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Old 08-29-2011, 10:08 AM   #1
dumpystig
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Default Bench multimeter - Fluke 8842A

Waiting on this meter to arrive in the next few days. Used but in excellent nick.
It doesn't have the TRMS AC Option -09 board fitted so I'm wondering if anyone has a spare board for sale.

Also does anyone have experience using this meter (or similar 8xxx series) who could give me any pointers to its use, tips, precautions etc..
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Old 08-30-2011, 03:36 AM   #2
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Default Re: Bench multimeter - Fluke 8842A

These are excellent meters; although they are rather deep.
I have used the 8840A version.
The main problem is the display tends to dim with age.
The AC board can be a pain to find if your DVM doesn't come with it.
It might be worth asking on the Fluke Yahoo group.

http://tech.groups.yahoo.com/group/Fluke_DMM

Last edited by Professor Peach; 08-30-2011 at 03:39 AM..
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Old 08-30-2011, 04:41 AM   #3
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Default Re: Bench multimeter - Fluke 8842A

Yeah, deep is an understatement!!! 14.6" to be exact. I know about the fluorescent displays, they tend to fade or become foggy if they've had a life of being turned on for very long periods - but from the pics I've seen this display is solid, bright and consistent. The overall condition looks excellent, should be delivered tomorrow so I will soon find out.
I've already found a member on another forum who has one of these boards; just PM'd him, awaiting a reply .

What was your experience of the 8840? Any tips you may have are welcome.

Thanks for the link, gona have a look over there now
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Old 08-30-2011, 08:53 PM   #4
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Default Re: Bench multimeter - Fluke 8842A

Looks like I'll have the board I'm after pretty soon. Great guy in New Zealand has one that he's gona ship over to me. This internet/WWW malarkey is just fucking ace
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Old 08-31-2011, 09:41 AM   #5
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Default Re: Bench multimeter - Fluke 8842A

Even better...

Meter was delivered this afternoon, excellent nick as I thought, but major bonus is that it's got AC -09 board already installed! Best thing is, before I bid I asked the seller if it had this option - he replied no, it didn't, so i got the meter even cheaper.
Yay, happy happy days

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Old 08-31-2011, 12:32 PM   #6
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Default Re: Bench multimeter - Fluke 8842A

Glad you're all sorted.

My thoughts?
Apart from the depth (which for me makes this DVM a non-starter), I find the construction a bit flimsy. These DVMs are/were widely used by the military (the 8840A/AF is a mil spec version). I've seen them on ebay looking like they've been run over by a tank. The handles break off too easily.
The lowest range is only 200mV, the old Fluke standard; a bit pants.
It never happened to me, but I've seen posts on yahoo; people looking for ROM images, etc. It would seem they sometimes forget what they are.

It's worth remembering; the input impedance is very high (something like) 10,000MΩ

All in all, they are excellent meters; I'm sure yours will serve you well.

Last edited by Professor Peach; 08-31-2011 at 12:35 PM..
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Old 08-31-2011, 03:50 PM   #7
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Default Re: Bench multimeter - Fluke 8842A

That's only the AC Range and that number is an upper limit for the range.
The 5.5 digit reads down to .000001v for AC and .0000001v for DC on that one.

We used various Fluke 8xxx models in engineering/machinery spaces in the Navy primarily because they were what was Certified for use on gear in the NUC plants.
Pretty much have to be a klutz to break one in normal use.
They get broke in the military due to unique situations like having to hang onto a ladder while you measure something 10, 20, or more feet up. They are a bit bulky for that but they are what is required.

I have a 8600A which is what I used most often.
It's good to +/-.00001v on both AC and DC and cal-able that far down at least for DC.
Which is good because the spec for some of our PSUs was +/-.00005 vdc.
When you are adjusting one of those pots - don't fart. - You'll be there all day.
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Old 08-31-2011, 05:22 PM   #8
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Default Re: Bench multimeter - Fluke 8842A

Quote:
Originally Posted by Professor Peach View Post
My thoughts?
Apart from the depth (which for me makes this DVM a non-starter), I find the construction a bit flimsy... I've seen them on ebay looking like they've been run over by a tank.
Huh? I've had it totally stripped down in bits tonight - everything is fixed inside a 2.5mm steel chassis which is then enclosed within a thick alumimium casing. Both the front and back plastic panels are really chunky too. I definitely reckon these are built like tanks, especially compared to a lot of the cheaper ~ mid-range meters on the market right now. I do agree the handle could be prone to breaking, but yes you'd still have to be a bit of a klutz.

PCBONEZ is more precise with the specs, these meters are still good dependable kit.
On a side note there are only 6 electrolytics in this meter (5 on the main board, 1 on the IEEE option, all Nippon Chemi-Con) and every one looks like new - not bad for kit that's about 20 years old. In fact everything inside looks new, and the fascia/buttons/casing are all mint.

Quote:
Originally Posted by Professor Peach View Post
All in all, they are excellent meters; I'm sure yours will serve you well.
Yep, I agree. I think I've got a very good deal on a great piece of kit.
Cheers
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Old 09-09-2011, 10:34 AM   #9
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Default Re: Bench multimeter - Fluke 8842A

Quote:
Originally Posted by Professor Peach View Post
These are excellent meters;
The main problem is the display tends to dim with age.
Fluke has owned the multimeter market for years, and for a good reason. I personally wouldn't consider anything else. If the only problem with your meter is a dim display, order a new florescent tube from Fluke and replace it. I've replaced hundreds of these tubes and it is fairly easy. Keep in mind that they operate on about -30 volts which is typically generated by a switching supply. Once again - secondary filters can age on the -30. Also, if you are going to bring things back to life, look at the filaments of the display tube. Those usually operate at about 3 volts AC or DC, coming from dedicated windings on the switching supply - again a possible dry filter on a dc filament line will cause the display to dim. As with many tube designs, the cathodes and filaments are tied together, so expect -30 volts DC on the filaments to ground, in addition to the 3 volts across the the filament terminals themselves. You will only have to do this job once.
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Old 09-09-2011, 02:48 PM   #10
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Default Re: Bench multimeter - Fluke 8842A

Yeah, it's actually 4.5VAC, supplied directly from a dedicated winding on the transformer.
I love this service manual, as well as the schematics it even gives the resistance values of each winding. And I agree about owning the market, although the Agilent meters are up there too.
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Old 10-23-2011, 08:03 AM   #11
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Default Re: Bench multimeter - Fluke 8842A

So, now that you've had a chance to use the meter, how do you like it? Most times looking at a 5-1/2 digit voltage resolution is a bit annoying for standard repair work, but fortunately you can select different resolutions.

I have a suggestion for others who would like a well-built 5-1/2 digit bench meter which may be more affordable and that's the HP3478a. This meter was built in the 80's, has liquid crystal display and comes with true RMS (not as an option). One really great thing is the excellent and complete service manual and general serviceability of the meter. Even though most people prefer a VFD display, an LCD typically doesn't "wear out" after a certain period of time.
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Old 10-23-2011, 01:03 PM   #12
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Default Re: Bench multimeter - Fluke 8842A

The meter is brilliant, I couldn't be more pleased with it

The display suits me fine, AFAICT it's very accurate, and it's built like a tank - I'm pretty confident it will last as long as I do, it really is a solid piece of kit.

Two points that I will mention, not sure what to call them though - not negatives as such, niggles maybe? Physically it's bloody massive, bit of a space hugger when storing it. And current measurement is only 2A max., but I can use one of my handheld DMM's if I need to go up to 10A.
So yeah, it's now my preferred first meter when I'm testing at home. And as I've mentioned earlier in one of my posts the Service Manual is also very detailed, with full schematics (even the transformer winding values are noted) so that's a bonus should the thing ever breakdown.

My rating: 9.5/10
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