OSCILOSCOP FNIRSI-1013D defect

[Rollin Hand]

Hello I got one of those 30 mzh scope yesterday after almost 2 months waiting from china.. Is not my main scope I have 2 tek 724d.
The problem is on channel 2 with no signal it shows some garbage on top of the ch2 trace.more visible on the 50 mv sensitivity range,if I put the 1kc test signal it still there on top of the 1kc test signal.
If I move the sensitivity up to 5 volts the garbage almost goes  is barley visible .
By shorting channel 2  on the bnc does not change ,the same with a load of 50 ohms ho change.
Thanks
Rollin Hand

[Shiv]

Does it have signal path compensation?

What kind of noise?
DC offset? AC? All?

[Rollin Hand]

erratic  noise ,the main 2 channel trace stays stable is like when you touch a cabinet  and introduce noise on the scope.
no signal path on this scope it has a calibration ,it pass the calibration.Calibration makes all the relays inside the scope work.

[Shiv]

Look for bad solder joints or bad connector in the only analog line that it have.

I think is a bad contact if fails at touch.

[cliffyk]

At risk of being offensive, it is a cheap toy oscilloscope and while it certainly should meet it's claimed specifications; unfortunately when you buy the cheapest there is, you often get the cheapest there is.

Quality control is not a strong point on any of this cheap Asian crap...

[Dd]

If I remember right I read in a comment under the local 1013D review that one guy has solved shifted DC level readings by cleaning input stages from factory flux residues and proper drying later on. So it might be worth a try.

[Rollin Hand]

Thank you Dd I will try your suggestion.
Rollin

[MadTux]

Seems like the average lifetime of china garbage ;-D

[ynas]

1.5 year-old topic, but the unit I got this week seems to have the same problem. Some combinations of sensitivity (volts/div) and frequency (time/div) seem to be worse than others: just now, 1V/div and 100ns/div was the worst combination - see picture. Looking that at picture you'd think it's a ~200mV noise, but turning the sensitivity to 50mV/div reduces the noise to ~20mV. Almost as if the noise was a fraction of a div, whatever the div unit was. No specific frequency, it can happen with any time/div setting. Sometimes, turning the unit off and on again almost completely clears the noise, then eventually it comes back. Only happens to channel 2 and regardless of probes being attached, which makes me hesitant to believe it is external interference.

What annoyed me the most about this unit though, is the loud humming noise when the screen brightness is reduced. I find 100% brightness a tad too bright (and probably unkind to the battery), but I cannot turn the brightness down as I can't stand the noise.

And I wish it had the feature of summing and subtracting the two channels -- it doesn't.

Those are my complaints, yet I do not regret purchasing it! As an occasional hobbyist and given the low price point, its compact size and built-in battery (that allowed me to directly measure mains just for fun, aided by a couple of resistors to simulate a 100X probe), I am not aware of a better value alternative.