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Old 04-26-2015, 12:19 PM   #1
jasonbay13
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Default Digital Multimeters (Also Brymen BM869 repair)

So i'm looking for a new dmm to replace my cheap craftsman. preferrably one that is:
Nice to use, capacitance of at least 5000uf, and true rms.
bonus if it has a db scale and useful extras.
Price is not important (just keep it under 500).

I was looking at either a klein 2300, fluke 117, or fluke 87v.
though i have heard klein is supposed to be coming out with new meter line soon? and i dont know of any other brand besides uni-t or mastertech.

any suggestions what to get? what not to get?
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Old 04-26-2015, 12:45 PM   #2
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Default Re: Digital Multimeters

desktop? portable?

for desktop there is some real impressive kit from Rigol.
http://www.rigol.com/prodserv/Digital%20Multimeters/

for portable,
if your doing something where it could get broken - UNI-T.
if you want he best then look at something like Agilent.
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Old 05-30-2016, 04:45 PM   #3
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Default Re: Digital Multimeters

looks like i should have just bought the fluke. killed my $250 bm869 trying to measure the voltage of a step-up transformer. still dont know the voltage but i thought it could handle over 1kv without exploding.

anyway, since i've no longer a decent meter, what should i get? some of those harbor freight meters so i dont feel like driving off a cliff when i fry one or something more expensive so when i kill it i can curl up and start crying myself to sleep hoping it will all be better when i wake up?

stupidity is ridiculously expensive
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Old 05-30-2016, 05:23 PM   #4
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Default Re: Digital Multimeters

Quote:
Originally Posted by jasonbay13 View Post
killed my $250 bm869 trying to measure the voltage of a step-up transformer. still dont know the voltage but i thought it could handle over 1kv without exploding.
If you would like to take a shot of fixing the BM869, I suggest with starting with some clear focused pictures of the pcb.

I can also make suggestions if you want to try and fix it. If not, send me a PM as I would be interested in possibly purchasing your dead BM869.
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Old 05-30-2016, 06:01 PM   #5
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Default Re: Digital Multimeters

I've had good luck with my UEI dm393. UEI is owned by Klein tools, so it's good stuff. No Fluke, but a lot cheaper with comparable build quality.
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Old 05-30-2016, 06:18 PM   #6
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Default Re: Digital Multimeters

Okay, if volts and ohms are not working, you may have blown one or more of the input protection components.

Assuming your meter looks like this (pictures from eevblog)

https://www.flickr.com/photos/eevblo...7632878242654/

you can test the components in-circuit with another meter. Remove the battery from your BM869.

1) The three SPG (blue components) are your spark gaps. With another meter, they should each measure infinite resistance (or 0L).

2) The two grey components in the black heatshrink are PTCs (just right of the 3 blue spark gaps). They should each measure around 1k ohm.

3) The two resistors (grey color body with brown band) just right of the PTCs should be your power resistors. I believe they should measure around 1k ohm.

4) I'm not 100% sure what the component in black heatshrink (marked CSA) is, but I'm guessing it could be a fusible resistor. It should measure around 1k ohm.
Attached Images
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Last edited by retiredcaps; 05-30-2016 at 06:38 PM..
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Old 05-30-2016, 06:19 PM   #7
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Default Re: Digital Multimeters

J
Ever think to look at some real instruments from 'days gone by'.

For example I use an HP 3456A for fancy stuff on the bench.
Six and a half digits impresses the heck out of the neighbors.
I can connect it to a D battery and watch the cell decay one micro volt at a time. Has a killer AC RMS section and a very cool four wire ohm's ability.

Not at all portable but one hell of an instrument.
http://www.ebay.com/itm/HP-3456A-Dig...gAAOSwfY9XP70P

A more realistic tool would be this.
Fluke 8600A, a pro tool that is hard to kill.
http://www.ebay.com/itm/Fluke-8600A-...gAAOSwoydWorsU

The Fluke 8050 ain't bad either.
http://www.ebay.com/itm/Fluke-8050A-...AAAOSwYmZXLoNB

If your willing to look to the past, there is a lot of good gear out there for cheap.

My regular meter, is an old Fluke 77, had it for years.
Looks a lot like this one.
http://www.ebay.com/itm/Fluke-77-Han...0AAOSwZ8ZXBBA7

The portable instruments show up at pawn dealers all the time, so you might score a deal. Bring some batteries with you, leads and a couple of test parts to check it out.

Much luck.
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Old 05-30-2016, 06:24 PM   #8
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Default Re: Digital Multimeters

Quote:
Originally Posted by ratdude747 View Post
I've had good luck with my UEI dm393. UEI is owned by Klein tools, so it's good stuff.
Some of UEI and Klein meters are made in Korea by Fine Instruments.

http://www.finest.co.kr/pi.html#hd

http://www.eevblog.com/forum/testgea...-meter-review/
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Old 05-30-2016, 08:27 PM   #9
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Default Re: Digital Multimeters

Quote:
Originally Posted by retiredcaps View Post
Some of UEI and Klein meters are made in Korea by Fine Instruments.

http://www.finest.co.kr/pi.html#hd

http://www.eevblog.com/forum/testgea...-meter-review/
Yeah, so what? The build quality is just like the two meters mentioned. Honestly the "bad hand solder job" isn't all that bad IMHO if that is no-clean flux... last time I had mine open I didn't see any corrosion so it must be OK.

That said the linked klien meter has IDENTICAL accessories... different brand, same guts.

I've beat the hell out of mine... the probes have seen better days (but they're like $10 a set on ebay, with the screw-on alligator clips included) but other than scuffs and dirt my DM393 still works great. I'd take it over a meh build quality uni-T any day.

I've seen stuff made in china have great build quality and stuff made in USA be complete BS. Not to say that there isn't a trend (there generally is) but just because it says "made in korea" makes it automatically junk.
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Old 05-30-2016, 09:25 PM   #10
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Default Re: Digital Multimeters

Quote:
Originally Posted by retiredcaps View Post
1) The three SPG (blue components) are your spark gaps. With another meter, they should each measure infinite resistance (or 0L).
I should have said SPG/MOVs.
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Old 05-30-2016, 09:29 PM   #11
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Default Re: Digital Multimeters

Quote:
Originally Posted by ratdude747 View Post
Yeah, so what?

Not to say that there isn't a trend (there generally is) but just because it says "made in korea" makes it automatically junk.
I don't know why you always assume people have a hidden agenda in every statement. There was no subtext in my factual statement. I didn't say it was junk or it was good.

I just stated a fact that it was Made in Korea and that Klein and UEI get Fine Instruments to make it for them.
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Old 05-30-2016, 09:39 PM   #12
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Default Re: Digital Multimeters

Quote:
Originally Posted by retiredcaps View Post
I don't know why you always assume people have a hidden agenda in every statement. There was no subtext in my factual statement. I didn't say it was junk or it was good.

I just stated a fact that it was Made in Korea and that Klein and UEI get Fine Instruments to make it for them.
Sorry about that. It came off sounding that way when I first read it.
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Old 05-30-2016, 09:53 PM   #13
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Default Re: Digital Multimeters

Quote:
Originally Posted by jasonbay13 View Post
still dont know the voltage but i thought it could handle over 1kv without exploding.
Any multimeter regardless of brand or country of origin, when subjected to enough abuse (high voltage in your case), should fail safely and protect the user. Secondarily, it should protect itself from catastrophic failure.

The better meters will have input protection. See

https://www.youtube.com/watch?v=zUhnGp5vh60

Over at eevblog, you will see lots of people asking for help with Fluke meters that have been subjected to abuse. Luckily, we have been able to fix many of them because the input protection components did their job and protected the user and the meter.

Here is an excellent write up by modemhead, also a member here.

http://mrmodemhead.com/blog/fluke-87-fusible-resistor/

The lower quality made/designed meters, regardless of price, will have little to no input protection and the main IC gets fried.
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Old 05-30-2016, 10:18 PM   #14
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Default Re: Digital Multimeters

other than the guy the other day with his 500v UNI-T that correctly read 1.2Kv on his fence charger wihout damage!!
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Old 05-31-2016, 04:37 AM   #15
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Default Re: Digital Multimeters

off to work now, but the right side of the case from the screw to screw seems to be stuck, maybe it melted on the inside. should i just apply more force?
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Old 05-31-2016, 11:02 AM   #16
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Default Re: Digital Multimeters

Quote:
Originally Posted by jasonbay13 View Post
off to work now, but the right side of the case from the screw to screw seems to be stuck, maybe it melted on the inside. should i just apply more force?
I doubt it is melted or fused inside, but according to the manual and Dave's teardown

http://www.hellermanntyton.co.za/dow...multimeter.pdf

there are 4 captive screws with an o-ring seal and deep recessed case walls. You may just need more force. Note the screws appear very long in length.

"Fuse replacement:
Loosen the 4 screws from the case bottom. Lift the end of the case bottom nearest the
input jacks until it unsnaps from the case top. Replace the blown fuse(s). Replace the
case bottom, and ensure that all the gaskets are properly seated and the two snaps on
the case top (near the LCD side) are engaged. Re-fasten the screws."

Dave's review. See starting around 16 minute mark

https://www.youtube.com/watch?v=tXu0lsOjvDs

Last edited by retiredcaps; 05-31-2016 at 11:07 AM..
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Old 05-31-2016, 06:12 PM   #17
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Default Re: Digital Multimeters

just got it popped open, it was indeed melted. about a penny size chunk of the plastic has been molded together. really surprised it didnt just snap

4 green resistors (large) are melted and welded together and a ptc has completely destroyed. r76 looks like it has some charring around it. one of the blue movs has a dark mark at the top. the board underneath the resistors is crispy looking but might be able to bodge-fix.

pics soon

Last edited by jasonbay13; 05-31-2016 at 06:23 PM..
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Old 05-31-2016, 06:28 PM   #18
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Default Re: Digital Multimeters

Quote:
Originally Posted by stj View Post
other than the guy the other day with his 500v UNI-T that correctly read 1.2Kv on his fence charger wihout damage!!
It's 1.2kV
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Old 05-31-2016, 06:41 PM   #19
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Default Re: Digital Multimeters

pics..........
Attached Images
File Type: jpg bm869s34.jpg (451.5 KB, 38 views)
File Type: jpg bm869s35.jpg (760.4 KB, 38 views)
File Type: jpg bm869s36.jpg (637.8 KB, 38 views)
File Type: jpg bm869s37.jpg (538.7 KB, 36 views)
File Type: jpg bm869s38.jpg (374.4 KB, 28 views)
File Type: jpg bm869s39.jpg (522.6 KB, 31 views)
File Type: jpg bm869s40.jpg (507.8 KB, 34 views)
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Old 05-31-2016, 10:43 PM   #20
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Default Re: Digital Multimeters

Quote:
Originally Posted by jasonbay13 View Post
just got it popped open, it was indeed melted. about a penny size chunk of the plastic has been molded together. really surprised it didnt just snap
I have seen some abused meters, but this one is in the top 5.

Quote:
4 green resistors (large) are melted and welded together and a ptc has completely destroyed. r76 looks like it has some charring around it. one of the blue movs has a dark mark at the top. the board underneath the resistors is crispy looking but might be able to bodge-fix.
If you are willing to put in 1 hour work, I suggest removing all 4 power resistors (green), 2 PTCs and 3 MOVs. No need to measure or test the components. They are all likely bad just by looking at the pictures.

After removing all these components, scrub the entire area with 91% IPA using a clean toothbrush. Scrub until all the carbon residue is gone.

After it has been cleaned and dried, please post pictures so we can assess the damage.

If the damage looks minimal, we can, temporarily, put in regular 1k ohm resistors for the 4 power resistors and 2 PTCs. For testing, we do not have to put in any MOVs.

So with 6 temporarily 1k ohm resistors, we can power up and see if volts and ohms work. If it works, then we can order proper replacements.

PS. Post a picture of R76 and measure it in-circuit.
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