Author Topic: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza  (Read 7031 times)

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Online Fungus

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #25 on: January 27, 2019, 10:33:53 pm »
Can anyone confirm if these have a massive output capacitor

You could try watching the teardown video.  :popcorn:

Short version: No, there's hardly any capacitance on the output at all.
 

Online Fungus

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #26 on: January 27, 2019, 10:36:47 pm »
I would of expected to see a rubber cap on the toroidal even before Dave rasied the issue, it was that obvious.

Definitely a fail, something that R&S should be looking into after Dave's "QC inspection".

Fortunately Dave did a whole segment on it in the teardown video, I'm sure R&S will see it.

Maybe Dave will get another one in the post in the next couple of weeks, at which point the only reasonable thing to do is to send me the defective one (along with an old couch foot)
« Last Edit: January 27, 2019, 10:53:36 pm by Fungus »
 

Online maginnovision

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #27 on: January 27, 2019, 10:57:37 pm »
I put this on youtube but... The case there is powder coated. Unless someone deliberately removes the coating and puts a heavy object there it's a non issue. Since someone would have to remove the coating it would also not be their fault, that's a VERY durable coating.
 
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Offline IanMacdonald

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #28 on: January 27, 2019, 11:49:26 pm »
You can can set current limit to say 0.01A and output voltage to 25V, repeatedly short the PSU output and do spot welding! Some PSU's have huge i.e. >680uF output caps that make CC mode kind of a joke.
That will be the main reason for the postregulator. Without it you'd need a pi filter with a couple of honkin' great caps to get the ripple low enough for a lab spec. That and the postreg can cut the current quickly in a s/c condition, which a buck converter cannot because of the stored energy in the inductor.

BTW if if output reverse polarity protection diodes are used, I'd like to see a polyswitch or fuse as well.  Otherwise an accidental reverse current into the output terminals could damage the wiring or PCB. People do sometimes use bench PSUs to charge batteries... and sometimes they get them the wrong way round.
 

Offline Wolfgang

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #29 on: January 28, 2019, 12:11:42 am »
You can can set current limit to say 0.01A and output voltage to 25V, repeatedly short the PSU output and do spot welding! Some PSU's have huge i.e. >680uF output caps that make CC mode kind of a joke.
That will be the main reason for the postregulator. Without it you'd need a pi filter with a couple of honkin' great caps to get the ripple low enough for a lab spec. That and the postreg can cut the current quickly in a s/c condition, which a buck converter cannot because of the stored energy in the inductor.

BTW if if output reverse polarity protection diodes are used, I'd like to see a polyswitch or fuse as well.  Otherwise an accidental reverse current into the output terminals could damage the wiring or PCB. People do sometimes use bench PSUs to charge batteries... and sometimes they get them the wrong way round.

... but the price for a switching postregulator is broadband PARD at the output. In this case R&S specifies 1.5mV RMS from 20Hz to 20MHz,
a RIGOL DP832 has 350uV RMS over the same frequency range. For sensitive RF or analog stuff the R&S noise level could be a bit high.
 

Offline splin

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #30 on: January 28, 2019, 12:30:44 am »
At 23 minutes I think you mean "convection", not "radiation". If heat is radiating out of the holes in the case then you've got a big problem.  :scared:

Nah, just means it's a rebranded Weller design.
 

Offline LapTop006

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #31 on: January 28, 2019, 02:13:38 am »
I'm a bit puzzled about their architectural choice of the big-ass, custom-wound mains transformer and a buck preregulator afterwards.

Why didn't they use a common flyback or forward regulator directly from mains as preregulator for each channel? That way they wouldn't need the big and probably expensive transformer but still had individual isolated channels with preregulation. The transformers for a flyback or forward can be much smaller and thus cheaper because of the higher frequency.

Possibly simply to give it the feel of a linear, comfort for those of us who still go looking for linear bench supplies.

I put this on youtube but... The case there is powder coated. Unless someone deliberately removes the coating and puts a heavy object there it's a non issue. Since someone would have to remove the coating it would also not be their fault, that's a VERY durable coating.

If you do have something heavy enough to rub on it (which is probably harder than Dave's demo since the case wasn't fully together), plus some vibration, it wouldn't last all that long.
 

Online Fungus

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #32 on: January 28, 2019, 02:26:42 am »
I put this on youtube but... The case there is powder coated. Unless someone deliberately removes the coating and puts a heavy object there it's a non issue. Since someone would have to remove the coating it would also not be their fault, that's a VERY durable coating.

I smell a challenge!  :popcorn:

That bolt looks quite sharp to me, I wouldn't like to rely on the powder coating for long-term safety.

« Last Edit: January 28, 2019, 02:29:45 am by Fungus »
 

Offline Dundarave

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #33 on: January 28, 2019, 03:33:50 am »
I put this on youtube but... The case there is powder coated. Unless someone deliberately removes the coating and puts a heavy object there it's a non issue. Since someone would have to remove the coating it would also not be their fault, that's a VERY durable coating.

When I viewed the video, I was hoping Dave would have had a quick peek inside the case to see if R&S had perhaps stuck a bit of insulating material to the inside of the case above the bolt end...  A square inch of adhesive insulator would do the trick.
 

Offline RoGeorge

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #34 on: January 28, 2019, 04:14:30 pm »
For a linear power supply, I was expecting to see 50/60Hz rectifiers and huge filtering capacitors near the big toroidal mains transformer.

If the ones in the video are linear power supplies, how come each channel have a ferrite donut transformer?  Wouldn't that turn them into switching power supply?  And, if we use high frequency anyway for the smaller ferrite transformers, why bother with the huge toroidal mains transformer anyway, what am I missing?

Offline stranger

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #35 on: January 28, 2019, 08:26:06 pm »
As said earlier I prefer binding posts on PSU, sometimes there has to be more than one wire to a terminal and stacked plugs are a poor solution. The bit that is surprising is the lack of grounding provision on the front panel. If developing some PCA that has been designed for star earthing back at the PSU it helps a lot if there is provision on a lab test psu that the appropriate terminals can be earthed at the psu to mimic the ground distribution of the final product.

At the moment I'm using Agilent PSUs and really miss not having a keypad to set demands but at least I can ground appropriate terminals at the PSU using the ground binding post.
 

Online Mr. Scram

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #36 on: January 28, 2019, 08:32:07 pm »
For a linear power supply, I was expecting to see 50/60Hz rectifiers and huge filtering capacitors near the big toroidal mains transformer.

If the ones in the video are linear power supplies, how come each channel have a ferrite donut transformer?  Wouldn't that turn them into switching power supply?  And, if we use high frequency anyway for the smaller ferrite transformers, why bother with the huge toroidal mains transformer anyway, what am I missing?
I think they're hybrids with switching preregulation, but I stand to be corrected.
 

Offline 0xdeadbeef

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #37 on: January 28, 2019, 08:41:45 pm »
The HMP device etc. are linear supplies, the HMC and NGE devices are hybrids. The teardown video shows three different devices, first an HMP2020, than an NGE100, than a HMP4040. At least I recall this order, maybe I'm mistaken.
Trying is the first step towards failure - Homer J. Simpson
 

Offline Wolfgang

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #38 on: January 28, 2019, 08:43:01 pm »
... what would point to some sort of switching regulator is the relatively high broadband noise level. Not sure either, there is no schematics available, I suppose.
 

Offline splin

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #39 on: January 29, 2019, 02:49:01 am »
... what would point to some sort of switching regulator is the relatively high broadband noise level. Not sure either, there is no schematics available, I suppose.

Or the bits in the teardown video where he points out the switching pre-regulator ICs and shows the datasheets?

For those interested, the HMP2020 & HMP4040 (at least - the NGE100 may be completely different but Dave didn't show any close-ups of the control logic) have two MCP3421 18 bit ADCs (6 pin devices marked CAxx and CGxx @ 5:37), presumably for the voltage and current readback. At around $.50 a piece they're sparing no expense on these moderately priced PSUs.  >:D They are good enough to meet the specs but they could have done much better given the high price point. I guess it leaves room in the line-up for the high precision/speed, uber expensive, PSU variants should they decide there is enough demand.

A REF5020 can also be seen which looks to be the 3ppm 'I' version. The ADCs don't have a ref i/p so I guess it's used for the set voltage and current. Anybody spotted the DACs?

[EDIT] corrected MCP342 typo
« Last Edit: January 29, 2019, 05:27:44 pm by splin »
 

Offline onlyrgu

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #40 on: January 29, 2019, 03:43:42 pm »
There is an Wifi Card installed (ie. You paid for the hardware) , but you need to buy a license  to activate it.
Their BOM cost goes lower if they sell the Supply without the (off the shelf)card?
Or is easier just make a single DFM for the supply?
Or can the make up the cost if the sell wifi sw / activation code separately to 50% of their consumers.
These questions are going to make me up tonight!!
 

Online Mr. Scram

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #41 on: January 29, 2019, 04:02:50 pm »
There is an Wifi Card installed (ie. You paid for the hardware) , but you need to buy a license  to activate it.
Their BOM cost goes lower if they sell the Supply without the (off the shelf)card?
Or is easier just make a single DFM for the supply?
Or can the make up the cost if the sell wifi sw / activation code separately to 50% of their consumers.
These questions are going to make me up tonight!!
Some would argue that everyone gets the upgraded hardware for a lower price, because a few people pay extra. By having some people pay for the add-ons, the final price for the cheap model can be lower. Its a somewhat complicated affair which isn't as black and white as it initially seems.
 

Offline ali_asadzadeh

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #42 on: January 29, 2019, 04:41:26 pm »
Dave That was great :-+ :-+ :-+

Please make some video on how the sense lines work?
You can order parts from www.ASiDesigner.com
we are a wire-based company
 

Offline onlyrgu

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #43 on: January 30, 2019, 09:18:49 am »
There is an Wifi Card installed (ie. You paid for the hardware) , but you need to buy a license  to activate it.
Their BOM cost goes lower if they sell the Supply without the (off the shelf)card?
Or is easier just make a single DFM for the supply?
Or can the make up the cost if the sell wifi sw / activation code separately to 50% of their consumers.
These questions are going to make me up tonight!!
Some would argue that everyone gets the upgraded hardware for a lower price, because a few people pay extra. By having some people pay for the add-ons, the final price for the cheap model can be lower. Its a somewhat complicated affair which isn't as black and white as it initially seems.

Sending a technician or engineer to upgrade the hardware is significantly more than the BOM cost. So sending a software upgrade code via email or post is way cheaper. Only logic explanation I can think of!

 

Offline Radiosonde

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #44 on: April 02, 2019, 12:04:19 pm »


I don't know what it is about R&S equipment, but the slightly understated and fairly German design always appeals to me in ways I can't quite explain. Nothing flashy or attention grabbing, just a measured "Want to get work done? Let's get going".

Yeah..thats really fascinating, but it isnt true on all there instruments today, some things are just to futuristic.
The golden age of Rohde & Schwarz design was about 1990-2004 or so ..back then there design was absolutely top.
Furthermore most of the used equipment comes from this era, they build alot of extremely nice stuff back then:
SMIQ,CMU,EB200,EK890,SMT,SME,FSEx,ZVx.....
you see I am crazy.:)


Gesendet von meinem SM-J730F mit Tapatalk

 

Offline pa3weg

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #45 on: May 23, 2019, 04:04:39 pm »
Right! So after some time owning these PSUs (10 pcs), I have one with a fault now. Real life teardown and repair happening.
One of the channels has no output, and the input fuse on the regulator module has blown, the rectifier measures short in-circuit. Next step is taking the rectifier out and checking the pre-regulator

Service wise the fixed wiring is a bit annoying, whole front panel needs to come off and  the outputs desoldered to remove the module PCB...
 

Offline KoF

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Re: EEVblog #1173 - Rohde & Schwarz Power Supply Bonanza
« Reply #46 on: August 08, 2019, 06:58:03 am »
Did you manage to fix it? - I also have a nearly totally destroyed HMP2030 on the table.  :rant:

The first channel controls the soft start of the transformer and the fan. But if the first channel is broken, what do you think will happen?
Right! |O  The relay does not switch and the resistor to be bypassed burns. At the same time the other channels die a heat death because the fan is not running. :palm:

At two channels, one out of two large 2200μF capacitors were exhausted and had almost no residual capacity. - But these are not brand parts ...
In one channel, the transistors of the pre-regulator had burned out and in another, the linear post-regulator transistor was destroyed.

So far, I've spent nearly 10 hours finding all the problems  :horse: - two of them just went for disassembly and desoldering.
Without a service manual, this is really a tough job. :-// Does anyone have a service manual for the HMP series?

By the Way... the DAC on the Board is an DAC8552 (MSOP8 Marking D82) from TI. Dual Channel 16Bit with SPI
Failure Is Always An Option 
 


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