The Keysight  U1282AU1282A Multimeter is an awesome instrument loads of features great resolution(59999 great accuracy(0.025 spectacular battery life(up to 800 hours and phenomenally rugged(3 m drop and IP67 U1282A

Dave Jones has done a monumentally punishing torture test of this meter. Here he is tossing it out the window of a car driving at 88 km/hr and it still worked fine afterwards.

CarToss

If you want check out just how spectacularly rugged this meter is see his torture test video here.

Maybe Keysight should make a cell phone this rugged - I know people who could use one.

 

This road test segment provides a peek inside. I have to admit I'm in no hurry to take my precious meter apart, but I wanted to include a section on what is inside to make the road test more complete, so I scrounged the internet for some images and will add my own description notes.

The meter is waterproof and all controls reflect this design objective, none the less, they all provide good tactile feedback with enough spacing to allow operation with gloves on. The hinged stand is part of the inner hard plastic case, so it will still stand up fine with the protective rubber shell removed.

U1282A_back-off

Removing the 6 self-tapping case screws allows the back, which houses the batteries, to come off, revealing the back of the rotary switch and a couple of large high voltage, high current fuses.

back closeup

In this close-up of the terminal area you can see the lengths they went to to protect against high voltage and current. The PCB has physical slots and metal shields to prevent arcing across the surface. There are perhaps 5 positive temperature coefficient (PTC) resistors (large green or black components in the input area) that will increase their resistance if they experience high current.

range resistorsThe white brick here looks like a nice 100nf Kemet Evox metallized polyester capacitor 630 V. The metal cover behind it shields the range-selection ceramic resistor network of temperature coefficient matched resistors. The spring connects to a battery terminal.

vsense

Over at the right is the V-Sense circuit to detect high electric fields.

inductor

Zooming in - this inductor (L1) has been gooped up with RTV, probably to make it better able to survive high g shock loads. Inductors can be relatively large with lots of heavy iron and copper in them and they tend to break before most other types of component.

CCA sideBIn this overview it looks like there are about 15 chips with more than 4 pins. A crystal is also visible.

HY3131

The 48 pin LQFP chip is a very capable Hycon HY3131 DMM analog front end.

keypad

This image shows the back of the front cover with the rotary selector in the middle. The silicone rubber keypad has 12 carbon-silicone contact pucks.

CCA top

The top of the CCA does not have much circuitry but you can see more clearly how extensive the isolation cut-outs are, and you can see the hard gold contacts for the rotary switch. It looks like the keypad contacts use the same contact finish.

GDTs

Just above the rotary contacts are a couple of gas discharge tubes (GDTs) to protect against high voltage. On some of the other images you can see there is actually a slot right under each tube to prevent arcing on the card.

78F0485

With the LCD off you can see the rows of pads that connect to the LCD zebra connectors. The main CPU and display driver chip is a Renesas D78F0485 which is an 8 bit CPU with a 16 bit A/D converter. You may be able to deduce the clock rate from the crystal on the other side.

 

In summary, the teardown shows the meter is very well designed and very well built.

 

The next installment will cover some applications that are of interest to me.

 

Links to other installments of this road test:

unboxing

component and DC voltage measurements exploration

waveform measurements exploration

teardown research

applications exploration - component sorting

applications exploration - water level measurement

applications exploration - sensor datalogging

formal road test link