EEVblog #173 - Gossen Metrahit Energy Multimeter Teardown

[SnakeBite]

nice review dave! i really like this meter but you didn't mention where we can buy this meter from?

dave , i found the green smd resistor here - it's high voltage precise resistor.

http://www.ohmcraft.com/marketinfo/powersupply/

Ido

[mikeselectricstuff]

Re. that mosfet pair in series with the fuse - I was curious about what that was about, but then realised  there's probably a lower range current shunt across them for lower current ranges - maybe that one you identified on the rear?
Those wiggly resistors may be designed for on-board laser trimming of the thick section in the middle.
Looks like those relays are latching ones, so not a big deal for battery life.

[insurgent]

I almost clicked "dislike" on this video. Showing off that meter made me jealous! That's an excellent piece of craftsmanship!

About those "curious" parts: searching the web, they look like a "serpentine cut" laser trimmed resistor. And the lack of the usual thick film resistor network indicates that Dave is spot on with his determination of that the part is. Cool looking devices!

Thanks for another cool teardown video!

[saturation]

Great review, I hope to acquire one of these in the future.

On the side, has anyone seen the thread on older Gossen models since discontinued but still made in India under a different brand name? 

https://www.eevblog.com/forum/index.php?topic=3527.msg47152#msg47152

They are more affordable for one who wants Gossen technology.

[Kiriakos-GR]

I would feel much better if some one can specify or describe,
the target group of technicians or scientists who will find useful the specific tool.

Every girl wants to have a shiny ring on her finger, but mostly because some one else will pay for it.   

[EEVblog]

Re. that mosfet pair in series with the fuse - I was curious about what that was about, but then realised  there's probably a lower range current shunt across them for lower current ranges - maybe that one you identified on the rear?

Yes, that was my thought too. I didn't bother to trace it out to what resistor(s) it was though.

Those wiggly resistors may be designed for on-board laser trimming of the thick section in the middle.

That would be very interesting if they actually did laser trimming on the final assembled board.

Dave.

[NiHaoMike]

The Agilent meters I use at work have internal relays as well. They make a very distinctive sound when there are 3 or 4 meters connected to a PC and they all switch at almost the same time.

Does the Gossen recharge the batteries when plugged in? That would be very useful if the meter is regularly used for data logging where mains power is not available or where the power adapter would couple too much noise into the circuit under test.

[Kiriakos-GR]

Nop , no recharge for the batteries ..

But hey do not keep it as secret, what model of Agilent meter uses relays ?

So far I was aware for my oldie analog Metrawatt,
now I have see those again on Dave's meter ... I am dying to find out who is third device that uses those too.  

[alm]

Almost all bench/system DMMs use relays. They have better isolation than MOSFETs, and rotary switches don't work well with remote control.

[EEVblog]

The gossen can actually switch into any mode via the PC control software regardless of the rotary switch position.
It's rather odd to see it switch into current mode with the range switch on ohms!

Dave.

[Ed.Kloonk]

The gossen can actually switch into any mode via the PC control software regardless of the rotary switch position.
It's rather odd to see it switch into current mode with the range switch on ohms!

Dave.

That's a fire waiting to happen, isn't it? 

[PelzigesOhr]

Did you check out the English Gossen website? I just went there out of curiosity. They put up a link to the teardown video on the right hand "showcase" box which apparently displays on every single subpage. Propably just to show off their mod resistor  If you check out their "videos" section you can see that they even put links to generic videos like accumulator measurement, just because a Gossen meter was used. Seeing how much influence one blogger can have amazes me every time.

[EEVblog]

Did you check out the English Gossen website? I just went there out of curiosity. They put up a link to the teardown video on the right hand "showcase" box which apparently displays on every single subpage. Propably just to show off their mod resistor  If you check out their "videos" section you can see that they even put links to generic videos like accumulator measurement, just because a Gossen meter was used. Seeing how much influence one blogger can have amazes me every time.

Yeah, they feature my videos on almost every page including the home page!
Guess they like them.
Incidentally, Gossen were the first manufacturer to ever acknowledge my blog and send me stuff, back at episode 40 or something.

Dave.

[joeqsmith]

During the video you fast forward as you take the meter apart.  You remove the covers and 4 screws. Then as you try to remove the cover, it hangs.  You struggle and are saying something.  Another screwdriver comes out and you appear to pry the meter apart.  You never then show this side of the meter in detail.

I suspect I will be pulling one of these apart in the next week or so. Are there latches the need to be released to remove the cover without damaging the plastic covers?  If so could you detail this area for me. 

Thanks.

[joeqsmith]

Howardlong helped me out with this one.  It does appear there are a couple of internal latches.  A T10 and good to go.