AN8008 US $19, 9999count, 1uV, 0.01uA, 0.01Ohm, 1pF resolution meter

[bobale]

I've just tried removing one of the 10M resistor, and it is not measuring voltage at all. So definitely they are part of a voltage divider.

After mucking about with different resistors, I've managed to get it to show 9.990V on 10V reference, and 4.995V on 5V refence. I don't think I can make it any better, so I'll leave it as is.

[TurboTom]

The failure of your DMM doesn't appear to be related to the 2*5MOhms dropper resistors directly, if so they both would have been charred. It rather looks like the quite high striking voltage of the CCFL inverter just caused an arc to form from the "hot" terminal of the first resistor to ground, resulting in the underlying FR4 to dissociate/carbonize. In order to repair the instrument properly, you would have to grind away all of the affected FR4 so there won't be any bare carbon residues left in this area. Otherwise, there will always be a low(ish) impedance path to ground, making measuring modelstly high voltages VERY dangerous (provided the source is capable of delivering high energy).

[Fungus]

I've just tried removing one of the 10M resistor, and it is not measuring voltage at all. So definitely they are part of a voltage divider.

Yep. Those resistors are the input protection for the voltage range. There's two of them in series to make it tougher. If you remove one then the volts can't get through to get a reading.

After mucking about with different resistors, I've managed to get it to show 9.990V on 10V reference, and 4.995V on 5V refence. I don't think I can make it any better, so I'll leave it as is.

Any high-ish values will do but 10M total is the standard.

[bobale]

Otherwise, there will always be a low(ish) impedance path to ground, making measuring modelstly high voltages VERY dangerous (provided the source is capable of delivering high energy).

I've dug around the board as best as as coud. How high voltages are we talking about? I've tried measuring 230VAC, and it worked fine. Also, just measured input filter cap on switchmode psu (~325VDC), and it was fine. That's the highest voltage I usually measure.

[Fungus]

I've tried measuring 230VAC, and it worked fine. Also, just measured input filter cap on switchmode psu (~325VDC), and it was fine. That's the highest voltage I usually measure.

If you "usually" measure voltages like that then it's time to get a Fluke 101.

[bobale]

Bad choice of words I don't usually measure high voltages, but if I go HV, that's as far as I will go.

[TurboTom]

Just make sure there's no charring left on the PCB. Any amount of carbon deposition will lower the break-down voltage tremendously. This effect is deliberately used on most modern turbine engine spark plugs ("shunted spark plugs") to be able to run the plugs on 2000V exciters instead of the 10+kV required to break down a conventional spark plug, with the accompanying reduced requirements for interconnection, wiring and so on (lower installed weight).

It's impossible to tell at what voltage the "dirty" insulation gap of your DMM will fail, but if you ever use the instrument on mains (I hope only on properly fused indoor circuits) or other similarly elevated voltage / energy circuits, it is reason to worry. Even more so since the AN8008 cannot be considered the most appropriate (read: safe) instrument for this kind of measurement anyway.

[bobale]

Thanks for all the advice, I will definitely take more care next time. I bought it for low voltage use mostly anyway.

[francisroan]

Hello,

This is my first post on the blog (YAY!).
Unfortunately, my Aneng AN8009 has sort of miscalibrated somehow, it was showing values off the usual case and so upon reading few threads(including this one) I came to realize that the meter can be re-calibrated by jumping the J2 pins. Which I did and fiddled around the values. But me being stupid, didn't think of getting an accurate calibration tool( don't have access to one anyway) and made the problem worse. No the meter is pretty much useless as it gives some gibberish value (like 830mV for a 3.86V supply). Even the NCV function doesn't seem to work anymore.

So, basically, I was wondering whether I could flash the EEPROM with the stock calibration value dump? If so, where can I find the dump? I looked everywhere and I couldn't find it. I did look at Kerry D. Wongs blog on extracting the EEPROM dump and I have the necessary stuff to do it as well (Arduino and wires )but there is no EEPROM dump for the AN8009 model. Will the AN8008 work with this?

I just need this working again ASAP. Any help is appreciated

Thanks & Regards

[exe]

stock calibration value dump?

I might be able to do it tomorrow evening, but no promises.

[exe]

Well, I desoldered the prom chip, but I don't know how to read it. I have ch341a programmer and Linux. Any hints? All articles I found so far are about reading spi chips, but the one in the dmm is of i2c type (p24c02a). Should it just work, or I need to provide i2c address to the programmer so it can read the eeprom?

PS This is my programmer: https://www.aliexpress.com/item/32793476447.html?spm=a2g0s.9042311.0.0.27424c4dal4nao .

[indman]

Dump EPROM RM111 this is analog AN8009 

[exe]

Well, I dumped the rom with the command below. I hope it's complete because the tool seems to be hardcoded to dump only 24c32 and 24c64 chips. For some reason the output is 4kb, even though the IC itself is supposed to be 2kb. So, use it at your own risk

Code: [Select]

$ sudo ch341eeprom -d -s 24c32 -r 8008.rom
Wrote [4096] bytes to file [out.rom]                                                 
Released device interface [0]                                                         
libusb: error [do_close] Device handle closed while transfer was still being processed, but the device is still connected as far as we know
libusb: error [do_close] A cancellation hasn't even been scheduled on the transfer for which the device is closing


[boffin]

Well, I dumped the rom with the command below. I hope it's complete because the tool seems to be hardcoded to dump only 24c32 and 24c64 chips. For some reason the output is 4kb, even though the IC itself is supposed to be 2kb. So, use it at your own risk

Code: [Select]

$ sudo ch341eeprom -d -s 24c32 -r 8008.rom
Wrote [4096] bytes to file [out.rom]                                                 
Released device interface [0]                                                         
libusb: error [do_close] Device handle closed while transfer was still being processed, but the device is still connected as far as we know
libusb: error [do_close] A cancellation hasn't even been scheduled on the transfer for which the device is closing

a 24c32 is 32 kbits (hence the 32), or 4kbytes

[andyB2022]

Hi, after modifying with an Arduino "writeByte(I2C_ADDR, 0xAD, (byte) 0x13)", the temperature shown by the meter is 38-40 degrees C even with shorted leads, which is way too high. I've tried a temperature probe from a uni-t and the temperature does rise if I touch it to something hot but it's off with over 15 degrees C. Using the same probe with a "good" meter I get 30C instead of 45C with Aneng.

May it be because I didn't activate Fahrenheit degrees too? (I never use Fahrenheit).

[floobydust]

There's little information about the format of the calibration bytes. I would make sure all 5 bytes are correct.
0BH,0CH 00FAH 环境温度(25.0°C) = Cold junction ambient temperature (25.0°C). "Adjustable range 0~50°C", reading with input jacks shorted.
0DH~0FH 03BE00H 环境温度默认ADC值  "Ambient temperature default ADC value"

Code: [Select]

     0  1  2  3  4  5  6  7  8  9  A  B  C  D  E  F
00: FF FF FF FF FF FF FF FF FF 52 00 FA 00 00 BE 03


[andyB2022]

Yep, I have them exactly like that...

Code: [Select]

FF FF FF FF FF FF FF FF FF 52 0 FA 0 0 BE 3
10 17 F 27 52 3 6E 50 64 4B 3C 3C A FF 40 FF
7 9A D6 81 64 0 96 0 0 80 A4 80 0 80 FB 78
4E 2 9 D3 FA 9 EE FE 9 8B EC 9 C9 19 A 0
0 1 0 1 0 7 98 0 64 0 64 0 64 0 0 0
0 80 0 80 0 80 0 80 0 80 0 80 0 80 0 80
9B 7E EE 7F A 0 EF 2A 0 0 0 0 0 0 0 0
6C 81 0 80 5C 84 E0 7C 18 1 0 0 0 0 0 0
0 0 0 0 0 16 0 10 0 C 0 7 13 1 12 3
0 0 0 0 0 0 0 11 0 D 0 9 15 2 0 4
0 0 0 0 0 0 0 0 0 0 0 A 0 13 0 0
0 0 0 0 0 0 0 0 0 0 0 B 0 0 0 0
D 0 2 10 D 0 3 20 20 0 3 20 20 0 3 10
0 80 0 80 0 80 0 80 41 0 3 5 D 0 2 20
0 80 0 80 0 80 0 80 0 80 0 80 0 80 0 80
0 80 FF FF FF FF FF FF 5A C7 CC F 78 B2 0 0
As someone on the forum experienced same issue Ive found thsee 3 values:

FA 00 C0 CE 03
E6 00 00 BD 03
F0 00 48 CE 03

8008
FA 00 00 BE 03 < this is the default value in the datasheet

FA 00 C0 CE 03 seemd that fixed it. I will try and come with an update.

[andyB2022]

After several attempts I have:

28 Celsius  with  F0 0 48 CE 3
29 Celsius  with  FA 0 C0 CE 3
33 Celsius  with  E6 00 48 CE 3

Any ideea on how to get that 25 Celsius ?

Got it: AA 0 0 BE 3

Previously I've had FA 0 0 BE 3 and 33C, so I've substracted 33 - 8 = 25 => AA in hex. 

[sausagemaster]

Not sure whether this has been mentioned somewhere in this thread, but I discovered a way to disable the auto power-off feature with stock firmware.

1. Switch the meter off.
2. Press and hold the "SEL/HOLD" button.
3. Switch the meter on and release the button once it starts beeping.

If done successfully, it should beep 5 times. It will then also beep twice every 15 minutes - once to give a warning as usual, then again after 1 minute (this is when it would normally power off, but instead it beeps). Really annoying but whatever. Maybe that's why this function is not documented...?

[wasedadoc]

Not sure whether this has been mentioned somewhere in this thread, but I discovered a way to disable the auto power-off feature with stock firmware.

1. Switch the meter off.
2. Press and hold the "SEL/HOLD" button.
3. Switch the meter on and release the button once it starts beeping.

If done successfully, it should beep 5 times. It will then also beep twice every 15 minutes - once to give a warning as usual, then again after 1 minute (this is when it would normally power off, but instead it beeps). Really annoying but whatever. Maybe that's why this function is not documented...?

It is documented.

[sausagemaster]

Not sure whether this has been mentioned somewhere in this thread, but I discovered a way to disable the auto power-off feature with stock firmware.

1. Switch the meter off.
2. Press and hold the "SEL/HOLD" button.
3. Switch the meter on and release the button once it starts beeping.

If done successfully, it should beep 5 times. It will then also beep twice every 15 minutes - once to give a warning as usual, then again after 1 minute (this is when it would normally power off, but instead it beeps). Really annoying but whatever. Maybe that's why this function is not documented...?

It is documented.

Indeed! I was convinced I'd read somewhere that the auto power-off cannot be disabled, but I guess that was regarding the shabby DT9205 which I also own. I would have checked the manual, but as it appears I've lost it

[mwb1100]

I would have checked the manual, but as it appears I've lost it

https://www.mikrocontroller.net/attachment/375155/AN8008.pdf  (all clean from virustotal.com)

[StevenNi]

Has anyone else experienced a similar issue? When I switch to measuring in mV, it starts to rise to 99 mV (in 10 to 15 seconds) and throws an OL error because the maximum is 99 mV. When I short probes, it returns to 0 mV and measures the voltage perfectly. It doesn't matter if probes are inserted into it or without them, it only returns to 0mV when short probes.
What could be the issue since everything works fine with my other multimeters?

[Fungus]

Has anyone else experienced a similar issue? When I switch to measuring in mV, it starts to rise to 99 mV (in 10 to 15 seconds) and throws an OL error because the maximum is 99 mV. When I short probes, it returns to 0 mV and measures the voltage perfectly. It doesn't matter if probes are inserted into it or without them, it only returns to 0mV when short probes.
What could be the issue since everything works fine with my other multimeters?

That's completely normal in mV range.

[smokeless0864]

Hi, 2 questions

Can we access readings in UART?

Can it be powered from li-ion battery 10440, ie 3.7v and a dummy cell?