Products > Test Equipment

Rigol MSO5000 Power Supply

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beatman:
i disagree.companies cut cost everywhere.see the prices from capxone samwa samxon etc.i do repare and i own mainly a lot stuf audio amps processors etc you can see inside of 3-4000 euros device the cheapest crap.this is unacceptable.in most cases 85C temp. all the time found on psu's (any kind of psu's) audio household pc's no more than 7 to 10 years old this crap deformed or leaked.never sean good brand capacitor goes bad that way.i do a lot measurement before and after replace (crap)acitors in relative new devices in most cases the ripple and noise get a lot better.

2N3055:

--- Quote from: beatman on July 09, 2023, 08:34:26 am ---i disagree.companies cut cost everywhere.see the prices from capxone samwa samxon etc.i do repare and i own mainly a lot stuf audio amps processors etc you can see inside of 3-4000 euros device the cheapest crap.this is unacceptable.in most cases 85C temp. all the time found on psu's (any kind of psu's) audio household pc's no more than 7 to 10 years old this crap deformed or leaked.never sean good brand capacitor goes bad that way.i do a lot measurement before and after replace (crap)acitors in relative new devices in most cases the ripple and noise get a lot better.

--- End quote ---

That is why you took out capacitors that are rated for 105°C? Because some random PCs had bad 85° capacitors 10 years ago?

Also, this power supply is basically a preregulator. Board has dozens of local regulators that are critical to signal integrity. If anything, those should be made "better". But to do so would need some real engineering, probably a respin of mainboard and would also be a point of diminishing returns, because other types of signal integrity problems would influence signal more (ground paths, crosstalk, shielding..)...
And then you have noisy front-end/ADC on MSO5000 that drowns any other interference in it's own noise floor..

It is basically a audio-foolery type of nonsense. Let's change all the capacitors for most expensive ones because "the more - the betterrer"  ((c)AvE)..

Let's see measurements before and after. Then we can see if it was worth it. So many of poor souls that do not have enough knowledge can realize it was a bad idea to disassemble perfectly working instrument (with maybe warranty) and possibly even damage it (Murphy never, ever, sleeps) to gain absolutely nothing. Except hand waving and woodo.

Or maybe it is not woodo. Maybe it was worth doing it. Easy to settle: lets see what oscilloscope measurements got better as opposed to original PSU. Hard numbers. Like: RMS and P-P  noise on 4mV/div was xx RMS and xx P-P and now is 1 or 10% better.  Or in FFT you can see that spurs at xx MHz are xx dB down ... Those kinds of things.

Or maybe statistical analysis of MTBF and defect rate on these PSU based on full battery of thermal tests in environmental chamber of say sample of 100 ?

Here's one data point for you: there are literally 10s of thousands of those sold and there has been few years now. Not to mention all kinds of similar PSU designs by same manufacturers for other scopes... And you know what ? There has been practically ZERO defects on PSU for reason you stated. 
Oh, there were (expensive) Keysight scopes with PSU problem, but even those were not because of capacitors...

Or only metric that it got better is  that now you "experience the clarity of waveform presentation with nice and crisp peaks but subdued curvature of low frequency spectra and better defined pixel presentation of fine details..."

Protegimus:
Now that experts have joined the conversation it seems like a good time to post before and after measurements.
I was actually waiting until I'd completed the operation to make a better assessment (waiting on replacement Panasonic 470uF 16V capacitors), nevertheless ...

PVP2350 probe grounded to the scope calibrate ground
before - MSO5000_OEM noise 1mV 1ms 20MHz_filter screenshot

after partial replacement -
MSO5000_partial noise 1mV 1ms 20MHz_filter ave 4

be aware firmware was 00.01.03.02.02 at the time of original measurement, current is 00.01.03.03.00.

With regard to the comment about, "Thinking they know better than designers". Little ironic considering they make money plying their wares from the forum EEVBlog which is based around Dave's critique of equipment design and implementation.
Pretty sure you don't have to look too far in the teardown videos to find comment on use of low quality components...

In terms of the PSU being a pre-regulator and that there is additional regulation down the line. Well that may well be so, but regulators regulate, it is the filter components that reduce noise.
Reducing noise at source in the dominant switched mode power supply source will provide benefit which is all we are addressing here.

Gents, if you can't add anything in terms of engineering or recommendations, don't post your emotive responses to trash this thread - make your own.

2N3055:

--- Quote from: Protegimus on July 09, 2023, 10:44:04 am ---Now that experts have joined the conversation it seems like a good time to post before and after measurements.
I was actually waiting until I'd completed the operation to make a better assessment (waiting on replacement Panasonic 470uF 16V capacitors), nevertheless ...

PVP2350 probe grounded to the scope calibrate ground
before - MSO5000_OEM noise 1mV 1ms 20MHz_filter screenshot

after partial replacement -
MSO5000_partial noise 1mV 1ms 20MHz_filter ave 4

be aware firmware was 00.01.03.02.02 at the time of original measurement, current is 00.01.03.03.00.

With regard to the comment about, "Thinking they know better than designers". Little ironic considering they make money plying their wares from the forum EEVBlog which is based around Dave's critique of equipment design and implementation.
Pretty sure you don't have to look too far in the teardown videos to find comment on use of low quality components...

In terms of the PSU being a pre-regulator and that there is additional regulation down the line. Well that may well be so, but regulators regulate, it is the filter components that reduce noise.
Reducing noise at source in the dominant switched mode power supply source will provide benefit which is all we are addressing here.

Gents, if you can't add anything in terms of engineering or recommendations, don't post your emotive responses to trash this thread - make your own.

--- End quote ---

Way to be an ass....

So you basically created controversy on purpose, baiting responses, instead of starting with propper "I had an idea, performed an experiment and measurements proved it was worth it"...

Did you by any chance performed frequency domain analysis so we can see what frequencies got attenuated ??

And I consider that filtering IS part of PDN....  Probably few well placed SMD capacitors placed on mainboard PCB locally would be even more gain... Also why did you place TH film capacitors across the elcos instead of ceramic SMD capacitors closer to output, or closer to high current paths to minimize current loop length.. Was there measurable difference with that placement? Did you try to put more filtering stages between PSU and mainboard?

Please tell us more. Educate us..

And yes, with MSO5000 FW version is a big deal. They have restored 500 uV/div in last FW because they have been something in their ADC algorithm lately, actually squeezing a bit less noise. That is why I asked for frequency domain measurements, to be able to see if decrease in RMS is wideband noise or discrete spurious tones...

beatman:

That is why you took out capacitors that are rated for 105°C? Because some random PCs had bad 85° capacitors 10 years ago?

Also, this power supply is basically a preregulator. Board has dozens of local regulators that are critical to signal integrity. If anything, those should be made "better". But to do so would need some real engineering, probably a respin of mainboard and would also be a point of diminishing returns, because other types of signal integrity problems would influence signal more (ground paths, crosstalk, shielding..)...
And then you have noisy front-end/ADC on MSO5000 that drowns any other interference in it's own noise floor..

It is basically a audio-foolery type of nonsense. Let's change all the capacitors for most expensive ones because "the more - the betterrer"  ((c)AvE)..

Let's see measurements before and after. Then we can see if it was worth it. So many of poor souls that do not have enough knowledge can realize it was a bad idea to disassemble perfectly working instrument (with maybe warranty) and possibly even damage it (Murphy never, ever, sleeps) to gain absolutely nothing. Except hand waving and woodo.

Or maybe it is not woodo. Maybe it was worth doing it. Easy to settle: lets see what oscilloscope measurements got better as opposed to original PSU. Hard numbers. Like: RMS and P-P  noise on 4mV/div was xx RMS and xx P-P and now is 1 or 10% better.  Or in FFT you can see that spurs at xx MHz are xx dB down ... Those kinds of things.

Or maybe statistical analysis of MTBF and defect rate on these PSU based on full battery of thermal tests in environmental chamber of say sample of 100 ?

Here's one data point for you: there are literally 10s of thousands of those sold and there has been few years now. Not to mention all kinds of similar PSU designs by same manufacturers for other scopes... And you know what ? There has been practically ZERO defects on PSU for reason you stated.
Oh, there were (expensive) Keysight scopes with PSU problem, but even those were not because of capacitors...

Or only metric that it got better is  that now you "experience the clarity of waveform presentation with nice and crisp peaks but subdued curvature of low frequency spectra and better defined pixel presentation of fine details..."        i don't say to everybody change the capacitor.the cut cost by companies is a fact.you can't compare cheap cap with brands like panasonic nippon nichicon etc in performance and life.the specs on paper are warranty.every single audio device changed capacitor or better bridge or diode sound much better and is a fact. usually i measure every (old) capacitor for mf and esr and out of the box the device have 30-40 procent down capacitance!!!in mass production save money is mandatory.only imagine what chinese crap smd is installed to everything and not everyone can see or meassure.i don't say to use extreme hi end or military components is not for everyone and the most of them is snake oil.only better good quality instead the standar bottom  category.see (badcaps forum)what capacitors goes bad.

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