EEVblog 1402 - Rohde & Schwarz NGA100 PSU Teardown + GIVEAWAY

Teardown of the new NGA100 100V 2A NGA142/NGA102 Lab Power Supply, and a look at a few issues found.
PLUS a GIVEAWAY of two units!

00:00 - First look
02:41 - Those connectors AGAIN
04:18 - Voiding the Warranty
14:25 - Playing around
22:27 - Noise measurement
24:09 - Current range overshoot!
28:11 - Another weird CC mode problem
33:57 - GIVEAWAY!

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#ElectronicsCreators #Giveaway #PSU

[loneoceans]

Pretty cool that there is no silkscreen but necessary designators and labels are directly in the soldermask and enig plated :)

[joaquins]

That's huuuge overshoot, with the 20V back to de CC mode, it might blow up quite a few loads...

[gabor-smith]

lmao "stingray", with that overshoot it makes it all the more hilarious

[drdiesel]

A transient analysis of various power supplies would make a great video. Not only on startup/shutdown but CC shorts and recovery while in process.

[Mtaalas]

About the output terminals... they can do way over 120V, so they absolutely shouldn't be used without shrouded banana plugs because you can accidentally touch bare contact and get a nasty shock. So those type of terminals are acceptable.

[debec]

Its a bit hidden in the manual but: "Long press on the Back key resets the channel history information."

[AmericanLocomotive]

The "X" notation is actually pretty common among other German manufacturers too. A lot of the CNC equipment I used to work on used Siemens controls. Siemens used the "X" prefix all over the place on various ports/connectors.

[baljotsingh]

I had this in cart for the past few days. Glad I didn't pull the trigger before you uploaded this video. That overshoot is nasty. Thank you!

[trevorvanbremen]

IMO, the BEST test of current limiting on a PSU is...
1: Set output voltage to the maximum it can produce (100V in this case)
2: Set the current limit to 20mA
3: Connect a 'garden variety' LED directly across the output
4: Enable the output

If you still have a working LED after that, then it's _possibly_ a decent device.
(I had to make HUGE changes on my own bench PSU in order to have LEDs survive this test even though it only goes up to 30V)

[iamdarkyoshi]

I blew up my homemade bench supply and haven't had a working one since, hopefully I can nail the giveaway! Back to the vid!

[wtmayhew]

I’m not sure about the intent here with the initial high speed fan; it could be lackadaisical engineering or R&S meant to do it. I used to work in a datacenter, and servers often have banks of multiple fans and two fan banks in series to allow for a fan failure in one bank. Anyway, the Dell servers we had sounded like a 747 jumbo jet for about five seconds when initially switched on. There would also be a puff of dust out of the back of the servers. The servers stayed pretty much spotless inside. I concluded that it was no accident that the fans were initialized at the highest speed - it was to blow out the dust. It also gives the auxiliary “lights-out-management” supervisory processor an opportunity to check the health of the fans to see if all fans can meet or exceed an acceptable RPM threshold.

[stevetobias]

Nice for a basic model. Like the toroidal transformer, looks like an audio quality transformer.
Good on you for the giveaway, I'm a member but won't enter because there are others who would need it more. Love that you're giving one away to a hacker space school. 👍

[jeffm]

Software driven CC is a bad idea IMO. Give me an old fashioned analog loop.

[aicisha]

19:44 that Pmax of 0.36W was recorded when you first pressed the output on button because the output capacitors were empty and they simply charged, right?

[OneBiOzZ]

The fan on full blast on start helps unstick fans

[blockbertus]

I assume they blast the fan at 100% on startup to blast out some dust.
Some OEM PCs do something similar.
Still annoying, though.

[kanetw_]

The 0.021A is probably a really quick spike in the measurement due to capacitance or such. Too fast to show up on the display but it's there.

[yiannisp]

About the current range overshoot, I use the r&s hmp4040 and did the same experiments a few months back. Sadly I observed the same thing during overcurrent conditions, the supply seems to reach the full voltage and needs 10-20 ms to start current control. Unfortunately that's not good enough with the GaN devices I am measuring. If the device is unstable, it usually can't handle the initial surge of current during that 10-20 ms and it destroyw itself ... I wonder why it is necessary to have that 10-20 ms, it doesn't seem needed in a classic analog constant current control loop like the one used in the μSupply...

[pnjunction]

Dave, could the overvoltage issue be a result of charging the output capacitor? Would be nice to see the actual current drawn by the load.

[stevenbliss]

Makes me wonder if their other equipment is similarly overprice mediocre stuff.