Author Archives: modemhead

About modemhead

Fixologist and multimeter junkie.

HP 3468A Bench Multimeter Repair

Posted on February 23, 2013 by modemhead

Hewlett-Packard has built a reputation for quality bench multimeters every bit as impressive as Fluke has for the handheld variety. Nowadays they’re called Agilent, but this unit has the HP nameplate on it, and date codes on the parts inside … Continue reading →

Posted in Repair, Teardown | Tagged , | 23 Comments

Beckman 3020 DMM Repair

Posted on February 15, 2013 by modemhead

Handheld digital multimeters were just beginning to gain popularity in the late 1970s.  Fluke was there of course, but so was Beckman.  This is a Beckman 3020 3½-digit 2000-count model that dates to 1979.  It has the classic Beckman ‘look’ … Continue reading →

Posted in Repair | Tagged , | 59 Comments

DMM Basics – Dual-Slope ADC

Posted on February 8, 2013 by modemhead

This is the first in a series of posts looking at how a digital multimeter actually works.  First a little theory, then later we’ll look at the ubiquitous ICL7106 that basically started the ball rolling on handheld DMMs back in … Continue reading →

Posted in Theory | Tagged | 7 Comments

Nixie Glow

Posted on January 30, 2013 by modemhead

My first ever digital multimeter was a Heathkit IM-1212.  I built it from a kit when I was a teenager (thanks, Dad.)  A whopping 2½-digit, 200-count unit with 1% ± 1 digit basic DC accuracy.  Barely a step up from … Continue reading →

Posted in Teardown | Tagged , | 8 Comments

Fluke 83-III Rotary Switch

Posted on January 24, 2013 by modemhead

It’s a fact that you can repair as many multimeters with a bottle of isopropyl alcohol and some Q-tips (cotton buds), as you can with a soldering iron.  In many cases, malfunctions can be fixed by careful disassembly and cleaning … Continue reading →

Posted in How-To, Repair | Tagged , , | 15 Comments

Yokogawa 7534-03 Multimeter

Posted on January 17, 2013 by modemhead

Japanese equipment maker Yokogawa made handheld DMMs for HP before HP became Agilent.  This 3200 count 3½ digit Yokogawa-branded model is very similar in appearance to the HP E2378A model.  Unlike the HP, this unit adds a high-impedance ‘ADP’ mode, … Continue reading →

Posted in Repair | Tagged | 19 Comments