วีดีโอ

Thanks for this!👍

Why the metal case of transformer give different voltage? Isn’t metal a good conductor?

I also have this lab power supply it does not give any volts from amps already the potimeters are in order what else could be defective I have measured a lot of resistors that seem to be ok so far I can't find the defect

Along with electronics I find, fix, and sell small engine equipment. The same thing holds true. The bean counters get involved and the product gets cheapened up. Names like Cub Cadet, Troy-Bilt, Craftsman and many more. They all got bought up by MTD or are now made by MTD for them. They are told "build it to this price point." They all are cheaply made now. Plastic bushings, no bearings, Thin metal. Briggs & Stratton used to build world class engines...now they're Breaks & Scrap 'em. We've become a throw away society and no one knows how to do repairs or basic maintenance anymore. It stops running...they throw it away and get a new one. Actually this has been good for me...I've made some serious $ with my find, fix, sell side line. An, oh yeah, thanks for the video... well shot, clear and easy to follow!

I'm making a home NAS for my family and this is friggin awesome. Was eyeing this case and you helped me make my mind up. Fire!

How manu hdd i can fit in it, for nas.

May be the fan causing the ripple!

Thanks for this video!

LOL what a fool. All he had to do was clean the paint off the chassis where the transformer legs bolt so that all the transformer legs made good equally conductive contact to the chassis. But all he did was destroy the isolation of the chassis from the NEG terminal by making them no longer isolated. What a fool. You should never really connect the GRN to the Neg terminal on the front anyway. The ground terminal is there on front so you can connect it to whatever unit that is under test chassis, so that both the power supply and the unit under test have the same chassis ground. . Chassis GRN is where all the filtering caps dissipate the AC noise to. You should never connect it to NEG terminal.

From memory the safety earth/ground wire has to be rated such that 25A can be sustained for 1 minute without the wire fusing or getting unsafely hot.

Your assumption that there is a competent engineer looking at the overall design performance is very optimistic. In the USA with electronic instrumentation design, which would include a bench power supply, the modification would have the rear and front panel earth wires go to a single crimp eyelet, which would then be attached to the transformer grounding hardware (case hardware). The eyelet barrel size is chosen to accommodate both wires with a single crimp using an approved crimping tool. This way if the case connection (transformer case hardware) comes loose you will not lose your earth ground between the rear plug and the front connection. To put it another way all conveyed earth connections are always mechanically rigid without depending on screw hardware or a soldered connection. If a soldered connection gets hot it can come loose. So, the rear ground connection would be a crimped female crimp terminal (usually insulated) designed to fit the tab on the power inlet. Which would also be crimped with an approved crimper. For a complex ripple noise waveform many times it will be specified in RMS, which implies the measuring device be true RMS with a rather large crest factor and a large enough bandwidth. Many newer oscilloscopes do a very good job at mathematically calculating the RMS value of a complex waveform (with a large enough sample size). But, it can be worthwhile to get an FFT of the noise, and also in some cases THD.

I have bought a similar power supply, it used to make those clicks which I don't even know what they represent, and now it has stopped making those clicks when I raise the voltage, and it doesn't go above 15V even though it should go to 30V. Does anyone know what the problem is?

a 1x probe is NOT 20Mhz, it is more like 5MHz. ....you should have used 10x

Better to take all earth wires back to the earth socket or single fixing point, don't daisy chain them.

Well done

1. As you mention, that scope probe is not the best, and only because you're using a ~4" long ground connection. You need the spring on the ence of the scope probe, its about 1/2" long max. 2. 50Hz ripple is really a ground loop, or a really bad transformer. You should of tried w/o the earth ground and supply grounds tied together.

I never use AC coupling because I want to see the entire vdroop. I always use DC coupling so I can see everything. I see a lot of folks using AC coupling but..the data is limited

What if I don't have a face ground connection in my electrical installation? Does the video still work?

Management: "It's cheaper to just fire the engineers. Bonuses for management this year!"

"Shellshocked by the magnificent idiocy" "and they are already whackin eachother off" Now this is real literature

Did not have time and patience for that, just binned

It isn't a great idea to solder the ground wire, because if current starts flowing on it, it may desolder itself and let the human conduct the current instead. It should be crimped instead...

Cutting corners? Then why You are using that cheap soldering iron?

At this point I consider myself fortunate to be working for a business that doesn't have senior management Muntzing products for us.

Chinglish think star earthing is an American sci fi drama. You take a look inside an old Hameg class power supply from the 1990's, there are a billon more components, with electronics, morer is betterer.

Do you have links to your channels on library and bit chute?

Great work

I think it’s more likely that they had a warehouse full and discovered the issue, the solution as they saw it was to just remove the ground bar. Technically rubbish, but very pragmatic you have to admit.

If you draw one amp through a bridge rectifier, all things equal, it dissipates around 2.8 W. If that energy has nowhere to go but the ambient air the high temperature isn't surprising. Btw. it seems you haven't uploaded in over three years - why?

Ground star configuration for the win.

Single point grounding is a must.

Great fix. The source of noise was likely due to eddy currents flowing in the transformer laminations causing a ground loop via the ground wiring. Rule number zero: ground everything to a single point. Treat that point like Rome (that is, all roads lead to Rome). Any other arrangement is certain to introduce noise - you elegantly demonstrated that.

I can guarantee that there was no review meeting. The managers are nothing more than schedule-monkeys, there was no technical supervision, and the decision to connect the shorter wire was made by production. It is the new normal.

Good thing I prefer my supplies and measurement tools to float. Unexpected ground loops can be confusing or dangerous.

I had the same problem , nearly 45 years ago. Did build my oven transformer to a powersupplay when i was sin engineering class. Solution was to weld a seam over all the metal plates of the transformer. Connecting them solid together. Reduced the 50 Hz noise.

Haha, hilarious and great job repairing it. The really need to make sure the Asian kids are over 10 years old who work in the company and manufactiring line.😂👍

Funny how you blame the account managers rather than the engineers.... maybe you bad experience in your engineering career. For me it's usually both or a New Product Introduction team 😂

Why would you want to connect earth ground to the negative output terminal?

I think the main cause of the ground problem is the lamination of the transformer core and the paint on the chases

"How to fix your ground-ripple: This 1 easy trick that PSU-manufacturers do not want you to know!" a 10cents fix is kinda disgusting to see. If the bad ripple just reduced their sales by 0.01% than had cost them more money than the wire.

Well . That meeting was of course held in some 💩chinese language...🤷🏾

It's a disgusting shame that costumers have to fix brand NEW factory products because the companies became retarded greedy judes 😢

Great video, thanks.

simple add a capacitor to your output. problem solved. Go build a AC/DC full bridge rectifier regulator and you'd know its simple as that. 3 Farads does wonders for elimating ripple. (no I didnt typo that... yes 3 farads)

Isnt your oscilloscope also grounded? Doesnt that introduce further path of current flow, which needs be taken into consideration?

The design was OK but the implementation left a lot to be desired. I wonder if the even did any ripple measurements on the assembled product.

You should not have to fix new equipment. I like the large transformer. A very good fix but, too much work.

"Magnificent idiocy" - You got that right!

Great work. Almost like detective.

Close to reality... thanks to the video and explanation! By the way if the GND is connected to the Negative (COM) will in general add or cancel the noise ? We always connect those two together with a short cable right at the PowerSupply (Mean Well) terminals. I notice noise and want to get rid of it. Will try by removing that bridge.