Rigol MSO5000 Power Supply

[Protegimus]

Hi, has anyone already put together a BoM for upgrading components in the MSO5000 PSU?

Alternatively, any good quality images of the PSU board would be helpful. Appreciate they are gunked up.
I've been through Dave's teardown pic's, unfortunately there's not much visible.

Intent is to replace the CrapXon's with some high quality alternatives with the objective of improving noise filtering.

Others have already completed this work on different models and noted improvements.

[beatman]

I have replaced all caps with Panasonic fc.is a mater of time the cap xones goes leaky.and I am sure the psu is more quiet with better caps

[Protegimus]

Nice work beatman.
Do you have a record of what was needed that you are able to share?

Any disassembly tips?

[beatman]

Only remove the back cover and Wright the value from all capacitors to paper. mf numbers must keep the same.voltage can be little higher. when you have the new caps open again the scop unscrew the psu and careffuly to not damage the traces do the job.i hoppe you have the skills.when I see crapxones on device i replace as soon is possible

[perseverance8]

I too would like to have BOM for the MSO5K PSU, if I remember correctly the MSO5K' s PSU's enclosure is soldered on.

[beatman]

no it is not soldered.it is hold in place with 4 screws together with metal shield.once you remove the screws you need to pull the big connector from motherboard and there is one screw for the earth in mains input side that's it.on my device after the job is finished i stuck and one fat ferrite to the cables between connector and psu

[Protegimus]

Thanks for the additional information beatman.
Any chance you still have your notes on what value and voltage rating Panasonic FC's you used?

That would form an excellent base for the bill of materials.

[beatman]

FC or FR series is ok for the application.nichicon KYA Nippon LXZ alternatives do the job.one more note is to cut carefully the white glue that hold together the old caps.and with nozzle plier remove the pieces.as I said before by the same mf and same or slightly bigger voltage.all is a matter of space bigger caps Don't fit.so check dimensions before you order.

[Protegimus]

Made some progress on this.
Nice to see our MSO5000 is well constructed, disassembly is a breeze. Four torx T10 screws (highlighted yellow in image PSU connectors & screen screws) to remove the screen and PCB.

Undo the five connectors and the board is out (image PSU connectors).

BoM also attached in excel format with suggested replacements & other information.

[Protegimus]

Attached image showing additional bypass capacitors installed.

[Protegimus]

and PSU PCB with partial component overlay.

Required components list is small for the MSO5000 (full details in the BoM)
11x 1000uF 16V low ESR, e.g. Panasonic FM/FC/FR suitable
4x 470uF 16V for these I selected KEMET A750KS477M1CDAE013 aluminium organic polymer capacitors (recommended by someone that has completed recap on other Rigol models)

plus the additional TDK EPCOS metal film 0.1 & 0.01uF bypass capacitors if you wish.

C1 is already Rubycon CXW 150uF 450v and
C4 Rubycon YXJ 47uF 50v

so nothing to be done there. I also bypassed C1.

[Protegimus]

CrapXons removed and replaced.
I gunked them up again as per OEM to prevent vibration.

Will do the remaining caps once I receive inventory.

Can anyone identify U4 & U11 marked L2107?

I have lots more images if anyone is interested.

[Sighound36]

This is an excerise I performed on the MSO 8000 & RSA5065 about three years ago they use the same SMPS unit.

Definiately a worthwhile excerise especially on the spectrum analyser, I also went further a few months later, however I didn't change take any further images sorry about.

[ballsystemlord]

and PSU PCB with partial component overlay.

Required components list is small for the MSO5000 (full details in the BoM)
11x 1000uF 16V low ESR, e.g. Panasonic FM/FC/FR suitable
4x 470uF 16V for these I selected KEMET A750KS477M1CDAE013 aluminium organic polymer capacitors (recommended by someone that has completed recap on other Rigol models)

I only count 9 1000uf in the BOM. Which is it?
Also, the originals don't appear to be low ESR. Is there someone who tested and found that low ESR caps work better or is this more because you can?

plus the additional TDK EPCOS metal film 0.1 & 0.01uF bypass capacitors if you wish.

Why bypass capacitors? Maybe you've read someone else's work that goes into detail on these matters which you could link?

Thanks!

PS: I'm asking because I own an MSO5000.

[ballsystemlord]

Even more interesting, why bother replacing all those capacitors if you could just place a few on the output stage to filter the PSUs natural noise level?

[beatman]

I thing bypass caps is for audio big capacitance capacitors to get more quick charge discharge

[Protegimus]

CapXon KF datasheet http://images.100y.com.tw/pdf_file/05-CAPXON-KF.pdf.
Panasonic FM better the specification of the crapxon part in terms of low impedance characteristic (and pretty much every other specification), datasheet https://www.mouser.co.uk/datasheet/2/315/ABA0000C1018-947496.pdf.

Panasonic FR and KEMET A series are also classed as low impedance parts with suitability for use in PSUs, again bettering the specification of the crapxons. Sighound36 has generously already shared his positive results. If you can find improved alternatives that fit, then please post your recommendation and references.

Addressing the question of why bypass. Take a look at the attached PYJD_PB0575_V1.00 bypass capacitors_02 image.
I've highlighted red C12-C16 ceramic SMD capacitors Rigol fitted for the same purpose, i.e. additional noise filtering.
I've just taken that further and also bypassed on the first part of the CRC filter, whereas Rigol implemented it on the latter. Capacitor values set the corner frequency for the filter, hence the use of additional values.
Yes, the methodology is extensively utilised in high quality audio equipment.
Fesz Electronics has some excellent videos, including a series on decoupling capacitors
Can we leave it at that re bypassing so as not to lose focus on the PSU. It's up to you whether you want to implement it and if you want to start a detailed discussion you're free to open another thread.

Also attached is the updated BoM v0.2
Not all components are fully identified, e.g. CS1, as some of the PCB silk screen is obscured by gunk. It's a work in progress, amendments/corrections are welcome.

[Protegimus]

Additional information on disassembly available in the MSO-5000E manual available here:
https://www.rigol.eu/Public/Uploads/uploadfile/files/ftp/%E6%96%B0%E8%B5%84%E6%96%99%E5%BA%93-%E5%90%AB%E6%89%8B%E5%86%8C%E5%9B%BA%E4%BB%B6%E8%BD%AF%E4%BB%B6/%E5%AE%98%E7%BD%91%E8%B5%84%E6%96%99/DS/%E6%89%8B%E5%86%8C/MSO5000-E/EN/MSO5000-E_ServiceGuide_EN.pdf

MSO-5000E limited 2 channel 150MHz bandwidth version, but chassis is the same.

[ballsystemlord]

Can we leave it at that re bypassing so as not to lose focus on the PSU. It's up to you whether you want to implement it and if you want to start a detailed discussion you're free to open another thread.

Also attached is the updated BoM v0.2
Not all components are fully identified, e.g. CS1, as some of the PCB silk screen is obscured by gunk. It's a work in progress, amendments/corrections are welcome.

Thanks for getting back to me.
I wasn't trying to take the thread some other direction. Just understand why you made the decisions you did. Being a student, there's still a lot IDK about electronics.

[tautech]

Can we leave it at that re bypassing so as not to lose focus on the PSU. It's up to you whether you want to implement it and if you want to start a detailed discussion you're free to open another thread.

Also attached is the updated BoM v0.2
Not all components are fully identified, e.g. CS1, as some of the PCB silk screen is obscured by gunk. It's a work in progress, amendments/corrections are welcome.

Thanks for getting back to me.
I wasn't trying to take the thread some other direction. Just understand why you made the decisions you did. Being a student, there's still a lot IDK about electronics.

Thinking they know better than designers.
Nothing wrong with CapXon caps when design and application meets their spec.

Never had any issues with them in gear we sell in 10 yrs.
Don't believe all that is spouted on forums.

[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]

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.

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]

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.

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.