Teardown, Repair and Analysis of an Anritsu MS2721A 7.1GHz Portable Spectrum Analyzer

In this episode Shahriar takes a look at an Anritsu MS2721A portable spectrum analyzer which does not completely boot up. After displaying the message “Application Running!” the unit no longer advances to the main measurement screen. After intentionally corrupting the firmware, a system menu is observed.

During the teardown of the unit, various DC-DC converters are examined along with a basic overview of the Linear Technologies DC-DC converter datasheet. The main problem is traced to a faulty SRAM IC. After replacing the IC the unit completes the boot process. Various simple experiments are performed to ensure the unit’s functionality and correct operation.


  1. Marcelo says:

    Hi Shahriar.
    Needless to say that this is another GREAT video.
    I have one MS2721A just like yours and just recently I noticed that it is reading 30dB lower that the actual input level. In other words, with a 0dBm signal at its input the display shows only -30dBm no matter what frequency I am using. My first thought about this issue is that something is bad on the RF section (maybe one attenuator got “stuck”) and I was wondering if you have any data to share with me. Actually what am I looking for is some IF level information versus input signal. I guess I could isolate the problem either in the RF section or in the IF/AD section.
    I have been looking for more information on the internet (including some schematics or block diagrams) but I only found a Service Manual that doesn’t tell what we want to know (don’t no why am I surprised with that!!!).
    Thanks for any information you can share with me.

  2. robert rannin says:

    great video as always. as an old timer, we would have hosed the board with ‘freeze mist’ until white and snowy, then apply power. the ‘shorted’ chip thaws first. thermal cameras were a laboratory luxury, not readily available.

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