Trouble Shooting
43
Pulse stream of
around 53Hz
Keep pushing down one of
Ω, CAPACITOR, AUTO/MAN
buttons
Pulse stream of
around 53Hz
Keep pushing down one of
DCA, CONTINUITY or HOLD
buttons
Negative or positive
pulse stream of
around 268Hz
Control bits going to and
coming from the front panel
Key Matrix Checks
Every button on the front panel can be checked by pressing
them down one by one to see if a short beep can be heard.
Moreover, service personnel can also have the key matrix’s
function checked by monitoring the waveforms on pin 14
to 17 of U202 according to the descriptions of item 8 to 11
listed in the Digital Circuitry Check table above.
Digital Circuitry Checks
Tables 4 to 14 explain almost all the measurement modes
and the ranges’ signal paths set by actuating different
relays. Service personnel can easily get the information
about which scale resistor, relays or shunt resistor should
be used for any given measurement mode and range by
checking these tables for troubleshooting.
Table 4 DCV Signal Switching
Table 4 shows which relay is actuated and which voltage-dividing resistor is
selected for a given DCV measurement range.
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