Author Topic: fluke dmm, really need help (Read 6739 times)

Cody Turner OKC · « **on:** July 12, 2018, 11:53:29 pm »

Hello everybody, I am more of a reader and watcher, than a poster, I have posted a few times in the last few years, mainly just browse all the posts.

So.. I have a few cheap multimeters, and I have been wanting a good quality, Fluke, or something along those lines, for who knows how long, I have been saving up for probably a year, no joke. So about 6 months ago my neighbor from a few houses down was selling a fluke 87 III, and I was very intrested, the payment that he wanted was to Mow, edge, weed-eat his front and back yard one a week, for 4 months, a total of like 16 some crazy times! AND I could not have the meter until i was finished, which was very sad, but even so i worked my butt off for the last 4 months doing my best, and on Monday I Finally finished, and got the meter,

I rushed home to start playing with it of course, and a few things seemed off-

Screen randomly restarting when i go into the 4 1/2 digit mode, beeper not always working, very dim backlight, etc-

but the main problem and question i have is about the fuses, so both of the fuses were shorted, I took them out went to every store that my older sister would take me to looking for matching fuses, After failing at every store I ended up buying a 20A fast blow ceramic fuse, and a 5 Amp equivalent, which were the closest two i could find to fit, now i know that they are way wrong for saftey etc, I just wanted to try and make a measurment,

so upon testing with them, WOW, the current readings were way, like 60mA off the pretty close matched value from all my other DMMs which all measured around the same, on all different values,

So, my first question is, would the maybe resistance of these very wrong fuses be the possible cause? Now i am to young to have a debit card, and ive begged everyone I know to let me order the fuses from the internet but everyone says no unfortunatly, so Ive come to accept the fact that it will be years before i get proper fuses, so i am guessing im just out of luck with using the meter for current readings on my new Fluke meter

could anyone tell me the resistance readings of the proper fuses so i can compare?

if i got a close enough match do you think i might be able to use it?

sorry for this long post, but ive been looking for hours now today for solutions and i am getting a headache, I am pretty torn up inside about it so I wanted to tell someone and maybe get a little help, it might seem like a small deal being just a few fuses but it was a lot of hard work and years of only dreaming to come to this, thank you very much to anyone who can assist, and have a great day!

ataradov · « **Reply #1 on:** July 13, 2018, 12:07:18 am »

Also, even regular household fuses should read 0 Ohm on that same Fluke. If you get something else it is either Fluke completely out of cal, or you've got some really bad fuses.

sleemanj · « **Reply #2 on:** July 13, 2018, 12:11:33 am »

You say fuses were "shorted". That is the correct state for fuses to be in, a direct connection from one end to the other. Either you mean "open" (no connection, blown), or your original fuses were ok.

NexusKoolaid · « **Reply #3 on:** July 13, 2018, 12:12:26 am »

You may be too young to get a debit card but being in the US you should be able to get an Amazon gift card, and there appear to be proper fuses available there.

Cody Turner OKC · « **Reply #4 on:** July 13, 2018, 12:15:44 am »

I reformatted it, sorry i didnt realise I was doing that while typing, so you dont think the fuses are causing the very wrong current readings, darn

Cody Turner OKC · « **Reply #5 on:** July 13, 2018, 12:17:00 am »

OOPS! I didnt realise I said that lol, They were open, no continuity- Thanks!

Cody Turner OKC · « **Reply #6 on:** July 13, 2018, 12:17:49 am »

hmm, I will put a picture, or the Specs that I can find for them soon

james_s · « **Reply #7 on:** July 13, 2018, 01:20:50 am »

The very first thing I would check is the battery since you mention the backlight is dim. If the battery is low it can cause strange behavior.

The Fluke fuses are special and they're not particularly cheap, but having the correct fuses is important for safety. It shouldn't affect the accuracy of the meter though.

Mr. Scram · « **Reply #8 on:** July 13, 2018, 02:32:21 am »

Quote from: james_s on July 13, 2018, 01:20:50 am

The very first thing I would check is the battery since you mention the backlight is dim. If the battery is low it can cause strange behavior.

The Fluke fuses are special and they're not particularly cheap, but having the correct fuses is important for safety. It shouldn't affect the accuracy of the meter though.

Yes, get the correct fuses. Getting a multimeter of this quality and reputation is no use if you mess that all up with the wrong fuses. Use the correct fuses and it should properly protect you from harm.

alsetalokin4017 · « **Reply #9 on:** July 13, 2018, 03:05:51 am »

OMG, Cody.... you worked really hard for that meter. Let's see... I suppose it must have taken you 2 hours to mow, edge and weedeat both yards. Times sixteen, that's 32 hours of hard labor. Figure 10 bucks an hour (a miserable rate for hard lawnwork) that's 320 dollars in sweat that you paid for that meter. That puts you very close to the cost of a brand-new, fully warranteed Fluke 87-V.

https://www.ebay.com/itm/FLUKE-87V-INDUSTRIAL-MULTIMETER/273312388438?hash=item3fa2b01556%3Ag%3Agr8AAOSwAC1Z673M&_nkw=fluke+87+-111&rt=nc

I think this neighbor screwed you.

That being said... let's see if we can confirm that the meter is fully functional at least. First you really do need to get the actual correct fuses, and the guy who enslaved you should really pay for them (they aren't exactly cheap). Once you have the right fuses and a new battery in the thing, we can guide you through some performance tests.

Shock · « **Reply #10 on:** July 13, 2018, 03:34:04 am »

Put a brand new battery in it first!

Second remove the fuses if they are open, it's only for current measurements and that can wait until you have tested the meter properly. So start by closing/shorting the leads on AC, DC, DCmV and seeing what reading you get and if the meter is malfunctioning. Then check the lead resistance and do a diode test by shorting the leads.

If the multimeter has dirty probes or contacts in either the leads or the sockets it's going to throw all your measurements out so it's essential to do this. Next you can read a battery and see if you can get a stable DC measurement or a set resistance on ohms etc and get an idea that the meter is behaving.

Then blow some money on the proper fuses. Let us know how you get on.

Shock · « **Reply #11 on:** July 13, 2018, 03:43:22 am »

The neighbor actually did you a favor even though it was a bit of labor on your end. You saved the money on buying the meter. So now you have done all the work you can forget about it.

Here is a video on testing the proper Fluke fuses, you should follow my earlier advice though and see if you have other problems first.

IanB · « **Reply #12 on:** July 13, 2018, 04:09:16 am »

Quote from: Cody Turner OKC on July 12, 2018, 11:53:29 pm

both of the fuses were shorted

Fuses are supposed to be shorted, that is to say a short circuit, which is to say they should have very little resistance and should beep on a continuity test.

Are your fuses shorted (as they should be), or open circuit (as they should not be)?

Cody Turner OKC · « **Reply #13 on:** July 13, 2018, 04:22:13 am »

Quote from: james_s on July 13, 2018, 01:20:50 am

The very first thing I would check is the battery since you mention the backlight is dim. If the battery is low it can cause strange behavior.

The Fluke fuses are special and they're not particularly cheap, but having the correct fuses is important for safety. It shouldn't affect the accuracy of the meter though.

I put a brand new 9V battery in it and it helped a few things like the light, I am only wanting to measure small currents DC and I Will get the correct fuses as soon as i have a chance trust me!

Cody Turner OKC · « **Reply #14 on:** July 13, 2018, 04:26:14 am »

Quote from: alsetalokin4017 on July 13, 2018, 03:05:51 am

OMG, Cody.... you worked really hard for that meter. Let's see... I suppose it must have taken you 2 hours to mow, edge and weedeat both yards. Times sixteen, that's 32 hours of hard labor. Figure 10 bucks an hour (a miserable rate for hard lawnwork) that's 320 dollars in sweat that you paid for that meter. That puts you very close to the cost of a brand-new, fully warranteed Fluke 87-V.

https://www.ebay.com/itm/FLUKE-87V-INDUSTRIAL-MULTIMETER/273312388438?hash=item3fa2b01556%3Ag%3Agr8AAOSwAC1Z673M&_nkw=fluke+87+-111&rt=nc

I think this neighbor screwed you.

That being said... let's see if we can confirm that the meter is fully functional at least. First you really do need to get the actual correct fuses, and the guy who enslaved you should really pay for them (they aren't exactly cheap). Once you have the right fuses and a new battery in the thing, we can guide you through some performance tests.

I know, a lot of work, but it was well worth it for how desperatly ive been wanting to get a better meter! I put a new battery and cleaned it up as good as i could, I did a bunch of checks on everything, except current without the proper fuses, I have tried knocking on his door like 5 times since! And my parents could care less to help, I cant really order the right fuses,I have no way to pay or anything, or enough money really!! but trust me I want fuses for it as bad as I wanted the meter!

I will post a picture of the fuses i got for a few dollars from home depot, that i thought maybe effect the current accuracy

Cody Turner OKC · « **Reply #15 on:** July 13, 2018, 04:28:13 am »

Quote from: Shock on July 13, 2018, 03:43:22 am

The neighbor actually did you a favor even though it was a bit of labor on your end. You saved the money on buying the meter. So now you have done all the work you can forget about it.

Here is a video on testing the proper Fluke fuses, you should follow my earlier advice though and see if you have other problems first.

I put a new battery and cleaned it up as good as i could, I did a bunch of checks on everything, except current without the proper fuses, I will post a picture of the fuses i got at store for a few dollars that i thought was messing up the current readings,

Cody Turner OKC · « **Reply #16 on:** July 13, 2018, 04:30:20 am »

Quote from: IanB on July 13, 2018, 04:09:16 am

Quote from: Cody Turner OKC on July 12, 2018, 11:53:29 pm
both of the fuses were shorted

Fuses are supposed to be shorted, that is to say a short circuit, which is to say they should have very little resistance and should beep on a continuity test.

Are your fuses shorted (as they should be), or open circuit (as they should not be)?

Yes I made a mistake! I meant that they were both Open not shorted!! Thanks!
I am trying to figure out how to post a image to show you guys the current cheap fuses I got

Cody Turner OKC · « **Reply #17 on:** July 13, 2018, 04:39:04 am »

Got it! Here are the attached images of the cheap fuses I got at the hardware store for a few dollars, unfortunatly there all I am going to have for quite some time, I am not planning to measure any AC current, only small DC currents in my little breaadboard things never over a hundred mA usually like 40mA etc! but I would rather not use them at all if its going to read wrong or be unsafe

ataradov · « **Reply #18 on:** July 13, 2018, 04:43:52 am »

200A? You might as well replace them with a nail.

The problem is not your intent. Fuses protect the meter from accidents. Lets say you wanted to measure a battery voltage, but forgot to switch the meter from "mA" range. Fresh battery will easily supply 10 A and more. And you just fried the meter.

Your safety here is not as affected, if you don't do anything really stupid, like measuring mains directly.

Cody Turner OKC · « **Reply #19 on:** July 13, 2018, 04:58:31 am »

Quote from: ataradov on July 13, 2018, 04:43:52 am

200A? You might as well replace them with a nail.

The problem is not your intent. Fuses protect the meter from accidents. Lets say you wanted to measure a battery voltage, but forgot to switch the meter from "mA" range. Fresh battery will easily supply 10 A and more. And you just fried the meter.

Your safety here is not as affected, if you don't do anything really stupid, like measuring mains directly.

oh wow, I thought it was 5A (the lowest value I could find for the 440mA fuse.. I know still way to high) the side says FNM-5 then written sideways says Amp, now i just saw the other place where it says 200A 250VAC, not sure why? but the package also says 5A time delay slow blow fuse, and yeah I didnt think about that, its probably better to have no fuse in it there then because if a mistake somehow got made it would mess my meter up, I was only thinking in terms of saftey, thank you

ataradov · « **Reply #20 on:** July 13, 2018, 05:01:12 am »

Quote from: Cody Turner OKC on July 13, 2018, 04:58:31 am

it says 200A 250VAC, not sure why?

My bad. FNM-5 is a 5 A fuse. And 200 A is an interrupting capacity.

Shock · « **Reply #21 on:** July 13, 2018, 05:02:12 am »

If you watch the video resistance check of the mA/uA fuse is a slow blow as he says typically will show as 1K ohm. The 10A is showing an ohm or so (mines even less).

Put the correct fuses in it, and test it then. In the meantime leave them out and don't connect into the current sockets, no accidents.

A hint also never use the multimeter to test for current if you are unsure, otherwise you will just end up blowing fuses. When you know you're expecting say 100mA and want to measure the exact current then you first measure on the 10A range and see it's in a safe range to move to the mA/uA socket to get an accurate measurement.

ataradov · « **Reply #22 on:** July 13, 2018, 05:07:00 am »

I would get properly rated fuses, even if they are not exactly Fluke endorsed. This will ensure relative meter safety. And your safety is ensured by not working on high energy circus.

Also, a set of Fluke fuses costs more than some decent meters. May be pick one of those up as well.

MosherIV · « **Reply #23 on:** July 13, 2018, 07:00:41 am »

Hi.

Well done for doing all that hard work gardening and on scoring a decent meter.

If you want to measure current while you do not have fuses, put a small resistor (eg 10 $\$\Omega\$$ ) in line with the circuit. Then measure the voltage across the resistor, use ohms law to calculate the current ( I = V ÷ R )

I think the 87 has mV range which should help with resolution.
Do not forget to measure the resistance to get accurate results.

Mr. Scram · « **Reply #24 on:** July 13, 2018, 07:31:48 am »

Quote from: MosherIV on July 13, 2018, 07:00:41 am

Hi.

Well done for doing all that hard work gardening and on scoring a decent meter.

If you want to measure current while you do not have fuses, put a small resistor (eg 10 $\$\Omega\$$ ) in line with the circuit. Then measure the voltage across the resistor, use ohms law to calculate the current ( I = V ÷ R )

I think the 87 has mV range which should help with resolution.
Do not forget to measure the resistance to get accurate results.

Good tip. Don't go messing with the wrong fuses.


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Author Topic: fluke dmm, really need help (Read 6739 times)

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