Odd problem with Aneng AN8002

[glarsson]

I bought two AN8002 for use in situations when my expensive meters aren't required or wanted (due to dirt etc).

Both meters were bought from the same seller. One is blue and one is orange.
The odd thing is that the V and mV position has different functions when using the orange button.

Blue meter on V:        DC V, AC V, Hz, %
Orange meter on V:    DC V, AC V

Blue meter on mV:      DC mV, AC mV
Orange meter on mV:  DC mV, AC mV, Hz, %

I guess this means that the contents in the EEPROM is different. But why?

[crazyguy]

I bought two AN8002 for use in situations when my expensive meters aren't required or wanted (due to dirt etc).

Both meters were bought from the same seller. One is blue and one is orange.
The odd thing is that the V and mV position has different functions when using the orange button.

Blue meter on V:        DC V, AC V, Hz, %
Orange meter on V:    DC V, AC V

Blue meter on mV:      DC mV, AC mV
Orange meter on mV:  DC mV, AC mV, Hz, %

I guess this means that the contents in the EEPROM is different. But why?

I don't have this meter, but I think the [Hz, %]  functions only can be selected on AC mV/V/uA/mA/A mode, not on DC mV/V/uA/mA/A mode.
It's works like that on my HoldPeak HP-890CN.

Maybe you can dump the eeprom contents to take a look.

[glarsson]

I don't have this meter, but I think the [Hz, %]  functions only can be selected on AC mV/V/uA/mA/A mode, not on DC mV/V/uA/mA/A mode.

On this meter you select the base function with the rotary switch, e.g. V, mV, A or mA. Then you select DC or AC with the orange button.
For V, mV, A and mA both DC and AC can be selected.
For the orange meter it is also possible to select Hz and % in mV function but not in V function.
For the blue meter it is also possible to select Hz and % in V function but not in mV function.
Neither of the meters allows Hz or % for the A and mA functions.
This does not make sense.

[floobydust]

Expect the EEPROM to have silly contents. It seems these are copied from other multimeters and fudged to work with a particular multimeter PCB and enclosure.
It is puzzling to see clamp-on current meter, hFE, temperature function etc. programmed in the EEPROM but not available due to rotary switch limitations.

The EEPROM allows you to program up to four functions within a single position of the rotary switch.
The SELECT key toggles through them. You also need to switch some hardware for some functions.

Hz/% Duty Cycle needs two dedicated switches from the function switch.
These are shown as "jumpers" J2, J2' in this typical DTM0660 DMM schematic. They bias and connect the DMM IC counter to the input.
J2' seems to select high sensitivity and AC signals. Otherwise (J2' open) unipolar signal with lower sensitivity.
< I think these got confused in china and so two places to do Hz/%DUTY measurement according to labels, even though only one is needed. >

[metrologist]

So which one is better? I got the orange one and that hopefully matches the 8008 when it comes in. I got them for low voltage work so I think I'll be happy with the orange one. I'll have to verify its function...

[glarsson]

So which one is better?

Depends.
The blue can measure frequency on V function.
The orange can measure frequency on mV function.
Both can measure frequency at logic levels on Hz function.

Perhaps the color doesn't matter. It could be random...

[metrologist]

My orange AN8002 has Hz/% on the V setting. I like the feel of this meter in my hand.

[stroma]

I don't think the color matters. My blue AN8002 has Hz/% legend on the V setting, but frequency measurement cannot be selected through "SELECT" button on V settings. Frequency measurement is only available on Hz/% setting.