This is the #1 resource for vintage test equipment manuals. Search for “Metex M-4650CR.” They often host multiple revisions, including the schematic.
The Metex M-4650CR stands out among legacy test equipment due to its and hybrid visual layout.
The stands out as a highly resilient, 4½-digit, 20,000-count bench-and-field handheld multimeter legendary for its accuracy and integrated RS232 serial communication. Manufactured by the Metex Corporation , this iconic piece of test equipment has remained a "hot" topic for engineers, vintage electronics restorers, and hobbyists alike.
The keyword tells a story of a technician in the middle of a job. They have an aging but capable bench meter, they need to measure around 12 amperes in a live circuit, and they are rightfully concerned about safety. The PDF is not just a manual—it’s a lifeline for specs, fuse ratings, and thermal limits.
A user searching for “Metex M 4650CR PDF 12 Hot” is likely troubleshooting a scenario where they need to measure , and they are worried about blowing the meter’s fuse or damaging the input jack. They urgently need the PDF to check the meter’s safety ratings (CAT I, II, or III) and the internal fuse type (e.g., 12A/250V fast-blow ceramic). metex m 4650cr pdf 12 hot
In community repair forums like the EEVblog Multimeter Repair Threads, specific pages of the manual are highlighted when diagnosing calibration drifting or hardware faults. 1. Input Impedance and DCV Calibration
When a meter ages, it may begin displaying inaccurate voltages. A classic symptom is reading roughly (e.g., displaying 4V on a known, stable 5V rail). This behavior points to an impedance breakdown. If the internal resistance drops below 10MΩ, it loads down the circuit under test, skewing the internal voltage dividers. Why Input Impedance Drops over Time:
Operating a 20,000-count meter requires careful setup to avoid blowing internal safety fuses or damaging the internal logic board.
involves page 12 of the manual. Users frequently ask about the , which is rated at a stable 10M ohm across all ranges. Why "12 Hot" Matters This is the #1 resource for vintage test equipment manuals
If you are still experiencing issues with your meter's input impedance, I can help you find a service manual or suggest specific cleaners for the rotary switch. Share public link
To interface the M-4650CR with a PC:
The service manual PDF shows the PTC, spark gaps, and transient suppression diodes. For a “hot” (live) 12V system, you need to know if the meter can survive a voltage spike (e.g., load dump in a car).
Here’s a helpful breakdown based on available information about the Metex M 4650CR: The stands out as a highly resilient, 4½-digit,
: Locks transient peaks or freezes the current reading on the screen.
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The Metex M-4650CR is a name that sparks recognition among seasoned electronics enthusiasts, engineers, and technicians. Manufactured by Metex Corporation of Seoul, South Korea, it is a testament to the era when robust, feature-rich multimeters were built to last. It’s not simply a current-measuring tool; it’s a comprehensive, handheld device that covers a wide range of measurement tasks, from basic voltage checks to advanced component testing. The “CR” designation likely signifies the presence of the RS-232C interface, a key feature that set it apart from more basic models. Its 4½-digit display provides a resolution of 19,999 counts, offering excellent precision for its time.
| Function | Range | Resolution | Accuracy | |---|---|---|---| | | 200 mV | 10 µV | ±(0.05% + 3 digits) | | | 2 V | 100 µV | ±(0.1% + 5 digits) | | | 20 V | 1 mV | | | | 200 V | 10 mV | | | | 1000 V | 100 mV | | | AC Voltage (VAC) | 200 mV | 10 µV | ±(0.5% + 10 digits) | | | 2 V | 100 µV | | | | 20 V | 1 mV | | | | 200 V | 10 mV | ±(0.8% + 5 digits) | | | 750 V | 100 mV | | | DC Current (ADC) | 2 mA | 100 nA | ±(0.3% + 3 digits) | | | 200 mA | 10 µA | ±(0.5% + 3 digits) | | | 20 A | 1 mA | ±(0.8% + 5 digits) | | AC Current (AAC) | 2 mA | 100 nA | ±(0.8% + 10 digits) | | | 200 mA | 10 µA | ±(1.0% + 10 digits) | | | 20 A | 1 mA | ±(1.2% + 15 digits) | | Resistance (Ω) | 200 Ω | 0.01 Ω | ±(0.2% + 10 digits) | | | 2 kΩ | 0.1 Ω | ±(0.15% + 3 digits) | | | 20 kΩ | 1 Ω | | | | 200 kΩ | 10 Ω | | | | 2 MΩ | 100 Ω | ±(0.5% + 5 digits) | | | 20 MΩ | 1 kΩ | | | Capacitance (F) | 2000 pF | 0.1 pF | ±(2.0% + 20 digits) | | | 200 nF | 10 pF | | | | 20 μF | 1 nF | ±(3.0% + 30 digits) | | Frequency (Hz) | 20 kHz | 1 Hz | ±(2.0% + 5 digits) | | | 200 kHz | 10 Hz | | Note: Accuracies for DC Voltage at 200mV/2V/20V/200V are from the manual; for 1000V range, accuracy is ±(0.1% + 5 digits). AC specifications are as shown; for 200mA AC range, accuracy is ±(0.8% + 10 digits) with an additional specification of ±(1.0% + 10 digits) for the 200mA range; for 20A AC range, accuracy is ±(1.0% + 10 digits). Many accuracies are given as "% of reading (rdg) + number of digits".