Hacking the Rigol MSO5000 series oscilloscopes

[TopLoser]

Somebody asked me to post a photo of my 'system information' screen.

Were you a beta tester???   

I built it from kit form, after it had been totally dismantled and various IC's removed for 'QC' inspection 

[oliv3r]

Back on page 10 was it? Vtech made an excellent post finding out a lot of the cool chips with Dave's video.

I figured, we need a pic and some more text to go with that. But not any ol'e pic. I took the front and back pictures from Dave's teardown, and overlayed them. Then made the bottom 50% transparant allowing us to see a little bit more what's going on



For more information (what the colors mean etc) see https://gitlab.com/riglol/rigolee/wikis/MSO5000-teardown

Edit: Also did the keyboard

For more information see https://gitlab.com/riglol/rigolee/wikis/MSO5000-teardown

[helmy]

Did anyone try to make their own (PLA2216) logic probe for cheap, considering it is priced at $400!

[TopLoser]

Did anyone try to make their own (PLA2216) logic probe for cheap, considering it is priced at $400!

https://www.eevblog.com/forum/testgear/rpl1116-active-logic-probe-pod-for-1000z-series-teardown/

[mikeselectricstuff]

Did anyone try to make their own (PLA2216) logic probe for cheap, considering it is priced at $400!

Should be easy enough as it's just a bunch of ECL comparators.  Probably just a matter of time before they show up on Aliexpress

[tv84]

What does this image show?

(It's a MSO5000 capture, with a 50-ohm termination.)

[thomil]

What does this image show?

350ps fal time? 1GHz bandwidth?

[Fungus]

What does this image show?

350ps fal time? 1GHz bandwidth?

It's displaying a pulse that's approx. 1ns.

[johnmx]

What does this image show?

What is your signal source?
It would be interesting to see the same response using a 50 Ohm terminator at the scope input.
E.g. something like this may prevent oscillations at higher frequencies:
https://www.picotech.com/accessories/bnc-terminators-leads/50r-terminator-bnc

[Fungus]

It's a transistor catching fire?

[tv84]

It's a transistor catching fire?

We are almost OT but I would like to see if you guys confirm that this can be used as proof of the claims that were made a few weeks ago...

BTW, Fungus, can you recreate this with your (any) scope?

[iMo]

The rise time is important with that test, afaik.
BW=350/0.44=795MHz

[Fungus]

It's a transistor catching fire?

We are almost OT but I would like to see if you guys confirm that this can be used as proof of the claims that were made a few weeks ago...

BTW, Fungus, can you recreate this with your (any) scope?

I haven't got a 90V DC supply. Mine only goes up to 30V.

(I assume that applying 90V to that transistor is bad, hence my comment)

[Noy]

Fungus searching for "Avalanche Pulser" then you will know what it is.
And that 90V ist OK for an Avalanche Transistor...

[TurboTom]

Btw, that resistance in series with the power supply is MegOhm, not milliOhm as the schematic may suggest... 

[johnmx]

I wonder if the oscillations are from the circuit itself instead of the impedance mismatch of the scope input stage

[tcottle]

Fungus searching for "Avalanche Pulser" then you will know what it is.
And that 90V ist OK for an Avalanche Transistor...

http://www.eevblog.com/2012/07/06/eevblog-306-jim-williams-pulse-generator/

[rgwan]

It's a transistor catching fire?

We are almost OT but I would like to see if you guys confirm that this can be used as proof of the claims that were made a few weeks ago...

BTW, Fungus, can you recreate this with your (any) scope?

The frontend of this scope has very poor S11 performance, measured by KC901 VNA. Although we added a 50-ohm terminator to its input, S11 curve above 350MHz still looks terrible. We have swept this scope by HP 8657 generator, usable bandwidth is around 380MHz. Maybe the internal match network on AFE's output line limited the bandwidth and the input circuit isn't capable of high-frequency usage (because of such high S11).

[TheSteve]

Did you calibrate the KC901V to remove the cable effects?
Have you checked the return loss of the terminator itself?
Can you run it with a lower max frequency as anything above 500 MHz/ 1 GHz is likely meaningless.

Lastly many scopes 50 ohm inputs are only rated to have an SWR of 1.5:1 or better - that is only 14 dB of return loss.

[rgwan]

Did you calibrate the KC901V to remove the cable effects?
Have you checked the return loss of the terminator itself?
Can you run it with a lower max frequency as anything above 500 MHz/ 1 GHz is likely meaningless.

Lastly many scopes 50 ohm inputs are only rated to have an SWR of 1.5:1 or better - that is only 14 dB of return loss.

1、Yes.
2、Of course.
3、I have done it, it doesn't look good... Almost the same result as this. Below 350MHz it is fine though, but in 350MHz-1GHz, if you don't do some hardware modification, it is not as good as the calculated bandwidth that the pulse response result shown by tv84. I have returned home for winter vacation, about 1 month or so I can't do any measurement for this scope (because I haven't equipment to measure at home) ...

[TheSteve]

I don't think you're seeing any problem with the scope, it is just the nature of trying to use a 50 ohm feed through connected to the 1 meg-ohm input of a scope. A scope with a 50 ohm internal path is optimized for such things. Using a feed-through will only match a proper 50 ohm input at very low frequencies.
Here is an example of what my Keysight scope looks like with its native 50 ohm input, and then using a 50 ohm feed-through with the scope input back at 1 meg-ohm. It looks absolutely horrible using the feed-through. The third shot is the 50 ohm feed-through on its own just for reference.

[rgwan]

I don't think you're seeing any problem with the scope, it is just the nature of trying to use a 50 ohm feed through connected to the 1 meg-ohm input of a scope. A scope with a 50 ohm internal path is optimized for such things. Using a feed-through will only match a proper 50 ohm input at very low frequencies.
Here is an example of what my Keysight scope looks like with its native 50 ohm input, and then using a 50 ohm feed-through with the scope input back at 1 meg-ohm. It looks absolutely horrible using the feed-through. The third shot is the 50 ohm feed-through on its own just for reference.

I mean this scope is not designed for testing above 350MHz signal. It just not perform well and maybe it needs some hardware modification to make use of the high sample rate.

[2N3055]

I don't think you're seeing any problem with the scope, it is just the nature of trying to use a 50 ohm feed through connected to the 1 meg-ohm input of a scope. A scope with a 50 ohm internal path is optimized for such things. Using a feed-through will only match a proper 50 ohm input at very low frequencies.
Here is an example of what my Keysight scope looks like with its native 50 ohm input, and then using a 50 ohm feed-through with the scope input back at 1 meg-ohm. It looks absolutely horrible using the feed-through. The third shot is the 50 ohm feed-through on its own just for reference.

I mean this scope is not designed for testing above 350MHz signal. It just not perform well and maybe it needs some hardware modification to make use of the high sample rate.

You cannot just hack it.. For higher frequencies you need to use 50 OHm path, and that has to exist in the scope from input connector to A/D converter. It has to be controlled impedance layout.
Basically, it has to exist as separate part of PCB made for just that purpose that is just not there on MSO5000 board.

Chipset and front end chip in MSO7000 and MSO5000 is identical and capable of same bandwidth (frontend chipset is capable of few GHz actually). It's just that your signal from input BNC cannot get to it without being destroyed.
For a scope of this class it is more important that it has good 300 MHz with good signal integrity(which is a miracle itself), that hacking it to 1GHz with distorted signal. You get worse scope actually, and much more noise...

[rgwan]

I don't think you're seeing any problem with the scope, it is just the nature of trying to use a 50 ohm feed through connected to the 1 meg-ohm input of a scope. A scope with a 50 ohm internal path is optimized for such things. Using a feed-through will only match a proper 50 ohm input at very low frequencies.
Here is an example of what my Keysight scope looks like with its native 50 ohm input, and then using a 50 ohm feed-through with the scope input back at 1 meg-ohm. It looks absolutely horrible using the feed-through. The third shot is the 50 ohm feed-through on its own just for reference.

I mean this scope is not designed for testing above 350MHz signal. It just not perform well and maybe it needs some hardware modification to make use of the high sample rate.

You cannot just hack it.. For higher frequencies you need to use 50 OHm path, and that has to exist in the scope from input connector to A/D converter. It has to be controlled impedance layout.
Basically, it has to exist as separate part of PCB made for just that purpose that is just not there on MSO5000 board.

Chipset and front end chip in MSO7000 and MSO5000 is identical and capable of same bandwidth (frontend chipset is capable of few GHz actually). It's just that your signal from input BNC cannot get to it without being destroyed.
For a scope of this class it is more important that it has good 300 MHz with good signal integrity(which is a miracle itself), that hacking it to 1GHz with distorted signal. You get worse scope actually, and much more noise...

Yes, that is actually what I mean. To make use of the high sample rate isn't easy.

[PA0PBZ]

Here is an example of what my Keysight scope looks like with its native 50 ohm input, and then using a 50 ohm feed-through with the scope input back at 1 meg-ohm. It looks absolutely horrible using the feed-through. The third shot is the 50 ohm feed-through on its own just for reference.

Can you explain why above 800MHz the feedthrough + scope seems better than the feedthrough alone? Is the feedthrough not made for frequencies above 500MHz or something like that?