FNIRSI DSO TC3 Component Tester, Oscilloscope and Signal Generator

The FNIRSI DSO TC3 Component Tester, Oscilloscope and Signal Generator has many reviews, the majority of which have been very positive. I ordered one from the official FNIRSI Ali Express site but things didn't turn out too well. The unit had two major problems; unstable oscilloscope and the unit giving up completely.

Oscilloscope Mode

Instability in oscilloscope mode. The video below shows the DSOTC3 and the DSO153 measuring the same signal. The DSOTC3 is very unstable in comparison.

FNIRSI said that the DSO TC3 is essentially a component tester, implying that this instability ought to be acceptable. They gave me a partial refund!

Giving Up

After testing components, generating signals and  using the oscilloscope for a few days, the unit failed to turn on. The people at FNIRSI asked me to check the internal battery connection and it's voltage.

Not switching on

Secure battery connection

Battery charged

The battery was securely connected and fully charged and the unit would still not turn on. FNIRSI sent me a replacement.

Component Testing Mode

DSO TC3 shows a 47 ohm resistor as a diode. The same error occurs when testing 5k ohm and 6.8k ohm resistors.

See also  https://www.eevblog.com/forum/testgear/fnirsi-tc3/50/    post by Phil1977

I contacted FNIRSI and they replied:

This may not be a unique issue. You can try testing other resistors to see if the problem persists. If the issue persists, you may need to disassemble the device and inspect the corresponding components.

If the problem is limited to this resistor, it may not be a device issue, or, as you suggest, a firmware issue. I will provide prompt feedback. You can try a resistor of the same resistance value to verify this information.

I did test other resistors and several resistors of the same values; the error still occured with the three values of resistor. I await their reply.