Hacking the Rigol DHO800/900 Scope

[Mechatrommer]

Three photos of underside of CPU in original & unmodified DHO924S. If somebody wants more photos of something particular - better tell me now.

if this images came earlier, we will not have try and error. but maybe for good, AndyBig will not provide us with circuit schematics. now we know how to make more combination to make HW12 or 8 (your showing 1101 as i discovered earlier)

Shaky hands and naked eye.

thats the adc input path... analog input is just down below... 4 of them now you are so bold to solder CH4 path in such a way

[norbert.kiszka]

Shaky hands and naked eye.

thats the adc input path... analog input is just down below... 4 of them

No... That was aftermath of my first modification.

[norbert.kiszka]

No... That was aftermath of my first modification.

anyway you are doing mod that i cannot imagine i would go..

That was three stage low pass filter. Now this is a one stage only.

BTW. I have much bigger coils than those four I removed. Size about 1/3 of this scope and rated to 35 A.

[Mechatrommer]

No... That was aftermath of my first modification.

anyway you are doing mod that i cannot imagine i would go..

That was three stage low pass filter. Now this is a one stage only.

that is somehow if i'm correct to control signal integrity in differential signal into ADC, not anything to do with dso analog input respond. you probably change the phase or time delay too.. should you be more clearer you are planning to make it 2 or 5 GSps?

[norbert.kiszka]

No... That was aftermath of my first modification.

anyway you are doing mod that i cannot imagine i would go..

That was three stage low pass filter. Now this is a one stage only.

that is somehow if i'm correct to control signal integrity in differential signal into ADC, not anything to do with dso analog input respond. you probably change the phase or time delay too.. should you be more clearer you are planning to make it 2 or 5 GSps?

More like a filters to lower bandwidth, to force You to buy more expensive scope. This puppy is very small, lightweight and very good to transport it. DHO4000 not so much.

Anyway, resistors before adc (measured in circuit) are 85 ohms - for each channel.

[Mechatrommer]

More like a filters to lower bandwidth, to force You to buy more expensive scope. This puppy is very small, lightweight and very good to transport it. DHO4000 not so much.

i hope you success with your SW/FW mod without burning anything. it will be more fun to have 4GSps at $400

Anyway, resistors before adc (measured in circuit) are 85 ohms - for each channel.

impedance matching to avoid reflection?

[AndyBig]

There was already a description of increasing the analog bandwidth to 400 MHz by replacing inductors.

[norbert.kiszka]

More like a filters to lower bandwidth, to force You to buy more expensive scope. This puppy is very small, lightweight and very good to transport it. DHO4000 not so much.

i hope you success with your SW/FW mod without burning anything. it will be more fun to have 4GSps at $400

Anyway, resistors before adc (measured in circuit) are 85 ohms - for each channel.

impedance matching to avoid reflection?

For 100%. But I was expecting 50 ohms.

There was already a description of increasing the analog bandwidth to 400 MHz by replacing inductors.

I know. I did "replacing" as You can see.

[AceyTech]

Speaking of additional calibration options..  I hadn't noticed this before tonight.  There is a "Detail" drop-down on the SelfCal window with some interesting calibration info. -if it passes- 
(Attachment Link)
BTW: these are all the "additional calibration" options that I found to calibrate with success.  Anything else added will fail. 
(Attachment Link)
FYI: it took 7 hours to test all the permutations, because some would go 98 or 99% before stopping or crashing.

The cal items seen after x3 About press, is a bit confusing. Are the ones selected by default the same items used when you just have the std Cal menu of "start"? Or is the std set something different? Is that in the manual?
Rigol should at least identify which ones selected are in the std set of cal tests. And why does selecting the other tests fail? If they are tests not applicable to the device then they should be grayed out. If they are applicable tests and they fail, why do they fail?

From my photo; The bottom row of SelfCal items are not selected in a factory stock configuration(at least with my 804), and I doubt there's any reason to believe there's any differences related to SelfCal between authentic 800 and 900's, since they use the same software package.
Through many hours of calibration testing, I was able to figure out you could also do each of the items in the bottom row without premature exit failure.


I captured the default 1, 2, 3 SelfCal screen before I did this testing.


Why do some items fail SelfCal?  Might be able to capture that info in the log file. and, FWIW as I mentioned the "interesting details" triangle has a log as it's calibrating, as I showed in that pic.  Maybe it's there.  Or via Serial terminal... or k(d)mesg.last, or logcat, etc...  (you're the Android expert, not me!)

[Mechatrommer]

There was already a description of increasing the analog bandwidth to 400 MHz by replacing inductors.

where?

[Randy222]

AFG is commanded by FPGA and vendor.bin hack to 900 alone will activate it even on HW12, so far no differences that i can spot. bode plot was working fine in HW12. btw checking start_rigol_app.sh i spotted there is another afg_gpio.ko module is loaded if anyone interested, so far i am not interested in wasting time on it since every AFG functionalities that i expect to work, work as expected either on HW12 or 8. the point we looked for HW8 is because we want the 16CH digital channels can be used as trigger source correctly. this has some applications, but if you dont need it, thats fine for you.

The afg KLM uses 5 pins in gpio3, gpio 122,123,124,125,126, using odd name "afg_in1" , odd in that uses the word "in" but the pin is an out pin, and on my 804 are set 10101

[AceyTech]

From the DHO800 Datasheet.


--This looks nothing like 50\$\Omega\$ to me.



Pretty sure we would need an extra relay and some resistors, and some software to turn 50 ohms on/off, like in the DHO1000.

FYI:  This info is for Norbert

[Mechatrommer]

AFG is commanded by FPGA and vendor.bin hack to 900 alone will activate it even on HW12, so far no differences that i can spot. bode plot was working fine in HW12. btw checking start_rigol_app.sh i spotted there is another afg_gpio.ko module is loaded if anyone interested, so far i am not interested in wasting time on it since every AFG functionalities that i expect to work, work as expected either on HW12 or 8. the point we looked for HW8 is because we want the 16CH digital channels can be used as trigger source correctly. this has some applications, but if you dont need it, thats fine for you.

The afg KLM uses 5 pins in gpio3, gpio 122,123,124,125,126, using odd name "afg_in1" , odd in that uses the word "in" but the pin is an out pin, and on my 804 are set 10101

you gave me some idea, because i have 3 unknown pins on AFG interface, 1 is output i think and the other 2 pins probably input. if there is way knowing what RK3399 pins refered as 122-126... maybe i need to look into afg_gpio.ko more closely. thanks.

[AceyTech]

...... odd in that uses the word "in" but the pin is an out pin, and on my 804 are set 10101

But there is no AFG in a 804.  Why would they care if the AFG pins were set on a non-900S model?  Or am I missing something?

[norbert.kiszka]

There was already a description of increasing the analog bandwidth to 400 MHz by replacing inductors.

where?

Long time ago in this topic or in teardown&bugs topic. Same input stages and ADC are in DHO1000 and DH4000. This second one has nominal bandwith of 800 MHz.

Anyway, 50 ohm switch is in app, but is hidden. Its shown when You put vendor.bin generated for DHO4000. Its a matter of decompile, change and compile it back. After that add transistor, resistor, diode, relay and resistor... I was just going just to add 4 parallel 0.25W 200 ohm resitors into channel 4 after adding buch of capacitors into empty missing pads and couple other places...

[AceyTech]

There was already a description of increasing the analog bandwidth to 400 MHz by replacing inductors.

where?

I will probably regret this., but here is the link to the 400+ Mhz post... From Feb 17th.

Oh, and @Mechatrommer, you even commented a few links later.

[AceyTech]

Long time ago in this topic or in teardown&bugs topic. Same input stages and ADC are in DHO1000 and DH4000. This second one has nominal bandwith of 800 MHz.

I am not trying to speak for everyone here., but it seems to me like you bought the wrong Oscilloscope.(being a 924S)  Perhaps you should sell it and buy a DHO1000 and hack the snot out of that one?  Much more capable platform.

Just Sayin'.

[norbert.kiszka]

AFG is commanded by FPGA and vendor.bin hack to 900 alone will activate it even on HW12, so far no differences that i can spot. bode plot was working fine in HW12. btw checking start_rigol_app.sh i spotted there is another afg_gpio.ko module is loaded if anyone interested, so far i am not interested in wasting time on it since every AFG functionalities that i expect to work, work as expected either on HW12 or 8. the point we looked for HW8 is because we want the 16CH digital channels can be used as trigger source correctly. this has some applications, but if you dont need it, thats fine for you.

The afg KLM uses 5 pins in gpio3, gpio 122,123,124,125,126, using odd name "afg_in1" , odd in that uses the word "in" but the pin is an out pin, and on my 804 are set 10101

you gave me some idea, because i have 3 unknown pins on AFG interface, 1 is output i think and the other 2 pins probably input. if there is way knowing what RK3399 pins refered as 122-126... maybe i need to look into afg_gpio.ko more closely. thanks.

When You decompile kernel module from this scope, look also into same module from DHO1000/DHO4000 (same updates for both and modules are there). Some are different and some are the same. This second one has more k. modules.

[shapirus]

From my photo; The bottom row of SelfCal items are not selected in a factory stock configuration(at least with my 804), and I doubt there's any reason to believe there's any differences related to SelfCal between authentic 800 and 900's, since they use the same software package.

Before trying "AFE Zero", do back up your current cal files. It is known to screw up calibration, and it's not clear if there's any way to restoring from that bad state other than pushing the good cal files back to the scope.

I've had this issue.

[AceyTech]

From my photo; The bottom row of SelfCal items are not selected in a factory stock configuration(at least with my 804), and I doubt there's any reason to believe there's any differences related to SelfCal between authentic 800 and 900's, since they use the same software package.

Before trying "AFE Zero", do back up your current cal files. It is known to screw up calibration, and it's not clear if there's any way to restoring from that bad state other than pushing the good cal files back to the scope.

I've had this issue.

Good point, for anyone following along.  Thanks!
BTW: I wasn't advocating performing SelfCal on those additional items.  I decided to "try" them to see which ones crashed or not.

[Mechatrommer]

There was already a description of increasing the analog bandwidth to 400 MHz by replacing inductors.

where?

I will probably regret this., but here is the link to the 400+ Mhz post... From Feb 17th.

Oh, and @Mechatrommer, you even commented a few links later.

i cant read nor see pictures in that forum. I was commenting in general idea without looking specifically. Just watched back dave video, he said front end could be 800MHz, but this need verification. I probably misunderstood rt4612iq afe (i thought adc) and if is differential signal analog?

[Mechatrommer]

...... odd in that uses the word "in" but the pin is an out pin, and on my 804 are set 10101

But there is no AFG in a 804.  Why would they care if the AFG pins were set on a non-900S model?  Or am I missing something?

i guess because they code once compatible for all. design once for both 800 and 900. Dave talked about reducing NRE? about man power cost.

[Mechatrommer]

Anyway, 50 ohm switch is in app, but is hidden. Its shown when You put vendor.bin generated for DHO4000. Its a matter of decompile, change and compile it back. After that add transistor, resistor, diode, relay and resistor... I was just going just to add 4 parallel 0.25W 200 ohm resitors into channel 4 after adding buch of capacitors into empty missing pads and couple other places...

you typed about heating pcb and resistor risk. Now you want to do more heavy metal to make your scope spaggetti mess whats wrong with $1 external inline 50 ohm teminator? spend a little bit more if u want quality.

[AceyTech]

...... odd in that uses the word "in" but the pin is an out pin, and on my 804 are set 10101

But there is no AFG in a 804.  Why would they care if the AFG pins were set on a non-900S model?  Or am I missing something?

i guess because they code once compatible for all. design once for both 800 and 900. Dave talked about reducing NRE? about man power cost.

Yes yes.  I think you misunderstood my Q. which is intended as a statement to Randy's question.  He was asking about the "direction bits" register(pertaining to ARB) being set to in or out.

[AndyBig]

i cant read nor see pictures in that forum. I was commenting in general idea without looking specifically. Just watched back dave video, he said front end could be 800MHz, but this need verification. I probably misunderstood rt4612iq afe (i thought adc) and if is differential signal analog?

Yes, a differential signal goes from rt1642 to the ADC. And from the ADC to the FPGA it is also differential, but digital.