Mastering the Metex M-4650CR Digital Multimeter: Specifications, Repair Tips, and Using the Official PDF Manual
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The has an active and highly detailed thread dedicated to the Metex M-4650CR, including discussions about its accuracy, age, and repair. Searching for "Metex m4650cr" on EEVblog will lead you to a treasure trove of user experiences, troubleshooting tips, and solutions to common problems. You can also find discussions on other electronics forums dedicated to older test equipment, where owners share calibration data and repair logs. digits, max reading of 19,999 with a 41-point
digits, max reading of 19,999 with a 41-point analog bar graph for observing rapidly changing signals. Up to 1000V DC and 750V AC. DC/AC Current: Up to 20A (with a dedicated 20A terminal). : The meter streams a 14-byte ASCII string
: The meter streams a 14-byte ASCII string containing the function mode, polarity, measured value, and unit whenever the front-panel COMM switch is engaged. 📋 Comprehensive Technical Summary Parameter / Feature Operational Value Diagnostic Notes Max Display Count 20,000 Counts (4½ Digits) Ideal for precision calibration work DCV Input Impedance 10 Megohms (10MΩ) Outlined on Page 12 of the manual Common Failure Mode 80% Voltage Reading Deficit Caused by contamination or rotary switch corrosion Data Logging Support Supported via sigrok driver Requires RS232 to USB adapter connection
Check the high-precision metal film resistor network situated right next to the input jacks. Look for cracked solder joints or discolored varistors/PTCs meant to absorb over-voltage spikes. If an over-voltage event occurred in its past, these components may fail into a semi-conductive state, permanently bleeding current away from the ADC. 💻 Logging Data via the RS232 Interface