Hacking the Rigol DHO800/900 Scope

[Serg65536]

How to use the scope as an android tablet
With sound!

0) Open your scope and make full backup of the MicroSD card, with the "HDD Raw Copy Tool" for eg. (compressed image takes ~500MB of disk space only)

1) Find any USB headphones (or other USB sound device identified as headphones with default driver in windows. I've checked two old ones and both are working.).

2) Find a USB hub.

3) Find a USB keyboard with the "home" key.

4) Connect 1), 2) and 3) to the scope. (Reboot was not required in my case, press "win+n" to access system notifications bar, sound levels and settings).

5) Install some simple launcher:
adb connect
adb install yourSimpleLauncherName.apk

6) Install chrome (the last version for the android 7 is chrome 119.0.6045.194, probably, it will argue for absence of play services, but will launch nevertheless).

7) PRESS "Stop" BUTTON (it's required to release CPU resources).

8 ) Press "Home" button on the USB keyboard, select yourSimpleLauncherName and press "always". (This will substitute the com.rigol.launcher, but scope should initialize successfully anyway).

9) Now on boot yourSimpleLauncher should always launch before the "com.rigol.scope" application, and you should be able to switch to yourSimpleLauncher with the "home" key, or with the "alt+tab" keys. (Don't forget to press the "Stop" button to release CPU resources).

10) Enjoy chrome browsing and 1080p YouTube videos with sound and no frame drops.

11) OPTIONAL. If you plan to boot into yourSimpleLauncher and be able to launch the scope app any time later:
- install MyAndroidTools,
- disable "GuardServiceReceiver" for the "com.rigol.launcher" application (MyAndroidTools/apps/com.rigol.launcher/see all component info/broadcast receiver/GuardServiceReceiver).
This will prevent FPGA initialization, reduce CPU usage, thus reducing power consumption (from 2.5 A to 1.2 - 1.4 A @12V), chip temperature, and increase device sustainability.

But in this way, you can launch the RIGOL.SCOPE app from the launcher any time later.

[bluesky-ca]

Recently picked up 804 and have been trying to understand better how the OS is configured - thanks to all the great info in this thread getting started was easy.

My two main problems with the scope are:
- fan noise
- boot time

Without voiding the warranty the only solution seems to put something into the blades of the existing fan to stop it from spinning, and place a quiet external fan blowing into the case.   I have not checked yet if the USB B port in the back has power on it - if yes will use that to drive an external fan.

As for the boot time, I have been looking at Android doze mode - the idea is to bring the power down to the point where the scope could remain booted and allow for a quick turn on - some other ideas would be to use a tftp server and do remote boot, but need to get at the bootloader.   Thus far neither sleep or doze has not worked - I think the main reason for the slow boot is the read speed of the SD card - doing a full backup, it shows about 10MB/s.

Now for some info that might be of value to others.  I want the scope to have an accurate time when connected to the network - have been able to force it to use an ntp server:
adb shell su -c 'settings put global ntp_server <IP or name>'

One issue I run into was that the timezone was being reset on each boot - sadly they force the timezone in the startup script:
adb shell
su -
cd /rigol/shell; cp start_rigol_app.sh start_rigol_app.sh.orig
sed -i 's?setprop persist.sys.timezone Asia/Shanghai?setprop persist.sys.timezone America/New_York?' start_rigol_app.sh

Given the update .GEL file is just a compressed tar, it should be possible to update the script before the update is run.   Adbd is run by default but there is a currently commented out line in start_rigol_app.sh that could shut it down - using WinKey-N combination scroll down to About and click 7 times to enable the standard Android Developer menu.

[Fungus]

Now for some info that might be of value to others.  I want the scope to have an accurate time when connected to the network - have been able to force it to use an ntp server:

ntp works out of the box.

[ebastler]

My two main problems with the scope are:
- fan noise
- boot time

I'm afraid the boot time is par for the course these days; some other scopes are worse. That's technical progress -- a proper OS booting up for you... 

I have not checked yet if the USB B port in the back has power on it - if yes will use that to drive an external fan.

I don't think any USB Device port is supposed to supply power. The USB Host (PC etc.) provides the power; if the Device were to try the same, two sources would be fighting it out.

[bluesky-ca]

Now for some info that might be of value to others.  I want the scope to have an accurate time when connected to the network - have been able to force it to use an ntp server:

ntp works out of the box.

In my case all the hardware is behind a firewall - ntp is provided by local hosts, all Internet connections go through a proxy.   Before I made the change I did not check which ntp servers they were using as the default.

[bluesky-ca]

My two main problems with the scope are:
- fan noise
- boot time

I'm afraid the boot time is par for the course these days; some other scopes are worse. That's technical progress -- a proper OS booting up for you... 

I have not checked yet if the USB B port in the back has power on it - if yes will use that to drive an external fan.

I don't think any USB Device port is supposed to supply power. The USB Host (PC etc.) provides the power; if the Device were to try the same, two sources would be fighting it out.

Maybe I am not understanding but if I plug a USB drive or a kbd  dongle into the front port, the port will provide the power to it - what I am not sure is what type of port the back USB B port is - I need to look at the manual.   

Forgetting the issue of where the power for the fan would come from, has anybody stopped the internal fan and used an external one ( without opening the case ), or are people just adding an external fan and both are running ?   Is the internal fan PWM or just runs at the same speed all the time - thanks.

[ebastler]

Maybe I am not understanding but if I plug a USB drive or a kbd  dongle into the front port, the port will provide the power to it - what I am not sure is what type of port the back USB B port is - I need to look at the manual.   

The port in the front is a USB Host port. You connect USB Devices to it (memory stick, mouse etc.), and they are controlled by and powered from the Host, i.e. from the oscilloscope.

The port in the back is a USB Device port. You connect a USB Host to it (your PC), and the Host provides power -- although the Rigol scope, acting as a USB Device, does not use that power. But it can't provide power itself since that would clash with the power supplied by the Host.

[Fungus]

Forgetting the issue of where the power for the fan would come from, has anybody stopped the internal fan and used an external one ( without opening the case )

You mean by poking a stick through the bars? I don't think anybody's tried that yet, no.

[bluesky-ca]

Maybe I am not understanding but if I plug a USB drive or a kbd  dongle into the front port, the port will provide the power to it - what I am not sure is what type of port the back USB B port is - I need to look at the manual.   

The port in the front is a USB Host port. You connect USB Devices to it (memory stick, mouse etc.), and they are controlled by and powered from the Host, i.e. from the oscilloscope.

The port in the back is a USB Device port. You connect a USB Host to it (your PC), and the Host provides power -- although the Rigol scope, acting as a USB Device, does not use that power. But it can't provide power itself since that would clash with the power supplied by the Host.

I suspected that it was the case - I guess I can use a USB C splitter, and get the power from there, or just have a dedicated power brick.   Most of the time the scope will stay in one place possibly mounted on a VESA mount.   The part I am not sure about is stopping the internal fan by 'force'  with a piece of wood dowel by poking it through one of the holes in the back.

[ebastler]

The part I am not sure about is stopping the internal fan by 'force'  with a piece of wood dowel by poking it through one of the holes in the back.

It does sound a bit crude, and might cause higher-than-intended current through that fan. Have you tried "passive" solutions? Try guiding the sound by placing some barriers above and/or on the sides behind the scope, maybe an air duct made of styrofoam or such, so less direct sound reaches your ears. If there's a wall behind the scope, that might also reflect the fan noise, and putting some dampening material there might help. All without blocking the airflow, of course.

[Fungus]

Stopping that fan will also block airflow to the hottest part of the heatsink.

Much better to learn how to remove warranty void stickers without breaking them. 

[Martin72]

Without voiding the warranty the only solution seems to put something into the blades of the existing fan to stop it from spinning, and place a quiet external fan blowing into the case.

That´s a really bad idea...
As ebastler already mentioned, the current can increase excessively and thus damage not only the fan but also other components - and then the warranty may also be invalidated.
In general, when modifying/replacing fans, it is important to bear in mind that the original fan was included in the thermal load calculations during development.
Now the internal fan sits directly on the large heat sink and blows through its fins.
If you now want to go along and have a fan blow into the housing from the outside, it has to be "stronger", which could ruin the hope of making the device quieter.
If you ignore this in order to simply make it quieter, the power could be too low and the device could heat up more, which could lead to malfunctions or deviations from the measurement tolerances.
The external fan must then also be attached in such a way that the air flow can enter the housing as unhindered as possible.
This means screwing or gluing and then the warranty is also void.
I would think about it if I were you and weigh up the pros and cons.

[bluesky-ca]

Stopping that fan will also block airflow to the hottest part of the heatsink.

Much better to learn how to remove warranty void stickers without breaking them. 

That  or if they made the fan PWM - an external fan would be able to make it run at a much lower speed.   I have a second fan just sitting behind and the Board test shows about 43C CPU and 39C Ambient temps.

All my current computers are either all-in-one with no fan or NUC like boxes - I am not a fan of any noise ( pun not intended ).   I watched Dave's fan video while back so I don't recall if he mentioned if it was PWM or not. 

[bluesky-ca]

Without voiding the warranty the only solution seems to put something into the blades of the existing fan to stop it from spinning, and place a quiet external fan blowing into the case.

That´s a really bad idea...
As ebastler already mentioned, the current can increase excessively and thus damage not only the fan but also other components - and then the warranty may also be invalidated.
In general, when modifying/replacing fans, it is important to bear in mind that the original fan was included in the thermal load calculations during development.
Now the internal fan sits directly on the large heat sink and blows through its fins.
If you now want to go along and have a fan blow into the housing from the outside, it has to be "stronger", which could ruin the hope of making the device quieter.
If you ignore this in order to simply make it quieter, the power could be too low and the device could heat up more, which could lead to malfunctions or deviations from the measurement tolerances.
The external fan must then also be attached in such a way that the air flow can enter the housing as unhindered as possible.
This means screwing or gluing and then the warranty is also void.
I would think about it if I were you and weigh up the pros and cons.

I agree - on the plus side we do have built in temp. sensors and it is easy to verify any results.  Without those sensors it would be a lot more difficult to know if there is any negative impact.  I am sure we all have seen fans that have been on for years full of dust that have stopped working -  to be honest I have never measured small 12V fans - not sure if  the stall current applies here.

[Fungus]

The external fan must then also be attached in such a way that the air flow can enter the housing as unhindered as possible.
This means screwing or gluing and then the warranty is also void.

There's 4 screw holes on the back for mounting things.

I was thinking of 3D printing an adapter for a 90mm fan.

[Martin72]

There's 4 screw holes on the back for mounting things.

That's right, I hadn't thought about it.

I was thinking of 3D printing an adapter for a 90mm fan.

I might find the fan a bit annoying, but it's rarely so quiet here that it's noticeable.

[Mechatrommer]

there was a time i'm stupid with electronics, but blocking fan with a stick is not one of it. read the manual, if you poke around what not a normal users do, you void the warranty. asking for warranty because of what you did and saying you did nothing is cheating. better learn proper engineering.

[enson72]

I did so and forgot. Fixed it on the ties. Silence now. Temperatures are normal. It's an old fan. I checked on it. I ordered a new one, I'm waiting. 92mm

[bluesky-ca]

Has anybody rebooted into the bootloader or the recovery using adb reboot bootloader or adb reboot recovery ?  I recall a post from a person that tried to run fsck and in the end sadly had to void the warranty to resolve it - at least for now I want to play safe.

I want to try to boot it from a USB drive to see if it can boot faster - it would be nice to see how fast it can be.    I was thinking that network boot might be faster, but ram to ram copy over the network is not very fast ( at least using adb ):

adb shell 'dd bs=1024 count=100000 if=/dev/zero' | dd status=progress  > /dev/null
95878656 bytes (96 MB, 91 MiB) copied, 10 s, 9.6 MB/s

I also tried using ssh pipe from the scope to a Linux box - got about 11.7 MB/s - hope nobody is tempted to make this into a NAS box 

I plan to do some more reading on sleep and doze modes in Android 7 - would be nice if they implemented that at the factory and give it as an option.  Pressing the power button could have an option of sleep or off.

[bluesky-ca]

I did so and forgot. Fixed it on the ties. Silence now. Temperatures are normal. It's an old fan. I checked on it. I ordered a new one, I'm waiting. 92mm

Just to make sure I understand - you did or did not stop the built in fan ?  If yes what method did you use ?

[enson72]

I did so and forgot. Fixed it on the ties. Silence now. Temperatures are normal. It's an old fan. I checked on it. I ordered a new one, I'm waiting. 92mm

Just to make sure I understand - you did or did not stop the built in fan ?  If yes what method did you use ?

I opened the case, removed the fan, connected the external one. If you put 120mm, it will rest against the table. That's why I chose 92. I bought from the Chinese, so I don't really care about the warranty.

[bluesky-ca]

Thanks for the update - I suspect with a good quality fan one might get better thermals compared to the built in one.   I believe most fans operate better in push mode compared to the pull, the only limitation here is the total cross area of the case holes over the external fan.

[enson72]

Thanks for the update - I suspect with a good quality fan one might get better thermals compared to the built in one.   I believe most fans operate better in push mode compared to the pull, the only limitation here is the total cross area of the case holes over the external fan.

I think any fan will do. With this size of the blades, it will have a larger air flow than the built-in one. They installed the wrong type of fan. It needs a turbine like this. And the one they put up, the air flow is directed to ...))

[Fungus]

I'm thinking about one of these... I use them in all my PC builds these days. They're completely silent.



I/m gonna 3D print an adapter adapter to attach it to the VESA holes.

[enson72]

There was no bequiet or Noctua on sale. I ordered it easier. This is not a computer that I almost never turn off. I think it doesn't make much sense to strive to put a long-lasting quiet cooler. And why complicate it with an adapter? Plastic ties - 5 minutes and you're done.