Aneng AN8008 continuity dysfunction

[mosafet]

It seems the continuity test mode on my AN8008 has something wrong with it. When I switch to continuity mode there is a longer than normal beep which is the sign it's not going to work correctly. The meter can sit with nothing connected to it and it will randomly beep as if continuity was established. Also it often doesn't register continuity at all.

Occasionally a full battery disconnect will make it start working normally for a while but the dysfunction always comes back.

Before digging in to it I just want to check to see if someone has seen this before and come up with a fix. Otherwise I'm going to have to trace the circuit and look for broken stuff. Searching has not yielded any information on the topic so far.

Thanks

[KungFuJosh]

I recently bought this meter to test the continuity performance as it has been mentioned as a good choice. It's okay when it works, but it's nothing special. The Uni-T UT123T was much better. Sorry, I know that's not too helpful here.

You could try opening it up and cleaning it. Look for anything that looks sad. 😉

[Doctorandus_P]

I bought the AND8008 meters when everybody was astounded about these things. It has some nice features, such as measuring very small voltages.
Unfortunately the thing is utter garbage.

It has horrible non replaceable fuses, I fixed that by putting in a 20 x 5 fuse holder.
In some modes, when you are measuring small voltage (such as 0.002) then the display just jumps to 0.000 (Yeah, look mam, the display is always zero when the leads are open).

I also bought a lot of presumably 1% THT resistors. I read some bad stories of these being fake sometimes, so I wanted to check their tolerance. When measuring with the AND8008 some of them seemed a few percent off, so I was ready to throw the batch of resistors in the garbage. But then I noticed the display of the AN8008 was not giving a stable measurement either. So I used a real meter (a Wavetek Meterman 35XP I bought second hand for EUR 25) and all the resistors measured OK. Then I went back to the AN8008 and fiddled a bit with the rotary knob, and suddenly the measurements stopped wobbling, and then the resistors measured OK too. So the contacts of the rotary knob are not reliable in this meter. Note this was a meter just a month or so old. As a result, I bought a Brymen 869s, and put the aneng garbage at the bottom of some drawer. I never used them after that initial test.

So in short, if you want to keep on messin' with the AN8008 and it does not work properly, fiddle a bit with the rotary knob. Some of the meters have a bit of (special, (silicone?)) grease on the contacts. This may extend the lifetime of the rotary contacts, and also prevent oxidation.

[Fungus]

Sounds like the sort of thing that could be caused by a bad contact on the selector. Try cleaning that.

Otherwise I'm going to have to trace the circuit and look for broken stuff.

If you open it up you'll see there's a not a lot to "trace" and what little there is would affect other ranges.

If all the other ranges work then it's either a bad selector or time for the bin.

[Aldo22]

It has horrible non replaceable fuses,

I had no problems buying these small fuses on AE.
The AN8008 works well for me.
You must have had a lot of bad luck.

[floobydust]

It's a $25 multimeter with 9,999 counts - what are people expecting? I've complained about it in a few threads but really, it's what you pay.

The rotary switch uses cheap metals - if the leafs were not some copper and slag metal, Brymen seems to use gold plating, it would be better.
Applying a PPE contact cleaner stops a lot of the problems with the contacts oxidizing. Originally it is a swath of mineral oil there.

You want it small, compact but big fuses? No, it's not a TARDIS. They could stuff 5x20mm in there but the design was in a hurry.

It has a firmware bug on ACV, ADC noise can be lessened and autoranging speeded up by adding decent bulk capacitance, and the deadband at +/- a few uV to mask ADC noise is known.

[KungFuJosh]

100%! You get what you pay for...even though the UT123T costs less and worked better for what I tested it with. 😉

Also, precision resistors can't be accurately measured in a meaningful way on a device rated lower than the resistors are.

[Aldo22]

100%! You get what you pay for...even though the UT123T costs less and worked better for what I tested it with. 😉

You can't really compare them.
The UT123 is absolutely brilliant in continuity measurement, but otherwise...
It can't measure current and has no mV range.
No, apart from continuity, the AN8008 is far superior.

[tooki]

I had no problems buying these small fuses on AE.

Can you share a source?

I’ve been looking for years, but have never found them. Assuming I find the right size, they’re either not ceramic, or they don’t have 200mA available, or both, or they have leads, or the picture shows the right ones, but the offer is then for a completely different size.


(I haven’t blown my AN8008’s fuse, but I’d like to have a spare around.)

[Aldo22]

Can you share a source?

Hmm, it does seem to have become difficult.
I had mine from RICHMETERS Official Store on AE, but they no longer have them.
You can get some in South Africa: https://www.diyelectronics.co.za/store/fuses/3795-2-pack-replacement-ceramic-fuses-for-aneng-an8008-multimeter.html
In terms of size, these might work if you cut off the wire, idk:
https://de.aliexpress.com/item/1005008281723048.html

[tooki]

In terms of size, these might work if you cut off the wire, idk:
https://de.aliexpress.com/item/1005008281723048.html

Remember how I said “or they don’t have 200mA available”? Look at that listing again.

[Aldo22]

Remember how I said “or they don’t have 200mA available”? Look at that listing again.

Yes, that's true. The ones from South Africa are also specified with 0.6A.
I only have 2x200mA here too, the others are 10A.
Then you just have to be careful. 

[stj]

put dialectric grease on the switch pads.
do that for any meter that doesnt come pre-greased.

[floobydust]

I've tried many lubes on the AN8008 rotary switch. The problem is the rotor leafs are made of some impure copper that oxidizes really easily.
Factory lube is mineral oil.
Best in multimeters I find is DeOxit F5, it has PPE.  https://www.eevblog.com/forum/beginners/multimeter-rotary-switch-contacts/msg5163279/#msg5163279
Fluke was using Nye Lubricants 813S silicone grease which is thickened with PTFE.