Fluke 77 II, beep is too weak almost not be able hear


http://wp.me/ph3BR-12o

this was a problem because a multimeter such old, review to label of manufacturing date, it was about 1996.

nEO_IMG_DSCF4195
the beep is too weak and should be found some bad contact or transistor output malfunction.

ok, search Google, to find the service manual of a model stopped production at long time ago, it will be something like treasure hunting, this time is lucky, the service manual and schematic has been there found.

http://elektrotanya.com/fluke_77_75_73_70_23_21_series_ii_multimeter_sm.pdf/download.html

 

In case you want more other model of Fluke product and service manual, I will recommend to search the website owned by Fluke, this 77 II service manual can be found also,

http://en-us.fluke.com/

According to the service manual, beeper (just a raw piece of piezoelectric disk) has nothing to loose but just connected to GND and the BPR1 (pin3) of IC chip U1, the analog processor, so, if IC has malfunction, then the game is over…..or modification ?!
Try, clean the beeper rubber contacts and PCB solder contacts……

nEO_IMG_DSCF4200 nEO_IMG_DSCF4198 nEO_IMG_DSCF4197

yes, it recovered almost loudly as usual, and looks like problem had resolved.

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