Rigol's New DHO800 Oscilloscope unbox & teardown

[2N3055]

Thank you!  but I know this very well, are you saying that the measurements taken above by Tektronix are reliable?  Does Tektronix have the necessary counter to count the number of synchronization pulses in one second?  or does he calculate some average value when indicating the signal frequency?.... please enlighten me.

Could you please point to exact post you are talking about?

Any real counter that does physical counting in a 1 sec gate will do good job.

[AndyBig]

I don’t know if anyone has posted the insides of the new LiteOn PA-1650-58 power supply, but I don’t think I’ve seen it
The case is glued together very carefully; it is impossible to disassemble it without serious damage. In my opinion, the quality of the power supply is very good, this is not a cheap Chinese power supply with the maximum reduction in price. As for the rest, I don’t dare to comment, since I’m not well versed in switching power supplies.

[AndyBig]

More photos of the power supply.

[Mechatrommer]

I don’t know if anyone has posted the insides of the new LiteOn PA-1650-58 power supply, but I don’t think I’ve seen it
The case is glued together very carefully; it is impossible to disassemble it without serious damage. In my opinion, the quality of the power supply is very good, this is not a cheap Chinese power supply with the maximum reduction in price. As for the rest, I don’t dare to comment, since I’m not well versed in switching power supplies.

thanks for doing the job for us... https://www.eevblog.com/forum/testgear/rigols-new-dho800-oscilloscope-unbox-teardown/msg5125530/#msg5125530

[AndyBig]

thanks for doing the job for us... https://www.eevblog.com/forum/testgear/rigols-new-dho800-oscilloscope-unbox-teardown/msg5125530/#msg5125530

Oops, apparently I was inattentive when I re-read the topic

[Mechatrommer]

thanks for doing the job for us... https://www.eevblog.com/forum/testgear/rigols-new-dho800-oscilloscope-unbox-teardown/msg5125530/#msg5125530

Oops, apparently I was inattentive when I re-read the topic

dont worry, you dont have to, as long as you are capable man to make your own content it will need more brave people to do it cheers.
https://www.eevblog.com/forum/testgear/rigols-new-dho800-oscilloscope-unbox-teardown/msg5134716/#msg5134716
https://www.eevblog.com/forum/testgear/rigols-new-dho800-oscilloscope-unbox-teardown/msg5125968/#msg5125968

[AndyBig]

dont worry, you dont have to, as long as you are capable man to make your own content it will need more brave people to do it cheers.
https://www.eevblog.com/forum/testgear/rigols-new-dho800-oscilloscope-unbox-teardown/msg5134716/#msg5134716
https://www.eevblog.com/forum/testgear/rigols-new-dho800-oscilloscope-unbox-teardown/msg5125968/#msg5125968

Ah... Well, usually if I start to disassemble out of curiosity, I don’t stop until I see everything Even if this is beyond my competence (like switching power supplies), I still have to see how everything is assembled, on what element base and etc.
By the way, the screen easily comes off the compound. But the compound itself is interesting, I have never encountered anything like it before - much harder than silicone, almost like plastic, but still a little elastic.

[beatman]

This material used in all laptop psus packs.I think is thermal conductive the adapter gets really hot and heat transfer out from the plastic case. Stuffing the psu like this to avoid vibrations (and thermal transfer)and do the parts service nightmare.

[GnomeZA]

This material used in all laptop psus packs.I think is thermal conductive the adapter gets really hot and heat transfer out from the plastic case. Stuffing the psu like this to avoid vibrations (and thermal transfer)and do the parts service nightmare.

I wonder if that hot glue is really thermally conductive.  I have my doubts.  But I've replaced glue and things like that with RTV in the past.  Not even the expensive RTV you get for electronics (with better thermal properties).  I just straight up buy the RTV used for car gasket making (ie. JBWeld ultimate RTV) and it has worked exceptionally well.

[AndyBig]

This material used in all laptop psus packs.I think is thermal conductive the adapter gets really hot and heat transfer out from the plastic case. Stuffing the psu like this to avoid vibrations (and thermal transfer)and do the parts service nightmare.

I also have a suspicion that this compound is thermally conductive. It feels cold in your hands for quite a long time, not like plastic, which quickly becomes warm. And when leaned against a hot soldering iron, it heats up very quickly throughout its entire volume. I think that it serves here to remove heat from the elements to a metal shield that has a large area.
I have already decided that I will refill the power supply board with the thermally conductive silicone compound I have

[ebastler]

I just straight up buy the RTV used for car gasket making (ie. JBWeld ultimate RTV) and it has worked exceptionally well.

How do you measure this "exceptionally good" performance, and how much long-term experience do you have with the stuff? To my knowledge, JB-Weld ultimate RTV is an example of Acetoxysilane-based silicone. It releases acetic acid while curing. I would certainly not use it on electronics.

[beatman]

RTV maybe is good for hold things in place capacitors transformers etc. but not to cover the whole pcb my opinion.The white compound on pc packs is the material for that.I don't know the name of it to find on market.I have a tube with white thermal conductive glue to hold in top of ic's small aluminium coolers and it locks about the same when is dry.

[Veteran68]

Sounds like some of you are talking about common white "silastic."

Dow 744 White seems to be one of the most common electronics silicone adhesives, though "silastic" is not part of it's name or description unlike other Dow silastic products (there are many formulations).

Pretty sure it's not very thermally conductive though. That requires specialized silicone formulations like SilicoTherm that include thermally conductive fillers such as aluminum oxides. Careful though you don't pick one of the electrically conductive silicone formulations, unless that's what you actually want!

[AndyBig]

The main thing is that the silicone compound must be neutral. This is usually indicated on the packaging. This silicone does not release acetic acid during polymerization and does not harm tracks, contacts and components.
If silicone smells like vinegar, it means it is acidic and cannot be used in electronics.
The thermal conductivity of ordinary silicones is low, but there are special thermally conductive silicones, which, as written above, contain a thermally conductive filler - usually special ceramics.

[GnomeZA]

How do you measure this "exceptionally good" performance, and how much long-term experience do you have with the stuff?

Long term, not so much, I'd say I've been using it for 2-3 years on and off.
Exceptionally good performance is subjective ofc but the devices typically had better thermal performance than they did before (ie. temperature sensor before and after).

The reason I started using it is because in the 3d printer space we use this stuff to adhere AC powered 500->1000 watt heaters to Aluminium beds and it performs better in than the 3m adhesives commonly used by those AC heaters in that respect.

You aren't going to get charts from me, I haven't prepared a thesis on this, it is my opinion.

To my knowledge, JB-Weld ultimate RTV is an example of Acetoxysilane-based silicone. It releases acetic acid while curing. I would certainly not use it on electronics.

True it does release acetic acid, at least from the smell.  I've not had any issues, but to your point, probably best not to use it on expensive equipment or during manufacture.  But I'm a lot less absolute about my insistence on perfection.  Especially where price is concerned.  The alternatives cost 10 times as much.  If you can afford to pay 10 times as much go for it (although at that point I question why you don't just buy another item).

[ebastler]

True it does release acetic acid, at least from the smell.  I've not had any issues, but to your point, probably best not to use it on expensive equipment or during manufacture.  But I'm a lot less absolute about my insistence on perfection.  Especially where price is concerned.  The alternatives cost 10 times as much.  If you can afford to pay 10 times as much go for it (although at that point I question why you don't just buy another item).

Well, if the acid it destroys my devices over time, that will cost me much more than the cost of neutral silicone -- even when you just look at hardware cost, and worse when you also attach a price to the time and hassle of replacing or fixing it later.

[GnomeZA]

Well, if the acid it destroys my devices over time, that will cost me much more than the cost of neutral silicone -- even when you just look at hardware cost, and worse when you also attach a price to the time and hassle of replacing or fixing it later.

Pretty sure the acetic acid evaporates.
But we have no data, this is going to turn into a whose d#ck is bigger kind of thing.
I hear what you are saying and agree there is a risk.

[AndyBig]

Pretty sure the acetic acid evaporates.

From the surface of the sealant - of course, and quite quickly. But from the surface of the board and components under the sealant layer - very, very slowly. In fact, it ends up locked there in a sealed volume.

[Veteran68]

The fact that acetic acid based formulations can and will corrode or degrade electronic components is well documented. That's why non-acidic formulations exist and are specified for electronics work.

[GnomeZA]

The fact that acetic acid based formulations can and will corrode or degrade electronic components is well documented.

Do you have a link I could look at?

[Randy222]

WTF...
When i adjust minimum vertical division，it has a large ripple at 55KHz and large noice....
I guess it may come from power supply.

My 804 (recent build) that came with the 01.02 FW does show noise on the DC of the PSU, but I don't see it leaking into the front-end when the channels are on with floating inputs.

I took a look at the DC being supplied to the 804 --> https://www.eevblog.com/forum/testgear/hacking-the-rigol-dho800900-scope/msg5245911/#msg5245911

[ebastler]

That post from Azusa refers to the early DHO800 units, which were shipped with a very cheap, fixed 12V switching supply. This caused real problems, and Rigol reacted by upgrading to better power supplies (Liteon or Lenovo brands have been reported).

I don't think you need to be worried about your Liteon supply. As you said, it does not affect measurements, so it's not really critical what the incoming DC voltage looks like.

[Veteran68]

The fact that acetic acid based formulations can and will corrode or degrade electronic components is well documented.

Do you have a link I could look at?

Not trying to be a smartass, but Google is your friend here. As I said, it's well documented. But to show what a nice guy I am here's a couple of quick hits to get you started:

https://www.masterbond.com/techtips/why-use-silicone-adhesive

Silicone adhesives boast excellent electrical properties and can be formulated to be insulative with a high dielectric strength, or conversely electrically conductive. Many one part silicone adhesives release a corrosive entity, such as acetic acid, but there are special formulations that are totally non-corrosive and can be used with electronics. These are often used as a conformal coating for electronic circuit boards. Silicone systems are also used for sealing cables and sensors in both appliances and electronics.

https://cht-silicones.com/faq/is-silicone-safe-for-electronics

Is silicone safe for electronics?

CHT manufacture silicones that are safe to use on electronics.

You should avoid silicone adhesive sealants which use Acetoxy crosslinkers. Neatral cure silicones are safe to use with electronics as any by-products of the cure system are non-corrosive.

https://qualitysealaustralia.com.au/acetoxy-vs-neutral-cure-silicone (mainly builder related but references the danger to electronics)

Acetoxy silicone, as we previously discussed, is very corrosive because of its significant amount of acetic acid. This may cause discoloration when used on natural stone. When applied to bituminous materials, such as some types of roofing material, carpet tiles, paints, and waterproof coatings, it can cause the bitumen to “bleed.”

Acetoxy silicone must be kept away from delicate electronics while it cures because the resulting fumes may damage electronics. Brass and copper are among the metals that can be harmed by acetic acid.

[Randy222]

That post from Azusa refers to the early DHO800 units, which were shipped with a very cheap, fixed 12V switching supply. This caused real problems, and Rigol reacted by upgrading to better power supplies (Liteon or Lenovo brands have been reported).

I don't think you need to be worried about your Liteon supply. As you said, it does not affect measurements, so it's not really critical what the incoming DC voltage looks like.

Since I don't know I have to ask.
How did just swapping out the USB-C PSU mitigate the ripple/noise that was leaking into front end? I mean, my 804 came with the newer Liteon and I still see about the same noise pattern on the DC that was posted with the old PSU.

[AndyBig]

Since I don't know I have to ask.
How did just swapping out the USB-C PSU mitigate the ripple/noise that was leaking into front end? I mean, my 804 came with the newer Liteon and I still see about the same noise pattern on the DC that was posted with the old PSU.

Is your oscilloscope noise similar to this? I also can’t figure out what this noise is and where it comes from. It appears only if you connect a probe; without a probe (with an open input or with a 50 Ohm load at the input) it does not exist.
The ground lead is short-circuited to the central pin, the probe is located approximately 30 cm from the oscilloscope. In the channel settings, the 20 MHz BW limit is disabled, the divider is set to 10x. I provided screenshots on different horizontal scans.