Clive, can you maybe do a comparison of USB meters/testers?
The control chip appears to work similarly to the TNY279PN which just happens to be in the faulty Vodafone Sure signal (v3) I'm presently working on. Looks like the chip exploded and damaged the mains input cap, causing it to go short circuit and blow the PCB fuse! Just received the parts from Farnell, but it was a bugger to get a sufficiently short (due to compact design) 22uF 400v cap!
Here where I live code allows red wiring between the light switch and the fixture, and/or between 3-way switches. Makes it easier to identify which wire goes where when working on a switch.
Dear Clive,
The orange capped box you use to connect mains to your testing 'subjects', is that for sale somewhere, or is it a BigClive-original?
Cliff quicktest. A common workshop item here.
czcams.com/video/_DTmL73th7Y/video.html
Thanks!
You could use your scope for measuring the voltage across the diode.
Even with a scope it can be hard to get the forward voltage.
The voltage on the diode with the primary side on is about 24V.
The forward voltage happens for only about 1uS.
You are trying to measure good to about 0.1V.
That needs a really well compensated probe and a wide bandwidth scope.
One part in 240 is asking a lot.
In the US black is live in AC, but negative in DC. with 220v AC black and red are live 110v legs that add up to 220v.
Black and red are live, 120V RMS, and 180º out of phase with each other (A.K.A. inverted)
Clive
It has the European CE to Chinese Export mark so it should be safe Ho Ho.
Use to visit an large switch mode power supply manufacturer in the South West for two diffrent standards company's.
The quality manager fully tested all rebaged power supplies and their own to check they met either IT or other standard, usually international ISO/EN.
You would have had a field day there.
The dielectric test's on amps was intresting especially when they failed, reminded me of ElectroBoom.
There approvals lab had 4 permanent staff, he would sign/pass anything unless it passed all tests, not the CE one.
It now is part of a large Japanese coperation.
If the products do not meet the standards, main one is crepages and clearance between mains and secondary circuits and earrthing ect you should send it to your local Trading Standards.
As some one is going to be or has been hurt, killed or have a fire or both.
Thanks for your very technical and entertaining videos, love your cap.
Fun is mounting it, as the one screw is fine, as it hits board only, but the other grinds into the one side of the rectified Ac mains. Nice big skid mark when that finally arcs through the solder resist and flashes over.
The heatsink on the power switch is nasty, so it is likely that the failure will be flash over to the heatsink from the drain pins first, then the heatsink can flash over to the case.
2 output caps is more for cost reasons, the 2 smaller caps are cheaper than the comparable big one, as the small ones are more common in volume, and thus cheaper when you buy a million or so of them, even if you need 2. Plus you can cost reduce later on and simply remove one from assembly. No need to have extra caps on hand, if running short in assembly just leave the one out.
The 431 is a programmable zener / current shunt which is very stable with temperature changes.
I'm a subscriber from the US!
+bigclivedotcom I can confirm that in the US split phase colors are black or red for hot; white for neutral; and green for earthed. Transformers here have multiple taps to produce 110-120VAC that is delivered to residential customers.
May I please ask you about the English word for the safety switch you are touching with your left hand at 0:35, do you know where to buy one?
Cliff Quicktest.
I always wondering, could you use mosfet instead of that big diode?
Yes, it is commonly done.
It is called synchronous rectification. A tricky extra circuit pulses the gate of the MOSFET on while the conduction happens. It costs perhaps $0.10 more to make one like that.
are the output terminals and consequently the load floating at ~120V AC above ground?
Richard No, output is isolated by transformer and optoisolator. There may be a small leak through the Y cap because it didn't go to actual ground.
it's odd how some of your videos are on the center/sub channels of my 5.1 but most other videos are on left and right. neat
edit: i only noticed this when some of your videos go silent because i have my speakers mirror left and right to the other speakers. it ignores rear and center/sub channels. so the audio goes silent.
I'm ordering a load of these so I can give my house that "Tron" lighting theme.
Is it possible at all to pass emission without a CM choke?
What magnifying glass are you using?
A common ebay illuminated magnifier from China.
Hi Clive, notwithstanding your tests and demonstrations in this video, are these format of power supplies safe given it looks like the connections are exposed? Or at the screws insulated from connectors? If the screws are not insulated and live, how can one make this form of power supply safer?
These chassis supplies are intended for use in electrical enclosures. Unfortunately I see a lot of them dangling on flex with exposed connections.
@@bigclivedotcom Enclosures it is then. Thanks for coming back to me. Always a fan of your videos.
If this is for an application exposed to public touch I strongly recommend buying compliant supplies from a reputable component supplier.
@@bigclivedotcom Thank you Clive.
first time asking a question in here..
If the led in the opto isolator is defective, the device is going to release the magic smoke?
could they not design the schèma that if a sensing component fails it just stops working?
Opto isolator failure is very rare. But if it did then the voltage could go up to the unregulated threshold.
You need some kind of electronic load for higher power/voltages.
The mounting screw stand-off that attaches the Earth to the case looks like it would be very close to shorting to the Neutral and 0v tracks.
bigclivedotcom But the live pcb tracks have limited clearance horizontally to the case unless there is insulation all around the pcb edges. 3mm I believe from live to earth. Also the earthing connector should be separate from any mechanical fixings to meet current safety standards.
The best way to test the voltage on diode 19:00 is to use an oscilloscope. And see the constant and variable component.
Can you explain how a charge pump works? I've looked it up and I still don't get it. I get what it's for but don't understand how it works. How does it create a negative voltage froma positive line?
Take a capacitor and charge it up from +12V.
Now disconnect it and hook the positive end of the capacitor to the "ground"
What voltage will be on the negative end of the capacitor at this point?
Connect the negative end to the load side briefly
Repeat a lot of times per second.
The color coding here for single phase is generally black is live and white is neutral on a 120V line and black and red is 240, both considered to be live.
red can also be used for a 3 way switch where the red is the link between the switches.
and green is ground
I didn't mention that because it's effectively the same in the UK lol. Green vs Green/Yellow. Close enough to the same to not necessarily be noteworthy I suppose.
I was waiting for your exclamation over the diode voltage drop.
Where did you get that pedal looking test box for introducing live mains? Or what is it called? Iv'e never seen one and it looks handy.
Search his channel for "quicktest" and it'll show up.
Nah its a quicktest. Clive's definition of a "deathdapter" is one of those cheap chinese plug converters, usually containing no earth pin, or one that is not connected; and multiple ways to accidentally contact live mains. :)
We got this, its a quick test, avaliable in uk and us colours, there are copy ones from cpc, its not an expensive tool. And is very handy.
Ed Gein, when you lift the lid on a Quicktest, the power to the output is automatically switched off. The Quicktest is quite an old idea. They were around in the early 1970's, maybe earlier. My first electronics job design workshop had several old ones in 1975,. They were supplied by Radiospares (now RS), and others.
AKA "SafeBloc" (the original, SOLID ones were):
flic.kr/p/21CAcwu
In most slavic countries old colour code was black for live blue for neutral and there is no earthing.Three phase on other hand varies a bit but in my country it is red green yelow in circuits with bus bars and for cables it is black brown and grey.Blue is neutral and ground combined.
Кристиян Митев IEC says blue is neutral green/yellow striped is earth and combo is all 3 colors or blue with green/yellow tape at ends and visible spots or green/yellow with blue tape.
I don't know who should i ask, but what's the thing called from which he takes power from,i mean the circuit thingy with the live,neutral and ground which works only when closed?
Gogu Mihail , CPC Farnell sell one called a Quicktest
Early ones were called 'safeblock' in the UK, the more modern ones were called 'Keynector'. This one looks just like the Keynector.
I have seen many of your presentations so I think you missed something the chassis mounting screw was the correct length so it could contact the heat sink increasing its effect size by using chassis too
The heatsink was live.
What is the max frequency of HER208 rectifiers
A scope on the diode would be interesting
Red and black are the colors used in U.S. also for 240volts. And, black is line and white is neutral for 120volts.
I’m not really into wire stuff but it’s nice to see you open up shit
Thanks for another great video Clive, made me wonder if anyone else would be interested to see a video comparing constant voltage vs constant current LED power supplies along with how to find the right supply values for LED tapes? Cheers
THE LED tapes need constant voltage supplies. The current varies from brand to brand so only a proper test on a bench supply will show the true current. Then double that to get a power supply that runs cool.
bigclivedotcom cheers Clive, makes sense - I guess a constant current driver could easily deliver too much energy and kill the LEDs..... I wonder what would a coiled reel of overdriven LEDs look like at their point of doom :=)...... flir time-lapse time?
Where did you get this nice mains-clamp ? This would be very handy some times.
The connector unit is a Cliff Quicktest.
thank you
Why did the arc not trip your RCD?
I had one of those go bang on me, the legs of the 470uf smoothing cap went thru the isolation in the case
I nearly burnt my place down forgetting about a cheap Chinese water heating element with zero cut off or thermostat, hope everyone's proud of me. It boiled away huge pan of water then started melting and was on fire when I got back to it! Genius!
Clive., do you have a video where you explained where you learned all of the electronics part of your channel? Like circuits, understanding electronics etc. Can you maybe point me in the right direction to learn from home? Books/Videos/Anythin. Cheers!
I've picked the knowledge up gradually over my life. The way to access the information is different and easier now with the Internet. Find some sites and channels you click with.
In Germany a few (and some more) years ago, i think this was in the 60ies we had red colored wires as earth connection in house wirings which was often confused with live... making some plugged-in devices very ... interesting .... also in cables with more than 1 wires, the red one was sometimes a switched live connection or L2 in 3-phase cables... which was a really reasonable decision ;-)
The awkward thing is I have a power supply which looks _exactly_ like this, in fact I'm sure it's the exact model. Mine hasn't arced though. I replaced it with a different supply with a battery backup months ago.
How could they not catch that in design or at assembly?
Awesome video
Did you contact the seller and warn them of the danger of the product they are selling?
at least you used the right wire colors for hot and neutral :)
Curious - what caused the heat sink to become live? It shouldn't have been affixed to any live components, just the ceramic body of the controller. Maybe I missed it? I'm definitely guilty of that occasionally lol
It was anchored to the PCB with soldered connections to the negative rail.
Laziness in the way they routed the circuit, so it was soldered to power rail copper instead of ground.
Stinky Cheese No ground on PCB except the short strip to connect the wire to the chassis.
Yep, Black or red is live and white is neutral. Though I do like the method for remembering that Brown is live in the UK, because thats what color your pants will turn if you forget.
Looks a bit screwy to me 🤣
Buh Dum, Kssssssss
I'd be curious about how much current goes back though the diode when the voltage reverses. Standard diodes at 50/60 Hz isn't a problem, but you get up into KHz range and the diode doesn't shut off that fast. You have to use a fast recovery job, but I think even they have some issues switching off. A simple circuit with a variable frequency signal generator as supply, a load resistor and a scope on the output would make a good video. Either that or use a "sense" resistor between the diode and the filter cap and scope the voltage developed across it.
Schottky diodes have very little reverse current. There is no carrier storage so it is almost entirely the capacitance of the device that does it.
Congratz on 333K lol
They sell a power connector for LED strips much like a laptop brick. Not an expert but but the AC mains wire is very cheap and can pull away from the insulation exposing the live wires.
I don't think LED strips are bad,per se, but there is no provision for fuses. I put them under the cabinet but opted for a one amp fuse at the power source. I've seen videos how these things can get so hot, so very quickly and the power supply doesn't recognize a fault.
The steel is electrolytically galvanised and the the surface is phosphate treated to provide an 'anti-fingerprint' effect. It's not at all reliable therefore for a connection unlike British Steel's *Zintec*(tm) which provides an excellent conductive surface. In Asia they seem to be really keen on the phosphated stuff which is a pig if you want a decent chassis earth.
Thanks for sharing 😀👍
Where 's auxiliary winding for powering VIPER? Why I cant see it. Powering with internal current source would surely cause thermal protection activation quickly
mtmsweb It seems to be powered from part of the waveform across the switching transistor.
✌ *_"Heatsink"_* ✌ : a folded up cupboard fixing.
Clive: _"I'm liking this earth terminal..."_ - *I SHOULD HOPE YOU ARE - IT HAS POTENTIALLY SAVED YOUR LIFE!* :D
Which baboon was in charge of choosing the screws? Wow... that's.... erm... silly.
Clive, did you know that the reason POTS telephone line (or "battery" voltage, as it is known) voltage is +/- 48VDC is so that the high potential can overcome and breakdown poor connections and corroded joints, and allow the voice conduit carrier (the +/- 48VDC) to keep the signal flowing from exchange to CPE (Customer Premises Equipment - these are UK terminologies)?
My point is this - if +/- *50VDC* can arc and bypass corroded joints/high resistance joints, then 240VAC *WILL DEFINITELY* jump across this negligible barrier of... say, what - a few MICRONS or less (I know you know all this, it's for the benefit of the viewers/commenters) - learnt this stuff back in the 90s.
Nah, he wouldnt have gotten shocked if the ground connection had failed because he wasnt grounded himself.
lol, while watching this I spilt about half a bottle of alcohol on my desk and me while my gas-powered soldering iron was on. Thank goodness I punted away the bottle of butane away before it blew and set me on fire... until I looked down and noticed I was on fire. .. at least I don't have to shave anymore...
Oh shit it's the motherfucking Furher
Sketchy O shit, waddup? Another adoring fan?
And he's on fire!
And here's a picture? ( yeh, yeh, it grew back. ) 😁
Is there a reason there’s no safety caps or varistor other than budget?
Just economy.
A Fast Max function on that DMM might have done the trick on the output diode.
most of these cheap power supplies you will find online that Majority of the ones on reviews, have "IT CAUGHT FIRE" type of review...... i purchased 2 300w 36v ones for a led bar. one immediately exploaded. and the other turned on but started smoking , i found that the ground wire, was touching the live Rail in the pcb . cheap power supplies for LEds' are built with living on the edge in mind .