Fluke 8842A taken apart

[reagle]

I just had to see how this unit is built, so enjoy
Lots of Fluke branded ICs and also things that look like hybrids, standing vertically. Not sure what they are.
The date code on most is 1992, so the meter is about 18 years old and still looking very good.

[alm]

Those white things are probably precision thin film resistor networks. I'm surprised to see only two relays, usually there are more (most of the switching is usually with relays). Apart from this, nothing unexpected. Thanks for the pictures, don't believe I've seen the inside of this one before. Don't recognize the voltage reference (it's not in the familiar ceramic packaging), according to the manual it's the (round) metal can near the Fluke-branded 40-pin DIP IC, U701.

[saturation]

Nice, crafted well in and out of box!

[qno]

 I also have one for years now.

The main reason I bought this is the high impedance of the DC voltmeter.
> 10 Gohm, yes Giga ohm up to the 20 Volt range droping to 10 Meg in 200 V range.

This is nice when measuring on CMOS circuits.

The new one only has a 12V range > 10 Gohm. For me there is no need to get the new 5 1/2 digit DMM sold as Fluke/Tektronix and in the near future maybe Keithley too....

[Fraser]

I have a pair of these multimeters and they are built to last. I bought them after the mistake of buying a UNI-T 804 (big mistake)

I was impressed to find that it uses firmware driven calibration routines, and was even more impressed to discover that my units were still within specification on all modes and ranges 

The fact that Fluke make the service manual available to the general public is also a bonus and, though custom LSI is in use, it is always nice to have a schematic in case the need for a repair arises.

The only weaknesses I am aware of are surface corrosion in the 4mm sockets if the unit has been in damp conditions, and failure of the fast fit retainers that hold the motherboard in place. These retainers only fail due to rough handling of the meter but are quite difficult to remove, and made of brittle plastic. I used 4mm nylon nuts & screws to replace broken retainers.

Great units at quite reasonable prices. 

[reagle]

This one was actually an ebay find for 80 USD, so for me that's a pretty good deal. It does not have option modules installed, but the basic functionality is enough for me. Full service manual with schematics is also a big reason why I tend to get big name used test equipment. Last one was an HP 54645D scope that needed an NVRAM chip with integrated battery replaced. Same thing-built like a tank, and has all service documents available.