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This post is for the interested reader, who would like to know a easier way of troubleshooting electronics in his Generator.
Many many Moons ago, Incandescent Light Bulbs served as visual indicators to verify correct operations of a apparatus, indicate faults and aide in troubleshooting problems.
The Fault Indicator Panel is one of those Dinosaurs from days long long gone.
The first LED's, short for Light Emitting Diodes, started to appear in industrial control products in the early 1970's
Due to their much smaller size and significant cost savings vs. the incandescent miniature light bulbs, they started to be used extensively on open Circuit Boards as you encounter them in many Generators.
LED's also require less or no software to be written, as in comparing fault and status systems which employ LCD's, short for Liquid Crystal Displays.
Even with our today's technology, smart phones, OBD II, Engine System Managements etc which can communicate with devices via CAN Bus and sometimes MOD Bus, the LED's are here to stay.
Now, how does this work then?
1. LED's usually have a Legend next to them, either on the Circuit Board itself (small letter's or numbers, may require magnifying glass to read) or on the enclosure.
LED's which are labeled:
DC Power, 24V, 24V OK, 12V, 12V OK, 5V, 5V OK, 3.3V, 3.3V OK etc should come on whenever the required operating voltage is applied to such a device - These LED's can verify quickly if all required Voltages are present without the need of a Voltage Meter
Other LED's will come on at specific times or conditions and their functionality is usually explained in the TM's
One rather rare exception in this is the LED used on GAG Governor Controllers which indicate the functioning of the MPU
Once a GAG controlled Generator Starts and the MPU is electrically OK, then the MPU LED will illuminate.
However, on GAG Governor Controller's the illumination, meaning intensity of the emitted green light, is directly proportional to the output Voltage of the MPU, which is in most cases between 1 V to 3.5 V AC from the MPU
The MPU LED, with an additional Diode like a 1N4001 etc., will rectify this very low AC Voltage
In this case, a 1 V AC will be around 0.7V DC (Half Wave Rectifier) which is not enough to drive the LED, which needs normally app. 1.2V to illuminate. Intensity then depends on actual current supplied.
In most manuals and from experience of other Board members, a MPU output Voltage of 2.5 VAC is recommended by adjusting the MPU
As higher this MPU AC Voltage is, the more intense the green MPU LED on the GAG Governor Controller will be.
A trained technician can therefor judge the approximate AC Output Voltage of the MPU by just looking at the intensity of the green MPU LED without ever taking one measurement with a AC Volt Meter
Hope this helps someone!
Many many Moons ago, Incandescent Light Bulbs served as visual indicators to verify correct operations of a apparatus, indicate faults and aide in troubleshooting problems.
The Fault Indicator Panel is one of those Dinosaurs from days long long gone.
The first LED's, short for Light Emitting Diodes, started to appear in industrial control products in the early 1970's
Due to their much smaller size and significant cost savings vs. the incandescent miniature light bulbs, they started to be used extensively on open Circuit Boards as you encounter them in many Generators.
LED's also require less or no software to be written, as in comparing fault and status systems which employ LCD's, short for Liquid Crystal Displays.
Even with our today's technology, smart phones, OBD II, Engine System Managements etc which can communicate with devices via CAN Bus and sometimes MOD Bus, the LED's are here to stay.
Now, how does this work then?
1. LED's usually have a Legend next to them, either on the Circuit Board itself (small letter's or numbers, may require magnifying glass to read) or on the enclosure.
LED's which are labeled:
DC Power, 24V, 24V OK, 12V, 12V OK, 5V, 5V OK, 3.3V, 3.3V OK etc should come on whenever the required operating voltage is applied to such a device - These LED's can verify quickly if all required Voltages are present without the need of a Voltage Meter
Other LED's will come on at specific times or conditions and their functionality is usually explained in the TM's
One rather rare exception in this is the LED used on GAG Governor Controllers which indicate the functioning of the MPU
Once a GAG controlled Generator Starts and the MPU is electrically OK, then the MPU LED will illuminate.
However, on GAG Governor Controller's the illumination, meaning intensity of the emitted green light, is directly proportional to the output Voltage of the MPU, which is in most cases between 1 V to 3.5 V AC from the MPU
The MPU LED, with an additional Diode like a 1N4001 etc., will rectify this very low AC Voltage
In this case, a 1 V AC will be around 0.7V DC (Half Wave Rectifier) which is not enough to drive the LED, which needs normally app. 1.2V to illuminate. Intensity then depends on actual current supplied.
In most manuals and from experience of other Board members, a MPU output Voltage of 2.5 VAC is recommended by adjusting the MPU
As higher this MPU AC Voltage is, the more intense the green MPU LED on the GAG Governor Controller will be.
A trained technician can therefor judge the approximate AC Output Voltage of the MPU by just looking at the intensity of the green MPU LED without ever taking one measurement with a AC Volt Meter
Hope this helps someone!
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