Fluke 77 Series III Troubleshooting
The multimeter is not displaying the measurements correctly
The Fluke 77 Series III Multimeter's measurements are not displaying in your desired units - for example your voltage measurements are in kilovolts (kV) rather than Volts (V).
If your multimeter is not displaying measurements in the correct units, you can set the multimeter to a different range by repeatedly pressing the "RANGE" button. You can also set the multimeter to automatic ranging by pressing "HOLD" twice, if Hold is not already enabled. If Hold is enabled, you can set automatic ranging by pressing "HOLD" once. The Hold mode takes and displays stable measurements for functions.
The multimeter is not powering on
The Fluke 77 Series III Multimeter is showing no signs of power in the display even after the dial is turned to a measurement mode.
The battery is dead
If the multimeter does not turn on, its 9V battery may be dead and you may need to replace it.
The PCA is damaged
If the multimeter is not powering on, the PCA may be damaged. As a last resort, you may have to replace the PCA.
The multimeter is displaying an error message
Your Fluke 77 Series III Multimeter displays an error message instead of correctly measuring.
The battery is low
If your multimeter is displaying an error message, the battery may be weak. A weak battery may cause every element on the LCD Display to darken. The message "0L" could also display if the battery is weak. You will have to replace the 9V battery.
The PCA is damaged
If your multimeter is displaying an error message, the multimeter may be fundamentally damaged. The PCA needs to be replaced if changing the battery does not work.
There are no error messages, but the multimeter is not measuring
Your Fluke 77 Series III Multimeter is powered on, but after you connect your leads into the input holes of the multimeter and connect the probes to the desired part of your circuit, the LCD Display does not change.
Your leads are in the wrong locations
If the multimeter is not measuring and there are no error messages, you might have the leads in the wrong sockets on the multimeter. For the Fluke 77 Series III Multimeter the black labelled "COM" input (bottom right) is always ground for any type of measurement. However, the red labelled input with the "V" and Omega symbol (top right) is the positive input only for voltage, resistance, and diode measurements. The 300 mA input (top left) is the positive input for any current below 300 mA and the 10 A input (bottom left) is the positive input for any current below 10 A. Remember to use the minimum current value slot necessary, and also to never exceed the device's capabilities.
The dial is in the wrong position
If the multimeter is not measuring and there are no error messages you may have set the dial to the wrong measuring mode. For example if you want to measure 100 mA of DC current, you should have the dial set to the last measuring option from "off". You may have the input leads in the correct spots (300 mA and COM), but if you have the dial set to DC Voltage (second option from off) or AC Current (second to last option), you will measure incorrectly or not at all.
The leads are dirty
If the multimeter is not measuring and there are no error messages, the input ports or leads could be dirty. You can clean the multimeter according to the instructions on the Fluke 77 Series III Multimeter Service Manual.
The leads are broken
If the multimeter is not measuring and there are no error messages, the multimeter leads may be broken and you will need to get a new pair. Make sure to only use leads with the multimeter that are accepted for use with it according to the Fluke 77 Series III Multimeter Service Manual.
One or both of the fuses are broken
If the multimeter is not measuring and there are no error messages, at least one of your multimeter's fuses may be broken and you will need to replace any broken fuse(s). Remember: never use the Fluke 77 Series III Multimeter to measure AC/DC current greater than maximum current allowed for the input port you are using.
One or more segments of the multimeter's readout is not displaying
You turn on your Fluke 77 Series III Multimeter and use it to measure a value in a circuit. The multimeter seems to be working, but the display is not showing the entire value. Segments, or whole characters, of the output are missing from the seven segment LCD display.
The LCD is damaged
If a segment of the multimeter measurements are not displaying, the LCD (display) on your Fluke 77 Series III Multimeter may be partially or fully damaged. You will need to replace the LCD.
The buttons are not working
You try to press the RANGE or HOLD button on your Fluke 77 Series III Multimeter, but one or both of them do not do anything.
The buttons are jammed
If the buttons are not working, the buttons may be jammed and you will need to reinstall or replace them.
The input on the PCA is broken
If the buttons are not working, the input/output functionality of your multimeter's PCA may be broken. You will need to replace the PCA.
The dial is not working
You try to turn the dial of the multimeter to turn it on, off, or change a measurement mode, but the dial is not changing the display, changes the display incorrectly, or is not working in some other way.
The dial is jammed
If the dial is not working, the dial is jammed and you will need to reinstall or replace it.
The dial is not changing display
If the dial is not working, the display may be broken. You will need to replace the LCD.
The input on the PCA is broken
If the dial is not working, the input/output functionality of the PCA may be broken. You will need to replace the PCA.
None of the above
None of the above categories matches your problem, or you tried one of the above fixes and it did not work.
There are a number of resources that you can still use to diagnose or fix your Fluke 77 Series III Multimeter. Consult the Fluke 77 Series III Multimeter Manufacturer Support Materials for more repair advice and guides on part replacement, testing, and cleaning. The Fluke 77 Series III Multimeter Instruction Sheet is another useful resource for understanding how to use the multimeter and fix its basic issues. If all else fails, you can find the Fluke 77 Series III Multimeter Manufacturer Device Page for more information and to contact Fluke Corporation.