Electronics > Repair
Voltcraft DSO 1202D goes crazy right after a few seconds from booting
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rugo100:
Hi,
my Voltcraft DSO1202D after a few years fine working yesterday went 'crazy' when I was checking a PWM circuit prototype.
Since that time when I switch it ON it is booting well and seems to be functioning well but after 10-15 seconds normal work it starts 'hanging', no response for button pressing it starts itself to do different things randomly (like somebody would pushing buttons randomly).
So, it is totally useless now.
I would very grateful if somebody would give me idea what the problem can be and what would possible to do to repair it.
Thank you.

I already have tried to do system recovery without success(ON-OFF and ON again)
rugo100:
I had more time so I made some research on the behavior of my 1202D.

power ON is OK
booting, Voltcraft logo appears
then scope usual screen appear
CH1 MENU, MATH Menu,  CH2 MENU, AUTO SET and RUN/STOP lit but no response for single pus on buttons or selecting a function.
Seems to be the device hangs.
Although it does not work but a bit of life is in it (behind the scenes)
E.g. if I push a function button and keep it a bit longer time the corresponding function screen appears.
Also if I touch nothing osmetimes the device changes screen/function on its own.

Another interesting thing is if  I connect a memory stick the system is recognise it, the disk icon appears on the top of the screen and even I was able to use the 'Update' menu of 'UTILITY' and I have successfully updated the firmware.
Unfortunately after the update then reboot the device behavior is the same as I described above.

Another thing what is working that is the boot menu.
With the booting cycle(ON/OF then ON again) the system recovery menu appears and I can start the system recovery function.
It is finishing well but unfortunately the device behavior is same as before.

like the next step I wanted to connect to the device on UART to see if I can access the operating system or not.
To do this was needed to find UART RX/TX pin inside the device. After a while I found them. See the attached picture.
I have connected an USB-Serial converter then via a terminal emulator was possible to access the system (connection speed 115200bps)
eg unix LS command is OK (see picture #ls)
See terminal screen after booting the scope (see attached)
So operating system on the device seems to be operational.

At this point if I use a function or menu button (push shortly) nothing happen on the terminal but if the push it longer (2-3 secs) some corresponding sequence appears on the screen.

Eg if I push CH1 MENU button shortly noting can seen, but If I keep it pushed longer then on terminal I can see this:

"t_unscan_wave_vertic_operate:ch0:5, 5
factor:chid0, vb:5, pos:0, factor:1.088000
Disp_SyncChOnOff:in
yt_unscan_wave_vertic_operate:ch0:5, 5
factor:chid0, vb:5, pos:0, factor:1.088000
Disp_SyncChOnOff:in
yt_unscan_wave_vertic_operate:ch0:5, 5
factor:chid0, vb:5, pos:0, factor:1.088000
Disp_SyncChOnOff:in
yt_unscan_wave_vertic_operate:ch0:5, 5"

Well, based on above finding I think my scope is not totally dead, but unfortunately I do not know what can/should I do with it to get back a functional device.
Is the problem whether hardware or software related?

If somebody has idea please tell me.

Thank you
Fenstergucker:
I assume your Voltcraft DSO1202D is from Hantek. Does it have a battery for the RTC?

I have a Hantek DSO1202B handheld that no longer has a Li-Ion battery and no battery for the RTC. When I switch it on with the power supply, it behaves exactly as you described.
But if I set the time and restart it, it works normally again. Setting the time is sometimes difficult because the keys play crazy.

Peter
coromonadalix:
you see a coin cell holder in the op pictures ...  near the buzzer
rugo100:
yes, there is a 3 volt battery in it.
It was almost totally empty, 0.xx volt
I have replaced it with a new one, but since the buttons are 'crazy' I could not set the time.
Now I go and try to set it.

Thank you
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