Cheap Aneng meter calibration/reset procedure?

[mtdoc]

In my quest to find some cheap but functional DMMs for my kid's school maker space, I purchased an Aneng AN8001 (safety Nazis relax - these will be for battery powered 9V or less circuits only).   

It arrived non-funcitonal:  When turned on it displays "CAL" then runs through what looks like a bunch of hex characters before finally settling on a display of  "Err0".   It looks to me like it is stuck in a calibration routine. Inspection of the PCB shows no obvious manufacturing defects.

From reading prior threads, it looks like all these cheap Aneng meters use the DTM0660 chip.

Does anyone have any info or links to documentation on the calibration or reset procedure for one of these meters?  Other ideas?  A search has turned up zilch for me..

[colorado.rob]

How much did you pay for the meter?  How much is your time worth?  How much money will you be saving by fixing this meter?

[mtdoc]

I paid nothing for it. I requested a refund on return. Got the refund and told not to return it.  I just hate to throw away a functional meter if all I need to fix it is the proper sequence of button presses. The cal or reset procedure for these meters would be worthwhile info in any case. I also purchased a functioning AN8008.

[Mark Hennessy]

You can find a translation of the datasheet here:

http://www.kerrywong.com/2016/04/03/dtm0660-datasheet-translated/

The calibration procedure - such that it is - is at the end. Prior to that, on page 7, is some detail about the power-up procedure, which implies that it might be an EEPROM fault?

Hope this helps, but if it doesn't, I guess it's still nice to hold on to for spare parts if you were to buy some more of these for the maker space?

[floobydust]

Here is the google translated CAL procedure for the DM0660 (Dream Tech firmware) from the datasheet. It looks like you can skip ranges etc. I did not care much for Kerry's translations.
On Russian forums, a guy has written software to do the CAL, but I have not looked for it yet.

Code: [Select]

12 Calibration process method
The following description of the calibration flow is based on the wiring diagram of this manual. (See circuit diagram).
Button function assignment during calibration: SELECT: Skip / function selection; HOLD: minus (-); The rest of the keys: plus (+)

12.1 Enter calibration mode
{J8 is disable EEPROM write-protect WP & MCU into CAL mode}
Short J8, boot into calibration mode. (Function switch must be placed in the resistance (ohms) mode, and remove the DMM input probes)

12.1.1 Self-Check
After checking the IC internal circuit, CAL, LCD display, ADC code value, if there is an error then display Err0 ~ 4, then shut down after the measurement with the measured voltage divider whether the connection is short circuit, open circuit, the size of the resistance is correct etc.
After the completion of self-check, and then re-boot, start the calibration process, self-test is completed automatically save the relevant parameters to EEPROM, buzzer BEEP sounded to indicate save complete. If it has already been detected, press the SELECT key to skip this check.

12.1.2

12.2 Voltage correction (DC 500.0mV)
Function switch in DC millivolts.
The voltage output of the calibrator is inserted into the Vinput, the negative terminal is inserted into COMMON, the calibrator output set to DC500.0mV, press +/- to adjust display to 500.0mV. If you have already adjusted, press the SELECT button to skip this step.
Voltage output value that can be used for correction: 100mV ~ 500mV (integer multiples of 100mV), the recommended value is 500.0mV. Adjust the display value to match.

The output of the instrument can be the same, the following steps are similar.

12.3 Resistance Correction (50.00Kohm)
Function switch in Resistance ohms.
Calibrator output 50.00Kohm, press +/- to adjust the display to 50.00 Kohm, If you have already adjusted, press SELECT key to skip this adjustment.
Values that can be used for the correction of the output value: 10Kohm ~ 50Kohm (integer multiples of 10Kohm). The recommended value is 50.00Kohm.

12.4 Capacitance correction (500.0nF, 50.00uF)
Rotary switch set to capacitance position.
Calibrator output 500.0nF, wait for the display is stable, press +/- to adjust to 500.0 nF; Value used can be: 200nF ~ 600nF (100nF integer times), the recommended value of 500.0nF.
Calibrator output 50.00uF, wait for the display is stable, press +/- to adjust the display to 50.00uF. If it has been adjusted, press SELECT to skip this adjustment.
The output value that can be used for correction: 20uF to 60uF (integer multiples of 10uF), the recommended value is 50.00uF.
Note: The capacitor cal needs to adjust the above two points, directly output the corresponding range capacitor value, the program will automatically switch the range.
{EEPROM contains the zero correction stray capacitance value, edit that there}

12.5 Ambient Temperature correction (input actual ambient temperature) {DMM cold junction temp}
Function switch in Temperature.
LCD display default value of 25C or the last adjustment of the ambient temperature (non-current temperature) according to the environment at the time of calibration.
Temperature, press +/- to adjust to the ambient temperature (adjustable range 0 ~ 50C).
Note: If you do not adjust the LCD and the default display temperature is the current ambient temperature, at this time need to press at least +/-
The whole time, if the previous adjustment does not need to adjust again, press SELECT skip.

12.6 DC Current calibration (DC 500.0uA, 50.00mA, 5.000A ranges)
Rotary switch set to DCuA / mA / A for adjustment.
The correct current output of the calibrator is connected to the corresponding input, the negative terminal is connected with the COMMON port, and the DC current DC 500.0uA / 50.00mA / 5.000A, press +/- to adjust the corresponding range.
Can be used to correct the output value:
uA: 100uA ~ 500uA (integer multiples of 100uA), the recommended value is 500.0uA
mA: 10mA ~ 50mA (integer multiples of 10mA), the recommended value is 50.00mA
A:  1A ~ 5A (integer multiples of 1A), the recommended value is 5.000A

Note: The basis of current measurement is the {shunt} voltage, so need to adjust the voltage and then adjust the current, the following current clamp calibration is similar.
{I think that means do not overload or clip the A/D on one range, compared to others as this makes a CAL error condition}

12.7 AC Current clamp calibration
Rotary switch to current clamp function, and the appropriate current can be input according to the range. Adjust the display to the standard output value.
It is recommended to output AC signal 60Hz adjustment, the range output correction value is as follows:
6.000A: 1A ~ 5A (integer multiple of 1A), the recommended value is 5.000A
6.000A / 60.00A, 60.00A / 600.0A, 60.00A, 600.0A: 10A ~ 50A (integer multiples of 10A), the recommended value is 50.00A
600.0A / 6000A, 6000A: 100A ~ 500A (100A integer times), the recommended value of 500.0A;

Note: 1. Individual range in the correction can automatically shift to a small level range, easy to output a small current to correct. Such as school
The positive 6000A file will be measured according to the measured value between 600.0A / 6000A automatic shift, then the output can be adjusted to 500.0A,
Another example is 6.000A file will automatically switch between 600.0mA / 6.000A, can directly output 5.000A current to adjust.
2. Clamp meter current before the calibration should ensure that the full-scale output signal is about 600mV (corresponding to 6000count),
Do not deviate too much, the signal may cause excessive overflow, the signal is too small may cause the resolution is not enough.

12.8 Voltage range calibration
Rotary switch set to DC volts. If the range is set to: DC600mV / 6V / 60V / 600V / 1000V,
It is recommended to inject calibration values of: DC500mV / 5V / 50V / 500V / 1000V, can also set the appropriate parameters for other values.
Press the +/- to adjust the display to the standard output value, you can calibrate the current range.

Note:
1. After the power-on self-test step (12.1) is completed, you can also go directly to the corresponding function to adjust, if the rotary switch is not changed
(PT2.7 ~ 2.4), short-press the Select button, you can ignore the current adjustment, jump to the next adjustment. Default tone
The whole is 12.2 voltage, 12.3 resistance, 12.4 capacitance, 12.5 temperature, and can be in the default resistance function finished
Into the adjustment without having to switch the transfer to the corresponding function.

2. During the adjustment process, after entering the standard signal, wait for the display to stabilize and then press the +/- key to adjust. Avoid output beyond {A/D overload}
Allows the range of signals.

3. The voltage adjustment error will affect the current adjustment, [b]if the voltage readjusted, the current also need to re-adjust. ***[/b]

4. Corrective process of the function of the file is not right, the signal short circuit, open circuit or signal instability will make the adjustment error or
So that the error becomes larger. Adjust the data if the deviation tolerance (+/- 80%), and LCD display the most significant digits greater than 6 or display
"OL" press the +/- key will not respond to the operation, the buzzer no sound. The operation is normal and the correction data is correctly written to EEPROM after the beep
The BEEP sounded, the data can change normally but the buzzer does not sound indicating that the data is not properly saved, please re-adjust one Times.
If still invalid, please check the EEPROM connections, and that J8 jumper is shorted.
5. Please do not adjust the data other than the recommended value.
6. After calibration is complete, make sure that the J8 CAL jumper is disconnected and restart after power-up.


edit: tried to correct Engrish

[hugatry]

Check if J1 is populated/shorted. Calibration process will start when the meter is being turned on with J1/JP2 shorted. Err0 will be shown when calibration process hasn't been started in the resistance mode.

[mtdoc]

Thanks all for the info.

Still no joy. J1 was not shorted. I tried shorting it and seeing if i could re initialize a calibration routine starting in resistance mode, but it's still ends up back at ErrO. It's not clear from the documents exactly how to step through the cal procedure in any case.

I likely will just end up using this as a parts donor.

[Fungus]

I likely will just end up using this as a parts donor.

If you can write to the EEPROM then just rewrite the calibration values for the range you want to fix.

[Gandalf_Sr]

I'm going to try to calibrate my AN8008 using this process.  The instructions above seem unclear about how to save settings.  Maybe someone here knows the answer to these questions?
1. Start up with the internal link shorted and then turn rotary selector from OFF to RESISTANCE and self check will be performed - is this correct? 
2. Then what, do you do?  Do you just change the rotary selector to the units you want to calibrate (I just want to calibrate uA, mA, A), provide the appropriate input, use the buttons to - / + to match the value applied - but then what?  Is there a save button or something?

Thanks in advance

[riccardo.pittini]

Has anyone managed to re-calibrate an AN8008 or an AN8009?

I need to re-calibrate the current measurement. I managed to enter in a sort of menu, but it's missing the current settings... I can only play around with voltages, capacitances and temperatures...

[In Vacuo Veritas]

These things are awful. Calibrate them by throwing them into e-waste. Even when "working" they don't.

[001]

These things are awful. Calibrate them by throwing them into e-waste. Even when "working" they don't.

Why? This multimeter family looks FAR good when older crappies
program calibration and quick autorange is good

[JohnPen]

I agree with 001 they are not awful.  I have 2 Anengs an 8008 and 870 both are very much in spec on all ranges.  Providing you don't consider using them for high voltages/currents  they work very well for typical hobbyist use which tends to be less than 50v and up to 2 amps.  If you work on the high voltage/current stuff  you need something better for the safety angle.  Mechanically they may not last so long as a higher quality meter but as been stated before you get what you pay for.

[GreyWoolfe]

I agree with 001 they are not awful.  I have 2 Anengs an 8008 and 870 both are very much in spec on all ranges.  Providing you don't consider using them for high voltages/currents  they work very well for typical hobbyist use which tends to be less than 50v and up to 2 amps.  If you work on the high voltage/current stuff  you need something better for the safety angle.  Mechanically they may not last so long as a higher quality meter but as been stated before you get what you pay for.

+1  I have an 8008 and 8009 that I did the mods to.  More than accurate for my needs.  Fluke 27/FM for mains.

[riccardo.pittini]

It it not off by 1-3digits, or by 1% but, by 16% ==> Hence re-calibration needed 

[001]

It it not off by 1-3digits, or by 1% but, by 16% ==> Hence re-calibration needed 

  You simply write coefficients to eprom once

[riccardo.pittini]

No one has more details on the calibration procedure?

I used the calibration (jumper inside the multimeter) but the letters shown on the display do not mean much without a step-by-step or a menu thing

If we manage to sort the calibration thing I have a good mod to make it more safe (it would use 5x20mm HRC fuses )

I would try to write the eeprom, but need the right addresses for the ranges and values.

[Gandalf_Sr]

A bit late but, here's the procedure I used.