Does it have the AC measurement bug? If you switch from DC to AC it may show low AC voltage.
Info?
I just connected it to a 5V supply in DC mode then switched to AC. The reading went down to zero (as expected).
I think that's from Joe's video:
https://youtu.be/4PjmFqzlfLc?t=1542
This is why I asked Fungus to repeat the test on the first page. I may be able to shed some light on it or some confusion. If you watch the video you will notice that there is a DC and AC component to the waveform. I have stated many times that the output from this generator is a 220VACrms 60HZ that was full rectified and unfiltered. This normally provides me with a quick check of the AC, DC and AC+DC functions. In this case, the meter can not seem to handle the rectified signal reliably. The 8002 had a similar problem. Both of these meters were damaged far beyond repair however, I did buy a second 8002 for a future video.
I used my arb to get us away from the AC mains so others could perhaps repeat the test in a safe manor. Again I full wave rectified the output of the Arb. Yes, a basic function generator is all you would need. At 400Hz, sine, 10Vrms, full rectified the 8002 will read 10.01VAC. My HP will read 10.002. Switching the 8002 to DC, it reads 20.19 and the HP reads 20.198. Switching back to AC and the 8002 read 10.01. So no problems.
Now lets increase the amplitude to 15VACrms with no other changes. The 8002 reads 15.01AC and the HP reads 15.004. Switch to DC and the 8002 reads 30.62 where the HP reads 30.63. No problem. Now switch the 8002 back to AC and it reads 3.093AC! Of course, the HP still reads 15.004. With the 8002 still in the AC mode, disconnect the leads and reconnect and the meter still reads 3.040. I disconnect again and reconnect, 15.01. Hit and miss.
There are inexpensive meters out there that may have poor quality, may be sensitive to ESD or not very robust but at least they throw up correct numbers with some basic waveforms. Personally even for basic bench hobby work, I have no use for these cheapo meters. When you have to stop and thing under what circumstances is your meter not going to work, what's the point?