Wierd looking Shunt....  - Page 1
Forum section: electronics / testgear

author: groovesonshunt
author_rank: Contributor
timestamp: December 20, 2022, 12:05:39 pm
content: Some time ago, I got myself a Monacor DMT-4010RMS Multimeter. (Danish Company)After some time, the display would flash at the Volt setting when I came close to touching it. I then opened it up, and found evidence that it had been tampered with. The Shunt had big balls of solder and deep grooves, solder splatter, fingerprint on the inside of the display.I have only taken apart the main cover into the fuses, so it would not warrent the guarantee.Have anyone seen grooves on a Shunt like this before?I got a new one sent back to me, but it started to make the same flashing display error as the first one. Opened it up and found the same grooves on the Shunt. Maybe there is some dirt on the traces, behind the selecter wheel, but I don't want to take it further apart due to the warranty.The COM test probe also had a smaller size plug, and had a hard time making contact. Worked fine with another set of probes.

author: srb1954
author_rank: Super Contributor
timestamp: December 20, 2022, 12:09:04 pm
content: Maybe the nicks in the wire and the solder blobs are a crude way of adjusting the shunt resistance to bring it into spec.

author: groovesonshunt
author_rank: Contributor
timestamp: December 20, 2022, 12:14:59 pm
content: These are the probes from the new meter.

author: Slh
author_rank: Regular Contributor
timestamp: December 20, 2022, 01:21:59 pm
content: The solder blobs are weird but the nicks are not.Current shunts are often adjusted by trimming them mechanically. You find it on all sizes. Smaller resistors might be be laser trimmed but it's the same thing really. Make all of them fractionally under spec and cut them to increase the resistance until it's within spec.

author: BillyO
author_rank: Super Contributor
timestamp: December 20, 2022, 02:20:38 pm
content: The solder blob is there to fix a nick that was cut to deep.I prefer filing the shunt. Much better for getting a precise adjustment but it does take a little longer.

author: groovesonshunt
author_rank: Contributor
timestamp: December 20, 2022, 02:48:36 pm
content: here is how the meter is acting and a few other observations....

author: BillyO
author_rank: Super Contributor
timestamp: December 20, 2022, 02:52:34 pm
content: Good lord! That's atrocious! They certainly have some serious production issues.Can you get your money back? Then get yourself a Brymen or even a UNI-T.Edit: It seems they are actually a German company out of Bremen. That looks suspiciously like a stenciledcheapChinese meter.If you don't mind y asking, how much was it?

author: Fungus
author_rank: Super Contributor
timestamp: December 20, 2022, 02:55:10 pm
content: Quote from: groovesonshunt on December 20, 2022, 12:05:39 pmYes. That's how they calibrate shunts.(you bite the shunt with a pair of cutters and it increases the resistance a bit)

author: BillyO
author_rank: Super Contributor
timestamp: December 20, 2022, 03:02:49 pm
content: It looks like it sells for about $150 Euro. That is way too much for a 3.5 digit meter, especially one with such terrible build.

author: coromonadalix
author_rank: Super Contributor
timestamp: December 20, 2022, 03:09:20 pm
content: one brand to avoid ? they look like the CEM brand

author: groovesonshunt
author_rank: Contributor
timestamp: December 20, 2022, 03:43:13 pm
content: Quote from: coromonadalix on December 20, 2022, 03:09:20 pmIt sure does!

author: AVGresponding
author_rank: Super Contributor
timestamp: December 20, 2022, 03:44:29 pm
content: Very much like a rebadged CEM DT9961

author: BillyO
author_rank: Super Contributor
timestamp: December 20, 2022, 03:51:57 pm
content: Quote from: AVGresponding on December 20, 2022, 03:44:29 pmYes. Which is a $40 meter.

author: Stray Electron
author_rank: Super Contributor
timestamp: December 20, 2022, 05:46:34 pm
content: Quote from: Slh on December 20, 2022, 01:21:59 pmExactly. It's not at all hard to find large external current shunts have been filed. In urgent situations I have filed resistors to raise their value. In one company that I used to work for, a production line shutdown costs the company $60,000 per hour so you didanythingthat you had to in order to get a machine up and running again A S A P. In that case I eventually got a complete replacement circuit board and I kept it on hand but the old board with the modded resister never failed so I never swapped it out.I think the poster that said that it had been filed too deeply and that they soldered up the notch and filed a new one is most likely correct.

author: Fungus
author_rank: Super Contributor
timestamp: December 20, 2022, 06:11:34 pm
content: Quote from: Stray Electron on December 20, 2022, 05:46:34 pmIf it has solderandbite marks then the calibrator was having a bad day.

author: Gyro
author_rank: Super Contributor
timestamp: December 21, 2022, 11:50:03 am
content: I wonder if the solder blob is where they squeezed the cutters a bit too hard and actually cut through!Yes, the better quality shunts are filed or ground over a long length for uniform dissipation and accuracy. They also have crimped areas near the ends to ensure that they sit at a predictable height (wire length) above the PCB. Fluke are probably best (in a handheld anyway), they weld a U shaped piece of wire across each end of the shunt so that they can do proper 4 wire Kelvin sensing.

author: groovesonshunt
author_rank: Contributor
timestamp: December 21, 2022, 12:40:25 pm
content: Quote from: BillyO on December 20, 2022, 02:52:34 pmYes, I will get my money back. I paid 120 US, and now its at 178 US.https://elektronik-lavpris.dk/p116583/dmt-4010rms-digital-multimeter-dmt-4010rms-professionel/

author: groovesonshunt
author_rank: Contributor
timestamp: December 21, 2022, 12:51:23 pm
content: https://www.monacor.de/They have the exact same meter on the front page, lower down.

author: RoGeorge
author_rank: Super Contributor
timestamp: December 21, 2022, 01:25:57 pm
content: Quote from: groovesonshunt on December 20, 2022, 12:05:39 pmThat's shunt tuning for calibration. Dents make the shunt resistance higher, blobs of solder make the resistance lower.

author: AVGresponding
author_rank: Super Contributor
timestamp: December 21, 2022, 03:00:36 pm
content: Quote from: groovesonshunt on December 21, 2022, 12:40:25 pmThat's a very disappointing pricing policy. Are they considered a reputable company, otherwise?

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: December 22, 2022, 02:05:27 am
content: Quote from: BillyO on December 20, 2022, 02:52:34 pmThat is exactly what 'Monacor' does. Since about 40years. Throwing the cheapest and crappiest electronics at customers mainly in the German speaking area. Although there are exceptions. Their dipmeter was not much worse than the other eastern makes and they sold a simple resistance decade with slide switches for 50.- when even the 'NBN' range of mini-decades did not exist for 10years. You have to look at least twice at everything bearing that name. The only multimeter that I've seen from them until now was such an Volts, Ohms, and DC250mA thing with jacks that were neither 2.3 nor 2mm. Yuck. But round here, known yuck.

author: groovesonshunt
author_rank: Contributor
timestamp: December 26, 2022, 08:51:18 pm
content: In one of Dave's videos 12 years ago, he showed a meter from Extech that looks very familiar to the Monacor...if not the same.He was also not very impressed with the board layout, or the meter in general. So many things wrong with it.

author: Wrenches of Death
author_rank: Regular Contributor
timestamp: December 27, 2022, 04:09:25 am
content: Quote from: Fungus on December 20, 2022, 06:11:34 pmI've seen the dyke bites in shunt wires for decades, but this is the first I've seen of the solder blobs. It doesn't take much imagination to visualize the value changing each time it got warm enough to soften or melt the solder.WoD

author: AVGresponding
author_rank: Super Contributor
timestamp: December 27, 2022, 10:27:32 am
content: Quote from: Wrenches of Death on December 27, 2022, 04:09:25 amIt's called "adaptive resistance"

author: Fungus
author_rank: Super Contributor
timestamp: December 27, 2022, 12:30:08 pm
content: Quote from: Wrenches of Death on December 27, 2022, 04:09:25 amIf you're getting your shunt over 250 degrees Celsius then maybe you're Doing It Wrong,

author: AVGresponding
author_rank: Super Contributor
timestamp: December 27, 2022, 10:11:51 pm
content: Quote from: Fungus on December 27, 2022, 12:30:08 pmOr you're testing the limits of the component...

author: iet
author_rank: Frequent Contributor
timestamp: December 27, 2022, 11:01:50 pm
content: Quote from: groovesonshunt on December 20, 2022, 12:05:39 pmI have seen such shunts in cheap Chinese multimeters.

author: Wrenches of Death
author_rank: Regular Contributor
timestamp: December 28, 2022, 12:18:35 am
content: That's a pretty high temperature. I use only REAL solder with a melting point of about 360 degrees fahrenheit. I think it's 180 degrees on the "C word" scale, which I don't use.If it doesn't have lead in it, then it's not REAL solder and it's not on my bench.LEAD FOREVER! Resist government tyranny!WoD

author: groovesonshunt
author_rank: Contributor
timestamp: January 05, 2023, 02:43:25 am
content: I got my eye on a Brymen BM789 instead...

author: BillyO
author_rank: Super Contributor
timestamp: January 05, 2023, 08:22:27 pm
content: Quote from: groovesonshunt on January 05, 2023, 02:43:25 am