Gossen Metrahit 27i calibration - Page 1
Forum section: electronics / testgear

author: Taimer81
author_rank: Regular Contributor
timestamp: March 26, 2025, 08:20:45 pm
content: Hello!Acquired Gossen Metrahit 27i.There is an error of 0.5% when measuring VDC. Please tell me how this multimeter is calibrated.Foto -https://photos.app.goo.gl/V71fAc4RzCqzo9d46Thank you.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 26, 2025, 08:47:58 pm
content: They are software calibrated, you can't do nothing manually, no manual commands if there is, was ever leakedThe software is sold separately (priceyyyy) but must be connected to fluke calibrators, witch no one can afford ... and you need the infrared usb-hit or serial Si232 interfaces tooAlas send it to cal facilitiesSame goes for the old Metrahit models (i have the 16 27i 28s 29s 30m) and the Metraline models ...

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 07:48:24 am
content: Thank you for your reply.I'm upset. I think the verification (including delivery) will come out as the cost of a used device. I bought it with my hands in good condition for $ 500. There was no way to check before the purchase. I was sure that it would measure accurately, I have old multimeters, including the Fluke 87v and Escort 2030, which show very high accuracy in measurement, although many years have passed since their release. Milliohmmeters and microohmmeters shows very accurately. With an increase in resistance to kOhm, the error increases, but within acceptable limits, it is still inferior in accuracy to the Fluke 87v and Escort 2030.

author: J-R
author_rank: Super Contributor
timestamp: March 27, 2025, 08:29:25 am
content: I'm doubtful that this is a calibration issue. Either your reference is incorrect or the multimeter is damaged. Do you have proof that the reference is correct? Test it with multiple meters connected at the same time since regulation may be poor.I see some evidence of battery leakage. Have you thoroughly cleaned the PCB?

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 08:44:41 am
content: Thank you for your response.I have several multimeters, in fact I have a lot of them, I have a hobby \ - multimeters. There are two calibrators. I checked the voltage source with other multimeters, the error is only in metrahit . I assume that the problem may be in some \ component (capacitance, resistor ) or contamination/oxides inside the board .

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 08:54:15 am
content: In YouTube I saw a video, a person when reviewing Agilent (Keysight) U1273A had a problem with the accuracy of voltage measurement. Disassembled and performed, as I recall, cleaning of some component. I don't remember exactly and I can't find the video. What you can clear.

author: J-R
author_rank: Super Contributor
timestamp: March 27, 2025, 09:38:14 am
content: According to the METRA HIT 27 manual, the input impedance is only 2.1M Ohms, which is a bit lower a typical 10M Ohm DMM. So it's possible the reference isn't handling that correctly. It's worth a double-check by having multiple trusted DMMs connected to the reference at the same time just to be sure. It may not be the case, but this is something that could be a factor. The 2.5V reading is actually pretty close, which might make sense if the DMM is dragging the reference down but only on the higher voltages. Also, this is a 30,000 count DMM, and in my experience if the calibration is off it will be very bad at either the middle or upper end of the range but quite good at the lower end. So I would have expected the 5V reading via the 30V range to be quite good even if the calibration was off.IPA is the go-to cleaning agent according to the forums, but still use some care with certain components. I'd focus on exposed traces/contacts that could have small amounts of leakage due to contamination, especially the input jacks.Of course the battery contact mess probably use vinegar to neutralize and mechanically break off any corrosion, then clean as best you can. Sometimes you may have to replace metal contacts if they've been eaten away.

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 10:05:50 am
content: Thank you for your response .There are traces of a battery leak . This can be found on the back of . To remove it, I need to unsolder the wires . I'll get to that . When measuring small resistances, the readings are accurate . The error occurs when zooming in . I think it has something to do with each other. When measuring the voltage, this is also observed.

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 10:37:01 am
content: Quote from: J-R on March 27, 2025, 09:38:14 amTell me, please, maybe this is a defect in production? As I understand it, this is a voltage divider. Could it have been accidentally soldered?

author: coromonadalix
author_rank: Super Contributor
timestamp: March 27, 2025, 10:42:10 am
content: yess for the corroded cell clip, the one on the pcb is harder to get, for the 2x cell i changed the battery clip, lucky for me, the one on the pcb is perfectyes buying used Gossen can be problematic, i paid 855 euros for the 30m in a bid war, (add transport and customs over that) and it costed 160 $Cad to get it calibrated (internals where perfect) , same price for an 28spaid 500 usd for the 27i and needed to buy the kelvin clips, they where not there, was lucky to get the case and everything else, usb-hit too, even the originals fuses sell for a lot ..i already knew how much the calibration costed for theses, since they are not my 1st purchasessome lower models have maxim dmm chip in them, not full Gossen technology / asic found on the 28 29 30for the input jacks as you see they are isolated and press fitted or molded in place, if are not fast while un-soldering the wires, you may deform the casing holding themand be careful working on theses pcb, it is not easy to remove the clip wiresmy day to day meter is the Siemens B1105 (28s)still someone sells them on ebay.de once in a while around 270 euro, from a closed company (they had many) no affiliation, i bough it from that guy@Taimer i dont know how you paid for your 27i, and what came with it, was it on ebay.de ... ? there was some pricey one there ...

author: coromonadalix
author_rank: Super Contributor
timestamp: March 27, 2025, 10:43:50 am
content: for the short, remove it and check if you have a continuity under them / pcb trace, or it is really a bad solder job and could affect the reading(s)bad quality check for that ?? or some rework parts change ? you see others with almost the same blob effect ?? or wave solder quality ...good eyes

author: J-R
author_rank: Super Contributor
timestamp: March 27, 2025, 10:49:36 am
content: I don't think that solder bridge is an issue. It looks like it is just a via going through the board. Shine a bright light through the PCB to see better.

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 02:57:17 pm
content: There was a crib for the battery in the back. Unsoldered it to take a picture of.

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 03:07:32 pm
content: Comparison with another multimeter

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 03:08:59 pm
content: Comparison with another multimeter.

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 03:09:42 pm
content: Power supply voltage. I opened it and cleaned it. I examined. It looks like the whole. I do not know where to look for. I think that the capacitances of capacitors do not affect the correctness of the voltage measurement readings.

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 04:10:31 pm
content: There is an error in measuring the resistance in different operating modes. When measured with a pulse current of 1A, it underestimates the resistance.

author: coromonadalix
author_rank: Super Contributor
timestamp: March 27, 2025, 04:52:25 pm
content: youre not gonna love me but your non kelvin probes ... trash this setup and use proper kelvin probes not theses cablesyour tagrea thing does gives 6.04 milli ohms, but in the longest display form 0,00604 and the 27i does report it in a direct milli ohms display 6.04m ohms ??it is a very sensitive range any movement does changes things etc ... for the voltage i may understandbut where im not getting you is, i would not judge by this reference board, unless you have more, and do multiples compares ... your appa 505 is a real 10k counts, not a 100k, same with other gimmicks with other brands like 50k counts with an 500k counts mode like i have.the Gossen 27i is a 31k counts ... those references are normally done with an 6.5 digit meter aka 1,200,000 counts dmm or elseis the appa calibrated, before doing any comparei tried my 27i with 0.0035% fluke precision resistors with real kelvin probes and it does fit the numbers

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 05:32:31 pm
content: I contacted the seller and explained everything. He agreed to return the money. 500$, I think this is a lot for a device with a DC voltage measurement error of 0.4%?

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 05:44:17 pm
content: Quote from: coromonadalix on March 27, 2025, 04:52:25 pmI have precision resistors and 0.02% \ resistance stores. At low resistances, 27i is a very accurate sensor. But when measuring 4000 ohms-1000 kOhms, it has an increasing error of up to 0.6%, both when measuring resistances and DCV.

author: Taimer81
author_rank: Regular Contributor
timestamp: March 27, 2025, 06:37:46 pm
content: Thermovoltage Compensationhttps://photos.app.goo.gl/35nMxWf4h956jJVA6

author: daisizhou
author_rank: Super Contributor
timestamp: March 28, 2025, 01:17:28 am
content: You need to thoroughly clean the bottom, details

author: Taimer81
author_rank: Regular Contributor
timestamp: March 29, 2025, 08:32:10 am
content: Quote from: daisizhou on March 28, 2025, 01:17:28 amThank you for your reply.Please tell me, this should be done under the resistors of the voltage divider?Red elements under the divider resistors what is it?

author: daisizhou
author_rank: Super Contributor
timestamp: March 29, 2025, 08:50:35 am
content: The red part is the fixing glue.You need to clean the electrolyte leak carefully,Especially the electrolyte soaked area, it is best to disassemble the components for cleaning

author: coromonadalix
author_rank: Super Contributor
timestamp: March 29, 2025, 12:03:03 pm
content: @op did you return the meter ? as you said, asked for a refund ?

author: Taimer81
author_rank: Regular Contributor
timestamp: March 29, 2025, 03:37:30 pm
content: Quote from: coromonadalix on March 29, 2025, 12:03:03 pmThe seller partially refunded the money. As a result, the multimeter costs me 300 $Not sure if this is a good deal. But now there is no way out, you need to put it in order )

author: Taimer81
author_rank: Regular Contributor
timestamp: April 02, 2025, 05:34:32 pm
content: I cleaned everything I could reach. Unfortunately, it did not give any results. I don't know what to do. I think the only thing left is to calibrate.

author: J-R
author_rank: Super Contributor
timestamp: April 03, 2025, 03:01:37 am
content: Since it's so far off, I would still suspect there is something wrong. Calibrating it might not be possible until it's repaired. Check all the components you can. Capacitors, resistors, diodes, transistors... You could trace the input paths to see what components might be more likely than others to be faulty.

author: Taimer81
author_rank: Regular Contributor
timestamp: April 03, 2025, 05:42:27 am
content: I assume that most multimeters use a similar voltage measuring scheme. Protection and input resistors are also used. Please provide an electrical diagram of a multimeter as a basis for checking circuits and understanding them. Thank you.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 03, 2025, 09:48:57 am
content: google is your friend as for searching items videos how to .... you need to do your own searchyou may have similarities and not, extra security parts, mov's gaz tube etc ... there are many schematics floating on the web, you have a Maxim ic if i recall for the dmm part, search it's application notes, design notesGossen is Gossen, Fluke or others ... other parts are not, and we never found any leaked Gossen schematics, they functions switching is way different,because of the very low pcb traces counts for the diali think with that meter, you bought something who may go beyond your knowledge, you need to understand a few things about it,it's a peculiar one, i had to understand how it work because of the kelvin inputsand i may wrongly assume you don't want to send it to cal labs or try to find any route avoiding thatyou did not answer if you remove the short blob between the resistors if it change measurements, and if once removed still the pcb traces under are still the same blob or not,seeing the Daks cal sticker, it was calibrated many many years ago, and sadly it may have drifted, thats a possibility

author: timeandfrequency
author_rank: Frequent Contributor
timestamp: April 03, 2025, 10:40:24 am
content: Schematics have never been published.Might be a high voltage divider that has been dodged and lost some precision.But replacing it would probably not solve the issue.These meters are probably digitally compensated : so it needs to poke the calibration values to set it back to specs.Chances to succeed with a DIY repair are rather low.Unfortunately.

author: Taimer81
author_rank: Regular Contributor
timestamp: April 03, 2025, 03:41:37 pm
content: Quote from: coromonadalix on April 03, 2025, 09:48:57 amI would love to send it, but they refused me.Quote

author: Taimer81
author_rank: Regular Contributor
timestamp: May 17, 2025, 10:57:56 am
content: Quote from: coromonadalix on March 26, 2025, 08:47:58 pmIn the list of calibration programs, none support calibrating the 27i model. This is very strange.

author: coromonadalix
author_rank: Super Contributor
timestamp: May 17, 2025, 01:51:33 pm
content: do your home work properlythe 27I is not a full Gossen unit, it supposed to have a maxim 31k count dmm icthat's why it is not listed in the Gossen calibration software

author: Taimer81
author_rank: Regular Contributor
timestamp: May 17, 2025, 03:55:27 pm
content: Quote from: coromonadalix on May 17, 2025, 01:51:33 pmYou are a good specialist. I appreciate it. Thank you. Do they perform calibration using software that is not commercially available?

author: coromonadalix
author_rank: Super Contributor
timestamp: May 18, 2025, 12:58:47 pm
content: i do have many gossens, had some Metrix too, but im no specialistit is just a matter of searching informations like teardowns and other things, i did search before buying theses meters of calibration possibilities in North America, costs and where i can send them if neededlike any other instruments or brands ...you ask tons of questions, you can or could have been answered them by yourself, but asking here is okay tooGossens x or x modelChauvin Arnoux aka Metrix ...from the start they are very expensive models and special in a sense, they are a niche productChauvin was able to provide at some point the ASYC software for many models, i havent tried to request for the latest version for the biggest/highest modelsmany other brands are now software calibrated, luckily some can be still be done manually, that's great if you have stable references like resistors and or voltages, but you may mess the precision of such instrumentsif you do a calibration, sadly it is costly, but do it properly, if not your instrument to me become worthlessi'm not a voltnut, but had some 34401a 34410a calibrated, some Gossens too, and for the others i have, i did compare them to the calibrated ones ...you need reference material ... meter or else ...i have some National Instruments 6.5 digit pxi and pci multimeter cards, the calibration prices for theses are absurdly high, way over the cards values, i'm in Canada and they request to be shipped in the USA for that ?and i admit : before getting theses i did not do enough researchs, they are okay, but if i need to cal them .... nay nayyou posted the Metrawin 10 software and the 90 series calibration sw, you can buy it, but pricey as hell over 1000 euro and more $, but you still need Fluke Calibrators who go with the 90 softwareand if you have one or many gossens, i think you already know the answers to your questions, no procedures, no serial commands have been leaked, no 90 software or even demos have been leaked ...nothing too, on the Metraline models, and nothing on their latest models versions, who are ultra expensivesadly if you can not get them out of your country for calibration, and be able to pay the high prices to calibrate them, sadly you may need to sold them, and try to buy things you can work withmaybe bench versions are better in some cases ...for a gossen collector, side notesi never calculated (i better not) all the $ i've put to buy them : Metratop 51, Metrahit 2+, 27i, 28s, 29s, 30m, B1105, Avometer m3045, Dranetz or Siemens clones or some Rishabh too, all their accesssories, infrared interfaces, transformers, sure i paid tons of cash, in the thousands for sure, alas some are sitting on a shelveand some may or will be resold, my fun has ended, i was about to shell lots of $ just to grab an 27 H+E car, just to get the missing orange holster, yep i almost have all the possible holster colors Gossen made / clones made ... minus the orange loll

author: Taimer81
author_rank: Regular Contributor
timestamp: May 20, 2025, 03:13:45 pm
content: Thank you for your reply!I appreciate and respect your experience.If you have the time and desire, please have a quick review on Metrahit 30М on YouTube.This is a very rare and unique multimeter.

author: daisizhou
author_rank: Super Contributor
timestamp: May 20, 2025, 10:08:47 pm
content: Quote from: coromonadalix on May 18, 2025, 12:58:47 pmHi I saw that you mentioned "ASYC software", I would like to ask whether it can be used on other analyzers besides digital multimeters?I mean calibration.I have come across a FLUKE VT650/VT700 gas flow analyzer,It seems that it also needs to be calibrated by software

author: coromonadalix
author_rank: Super Contributor
timestamp: May 21, 2025, 12:17:47 am
content: as far as i know, its only for their DMM calibration(s)

author: Taimer81
author_rank: Regular Contributor
timestamp: May 21, 2025, 06:17:06 am
content: Quote from: coromonadalix on May 21, 2025, 12:17:47 amPerhaps it is partially compatible with the ASIC IV ?ModBus registers are identical.