Multimeter or Curate's Egg? All-Sun EM6000 Review & Teardown

[rolycat]

This was bought from Maplin a few years ago for £29.99, (about $50 US). It is a rebadged All-Sun EM6000, currently retailing for around $75. It's a curious mixture of good and bad features which I thought might make an interesting subject for a teardown.

Here is the meter, branded as a "Precision Gold N56FU":



It's a 6000-count instrument with a quoted accuracy of around 0.5%. The blue rubber holster is removable.

A nice large LCD with clear digits, a decent backlight and a bar graph. Less impressive is the substantial voltage displayed with an open input.

Date codes suggest the meter was built in 2008 and measured accuracy on the volts and ohms ranges is still well within spec.

The meter features data logging via a built-in USB interface:


It also has a transistor hFE measurement range, but no onboard sockets. It avoids the complaint of many forum members that this feature compromises safety by utilising a plug-in adapter which doubles as a thermocouple input socket:


The tilting bail is fairly substantial and works with or without the rubber holster, and the battery compartment is readily accessible via a twist lock door without removing the holster:



Here is the circuit board:


Impressive large HRC fuses with 80kA breaking capacity on both ranges. Substantial traces with decent creepage distances. And rather shoddy split input jacks.

There is a 1N4007 diode bridge on the mA/uA current range, and two PTCs in series on the voltage input. But no MOVs.

Main processor is a Fortune FS9922-DMM4, also used on Uni-T's UT61 meters among many others. The true RMS converter is an AD737, and the board also has a TI TLC2252 rail-to-rail op-amp.

The two battery contact pads in the centre of the board connect to spring terminals on the rear half of the case, and a large spring contacts the case shielding:

The case is fairly sturdy, if a little cheap-feeling, with blast protection ridges at the join.

The USB input is quite interesting:

Optically isolated and contained in its own little transparent case.

The case contains a small board with a Silicon Labs CP210x USB to UART bridge driver fed by a photodiode:


This is the other side of the PCB:

No components apart from the LCD and switch connections.

All in all it offers some interesting design features and a wealth of capability, and there are many more expensive meters with inferior safety. But the lack of MOVs and the cheap input jacks let it down somewhat.

[ConKbot]

I cringed when I saw a USB port on something branded "Precision Gold"  But their isolation solution doesn't look horrible Input voltage protection looks a little light, but at least they are only claiming cat III 600V instead of catIV 600V/catIII 1kV

[Wytnucls]

Not a bad little meter for someone on a budget, even if perhaps crudely made in some areas.
Fair amount of features for the price, offering USB datalogging with half-decent software. Main drawback is the narrow true RMS bandwidth of 400Hz.

Should be fairly safe on mains, being rated as CAT III 600V, with a GS/TUV listing.
http://www.certipedia.com/search?utf8=%E2%9C%93&locale=en&q=em6000

http://www.all-sun.com/en/d.aspx?pht=821

[retiredcaps]

Is that a giant solder ring crack on the uA/mA input jack (front side) or something else?

Thanks for sharing pictures of this meter! 

[rolycat]

Is that a giant solder ring crack on the uA/mA input jack (front side) or something else?

Just an artefact of my poor photography, I suspect:

[Lightages]

That was not a bad buy at all at $50. I can only find it for around $90 online now. At that price it is not as good a deal but still not a bad meter overall.

[rolycat]

That was not a bad buy at all at $50. I can only find it for around $90 online now. At that price it is not as good a deal but still not a bad meter overall.

It appears to be available here for 56.70 Euros, which is about $62 (plus tax).

[ProBang2]

Or here, rebadged as "McCheck DM-303": https://www.electrobi.de/Werkstatt/Multimeter/Digital-Multimeter/Digitalmultimeter-McCheck-DM-303-schwarz-mit-blauem-Holster-3-5-6-stellig-mit-analoger-Balkenanze.html

Pricepoint: 38,72€ (incl. VAT) + shipping

[rolycat]

Or here, rebadged as "McCheck DM-303": https://www.electrobi.de/Werkstatt/Multimeter/Digital-Multimeter/Digitalmultimeter-McCheck-DM-303-schwarz-mit-blauem-Holster-3-5-6-stellig-mit-analoger-Balkenanze.html

Pricepoint: 38,72€ (incl. VAT) + shipping

Remarkable. At that price it really is a great deal.

[Lightages]

I just looked up "curate's egg". Could you have picked a more obscure reference for those not on the British Isles?  and a religious one at that!

I would say for that price in Germany, it is a real good buy.

[flapjackboy]

Aww, man. Got this exact same meter about 10 years ago and it has served me really well until just the other day, when it died on me after it fell off the workbench. 

Opened it up and found that one of the fuses had blown, but the fuses they use in it are rarer than rocking horse shit. 

[flapjackboy]

That was not a bad buy at all at $50. I can only find it for around $90 online now. At that price it is not as good a deal but still not a bad meter overall.

It appears to be available here for 56.70 Euros, which is about $62 (plus tax).

Yeah, tried to order one from there, but the minimum order from there is €150. Any site that tells me I have to spend a certain amount before they'll even take my order can go fuck themselves.

[rolycat]

That was not a bad buy at all at $50. I can only find it for around $90 online now. At that price it is not as good a deal but still not a bad meter overall.

It appears to be available here for 56.70 Euros, which is about $62 (plus tax).

Yeah, tried to order one from there, but the minimum order from there is €150. Any site that tells me I have to spend a certain amount before they'll even take my order can go fuck themselves.

The McCheck DM-303 branded version is available on eBay for around 60 Euros (£44) delivered. For example from Pinsonne or NG-Elektronik shops.

[retiredcaps]

Got this exact same meter about 10 years ago and it has served me really well until just the other day, when it died on me after it fell off the workbench. 

If you have a scope or another meter that measures HZ, do you see any sign of life on the oscillator?

There is a datasheet for the FS9922-DMM4, see if you are getting VDD on the IC.

[Monkeh]

I actually have three of these, two with failed ICs. They're pretty reasonable little meters. The jacks do indeed suck, I spent a while modifying mine with some of these: http://www.rapidonline.com/cables-connectors/4mm-pcb-socket-67718

At least I think it was those.. much better now. E: Nope, not those, something threaded. Probably salvaged.

A set of fuses and fuseholders from one of them went into my UT61E.

The burden voltage on the mA range is significantly better than my other meters. Quite useful for power measurements.

If you ever need any spares, rolycat, just shout.

[retiredcaps]

I actually have three of these, two with failed ICs.

How long did you have these until the ICs failed?  Did they fail on their own or due to some oops moment?

[Monkeh]

I actually have three of these, two with failed ICs.

How long did you have these until the ICs failed?  Did they fail on their own or due to some oops moment?

I bought them that way. I got all three for £30 or so on eBay, customer returns. No idea what happened to them, all I know is there are pins connected which really ought not to be. Probably some moron tried to measure an electric fence or something equally dumb.

I keep meaning to order some replacements off Aliexpress or the like, but I never really get around to it. I'd have to fix the input terminals and buy fuses, and new fuse clips for one of them..

[retiredcaps]

I bought them that way.

I also buy broken or parts meters, if they are cheap enough, in hopes of fixing them for learning purposes.  I have noticed that the meters, in my collection, with bad ICs are Fortune Semiconductors (3 for me so far).

In Martin's UT90C video, it was also an Fortune Semiconductor IC that died a sudden death.



It is possible that the designers aren't putting enough input protection to protect the IC or the IC itself can't withstand any "oops"?  Regardless, I now shy away from bidding on broken meters that use this brand IC.

[Monkeh]

I bought them that way.

I also buy broken or parts meters, if they are cheap enough, in hopes of fixing them for learning purposes.  I have noticed that the meters, in my collection, with bad ICs are Fortune Semiconductors (3 for me so far).

In Martin's UT90C video, it was also an Fortune Semiconductor IC that died a sudden death.



It is possible that the designers aren't putting enough input protection to protect the IC or the IC itself can't withstand any "oops"?  Regardless, I now shy away from bidding on broken meters that use this brand IC.

Well, none of these meters have any MOVs or anything in them, so I imagine the chips are just a bit fragile.

Seeing as I still have the image around, here's the insides of what I did to mine.



Little bit of epoxy to make things fit, don't mind the great piles of brass dust from cutting the jacks down to fit.

[flapjackboy]

The McCheck DM-303 branded version is available on eBay for around 60 Euros (£44) delivered. For example from Pinsonne or NG-Elektronik shops.

Thanks for that, just ordered one. You are a lifesaver.

Think I might send the busted one to Dave for a teardown.