Author Archives: modemhead

About modemhead

Fixologist and multimeter junkie.

Fluke Banana Jack Repair

Posted on July 25, 2013 by modemhead

Ever bought a set of those cheap Chinese-made multimeter probes?  They probably had some little plastic inserts in the banana plugs.  For what reason I’m not sure, maybe to keep the safety shroud around the plug from deforming.  Don’t toss … Continue reading →

Posted in How-To, Repair | Tagged , , | 8 Comments

Tektronix DMM912 Teardown

Posted on May 16, 2013 by modemhead

Tektronix may be known best for their industry-leading oscilloscopes, but they also sell other test equipment, including a line of handheld multimeters in the 1990s. The model documented here is a DMM912, part of a series of multimeters that included … Continue reading →

Posted in Teardown | Tagged , | 7 Comments

Beckman LCD Assembly Repair

Posted on April 18, 2013 by modemhead

The basic Beckman multimeter design that seems to apply to many of their 3½ digit models from the late 1970s onward include an LCD/processor chip assembly held together by various plastic parts that simply clip together.  The later Wavetek-branded models … Continue reading →

Posted in Modifications, Repair | Tagged , , | 46 Comments

Fluke 23-III DMM Repair

Posted on March 24, 2013 by modemhead

The first two generations of the popular 70-series Fluke handheld DMMs included the 21 and 23 models, which were the same as the 75 and 77 respectively, except their cases were safety yellow instead of the usual dark gray.  The … Continue reading →

Posted in Repair | Tagged , , , | 12 Comments

Beckman Industrial HD140 Multimeter

Posted on March 16, 2013 by modemhead

The HD140 digital multimeter from Beckman Industrial is another in the “heavy-duty” series, very similar to the HD110 in a previous article.  Unlike the HD110 however, this is a 20,000-count 4½ digit model with RMS-responding AC capability. Unfortunately I can … Continue reading →

Posted in Repair, Teardown | Tagged , | 16 Comments

HP 3468A Battery Replacement

Posted on March 7, 2013 by modemhead

The HP 3468A multimeter repaired in the last post uses something called “closed-case” or software calibration.  Instead of making physical adjustments to controls inside, calibration involves applying known reference levels and having the meter store calibration constants.  These are essentially … Continue reading →

Posted in How-To, Repair | Tagged , | 23 Comments