eBay Gossen Metrahit 2+ neglected

[tocsa120ls]

Hi Everyone,

as my first post, let me tell you a short story about something which should be a no-brainer. So I bought this multimeter off eBay for a reasonable price. Brand new they go for ~€220, used around €150, I bought it for €90 http://goo.gl/zr5w7A - neat, huh?
The guy didn't specify anything, just 'good condition, see picture'. Now, having held this in my hand, you probably wouldn't see a ding if you ran it over with a car, but I didn't know that before.

One problem: it shuts itself off in about a minute after power-on. Batteries, right?



Uh-oh. Now, If you don't know why this is bad: first of all this means the owner didn't take care of it, so he might neglected it in other ways. Second, this not only means replacing a battery holder - leaked battery acid can travel over wires (capillary effect) and actually damage the PCB on the other end! As you can see on the picture, I cut the holder off, and stripped the negative wire, the copper strands are already discolored. Crap.

Now, this is a _really_ well built instrument. How far along do you have to strip it to get to the two solder joints on the board?



Just this far. That's the bare naked LCD sitting on top of its holder in the upper left. I marked the connector 'TOP' on the top side, for my peace of mind.



Sorry my phone froze on the picture in which the board still had the wires, but you could see a greenish crystally spot around the negative wire, about 3mm in diameter. I cleaned it up with alcohol. I'm not really a chemist, so I'm not sure if this is enough to deactivate the acid, I hope it is.



Back together. It seems it skirted the death-by-battery-acid and also the forgot-to-attach-esd-strap-at-first events. Btw, that battery should be over 4.5V 

[Robomeds]

Interesting.  Glad you got it fixed.  It's rather gratifying to fix something like that so readily.  Kind of reminds me of how cheap the fix was for the Ideal meter I tore down a few months back... too bad it too someone with more knowledge than me to realize the problem 

Anyway, if you have more interior shots of the meter I would be interested in seeing them.  The Gossen meters have virtually no presences in the US market.  I don't know if that's because Fluke is so good that no one else bother's in their home country (new Agilents aside) or if that's because Gossen just doesn't have a good sales base here.  Either way, I think it's interesting to see designs that clearly aren't low cost yet also aren't "Fluke 87 copies". 

[Orange]

Nice to see that you got it working.

My experience is not that good with Gossen Metrawatt Metrahit 1 and 2 meters. I have seen to many that cannot be repaired anymore. No diagrams either.
Personally I would stay away from them, even if you could have them for a song..... Better get a Fluke.

[retiredcaps]

My experience is not that good with Gossen Metrawatt Metrahit 1 and 2 meters. I have seen to many that cannot be repaired anymore.

Would you care to elaborate on their problems? 

If shipping to the USA and/or Canada is not too much $$$ and you are going to throw away those Gossen's in the trash/recycle bin, I will pay the shipping coststo USA/Canada to get them.

[nanofrog]

The Gossen meters have virtually no presences in the US market.  I don't know if that's because Fluke is so good that no one else bother's in their home country (new Agilents aside) or if that's because Gossen just doesn't have a good sales base here.  Either way, I think it's interesting to see designs that clearly aren't low cost yet also aren't "Fluke 87 copies".

Don't think they've been imported that long, and were imported under the brand of Dranetz. Now seem to be in the process with replacing them with Gossen branded units, with at least some of the P/N's changing (i.e. Dranetz Drantech Ultra is replaced with the Gossen MetraHIT 230B, <aka MetraHIT 30M model in Germany?>). BTW, this is a 6.5 digit, 1.2M counts handheld.

They're also rather expensive, even compared to Fluke for similar specs & features, so that has something to do with it as well IMHO (i.e. cheapest meter is $450, and the PC cable & software costs the same; meters go up from there, with the 230B going for ~$1218 @ tequipment.net).

[tocsa120ls]

Anyway, if you have more interior shots of the meter I would be interested in seeing them. 

Pleased to give you a few more pictures. When I fixed it 2wks ago, I put in batteries that I wasn't sure about. Now replaced them, and got a few a$$ shots - sorry, if I don't have to, I will not pull the PCB out, the other side with the LCD installed is just a black plastic plate. You have to unscrew the LCD and unsolder the LCD backlighting to get to the PCB. Sorry mate, hope the pics do the meter justice.

CPU Datasheet: http://www.ic-fortune.com/upload/Download/FS9922-DMM4-DS-11_EN.pdf

New batteries:


The screws have metal inserts in the the housing, but I was a little surprised to find single slot screws, not the usual crosshead ones:


Blast shields around the HRC fuses cast into the back:


Compared to other meters I have, the rotary switch has few contacts (gold coated) - a good thing in my mind


Main CPU (I think) with the 4MHz crystal, I just noted the IR diode and receiver combo I guess this way it's cheaper than using the obligatory Toshiba 2-in-1 transceiver.


Held the casing up to light, it is thinner in the region the IR stuff faces (but the big green rubber bumper has no cutouts, so presumably it is to be removed when using the IR communication)


Really can't comment on the input stage, I'm not nearly as experienced in equipment design as some folks around here.

[saturation]

It looks very well made.  I would suspect its higher price is that its really made in Germany, the volume of sales isn't as large as Fluke so profits are lower,  and EU has more regulation for electronics manufacturing than the US.

Had it been available in the USA for that price I would have gotten one, easily.

[Napalm2002]

I had bought a Drantech outdoor from grainger and it was super cheap bec they were dumping them. Gossen is coming to the USA and I hear they will be expensive. They have a few cool features but all in all if buy fluke, unless they price was comparable

[nanofrog]

I had bought a Drantech outdoor from grainger and it was super cheap bec they were dumping them. Gossen is coming to the USA and I hear they will be expensive.

Not like the regular pricing when they were sold under Dranetz was cheap... 

[retiredcaps]

CPU Datasheet: http://www.ic-fortune.com/upload/Download/FS9922-DMM4-DS-11_EN.pdf

Thanks for the teardown pics.

Does the Gossen overshoot when taking DCV readings?  For example, if you measure a simple 9V battery, does the lcd display initially 12.12V, then 9.00V DC?   I find a lot of these Fortune Semiconductors ICs overshoot.

[tocsa120ls]

Does the Gossen overshoot when taking DCV readings?  For example, if you measure a simple 9V battery, does the lcd display initially 12.12V, then 9.00V DC?

No, it does not. If you connect/disconnect the test leads to the battery quickly in DCV auto-ranging mode, sometimes you get an intermittent value like 568.11mV, but then it always stabilizes at 9.18V.
Beeper is latched, clear sounding, but because of the latch, you can sense a few ms delay in the sound.
Frequency measurement is good up to 20kHz (datasheet shows max 1kHz so not sure what goes on there)
Diode measurement OK, it lights up the Cree XR-E 7090 LEDs but does not measure voltage drop (the forward voltage on those is ~3.3V) - I have some funky hi-output IR 'star' LEDs, those it measures correctly at 1.1V. 1N4148 measures at 0.685V.
The tilting bail is phenomenal, rubberized wide feet, easy to clip in/out, holds the device really stable.

My only 'pain point': the resistance auto-ranging is slow, you're not going to use this DMM to sort out your resistors after you've dropped them on the floor.

[retiredcaps]

Does the Gossen overshoot when taking DCV readings?  For example, if you measure a simple 9V battery, does the lcd display initially 12.12V, then 9.00V DC?

No, it does not.

Thanks for doing that test.  I wonder the following observation has anything to do with the non-overshoot?

I noticed the manual for the 2+ says 2 measurements/sec while the FS9922 datasheet says 3/secs.  The manual also says 20 mesurements/sec for the bargraph while the FS9922 datasheet says 30/sec.