repairing the dso nano v2? Need some advice

Products & Technology DSO Nano
#1

Hi there,

My dso nano v2 was installed in my cars dash for almost 2 years now, connected to the onboard computer for power supply and the test leads connected to the backup batteries (camping and solar panel stuff) so i could monitor them. Chances are, the potential difference between where the pc got it’s power from and the batteries
was quite high at times
I also often forgot to turn it off and had it run until the battery was empty when the cars systems were powered down.

Now i uninstalled it from the car and it doesn’t seem to work properly anymore:

  • When i want to charge it, i have to connect the - Probe to the Usb - line or the screen will flicker (or rather dim extremely dark) and the battery won’t charge.

  • The signal generator is not functioning.

  • The battery still has good life but the battery symbol still depletes quickly.

  • Measurements are off by a few 100 millivolts (0.2-0.4 i think)

Now i got smd soldering equipment and some (almost none :stuck_out_tongue: ) experience soldering parts into cellphones, so i was thinking about at least attempting to fix it, there isn’t a chance i could afford a new one in the near future and it’s such an useful tool.

Long story short, i want to fix it. But what to replace?

My first guess was to replace the LTC4054 charger controller chip. But what about the signal generator? Some repair tips would be welcome, i’m gonna take it apart anyways :laughing:

#2

Could this be the protection coil L3 is blown?

The signal generator is a GPIO output from the microcontroller buffered by a 74HC125. Maybe just the latter needs replacement.

I guess you have seen in the schematic how the battery voltage is divided and fed to the microcontroller (Vbat). Check those resistors. Or maybe replacing the LTC4054 will fix this as well.

#3

Awesome, thanks for your answer. There are schematics available? I thought only the software part was truly open source.

Where could i find those schematics?

#4

In the wiki, of course!

seeedstudio.com/wiki/DSO_Nano_v2

I am surprised that the wiki is such a well-kept secret. A lot of the requests in the forum would be answered by having a look there. Maybe I should add a sticky post about it.

#5

Don’t always trust the wiki… I’ve learnt that the hard way; now I have a half-working DSO v3 because I trusted what’s written there.