Ballast Troubleshooting Procedures
1. Primary Current: To be taken at the ballast with a multi-meter and a clamp-on amps probe. Place clamp around the black wire only. This reading should be at or below the rating of the ballast as indicated on the label. If the total combined footage does not meet the maximum of the ballast's limit, then this reading will be less than stated on the label. If this reading exceeds the rating, then there is either a short in the wiring or the wiring is incorrect. Double-check the actual wiring with the wiring diagram on the label; look for any wires that may be shorted to ground or one another.
2. Primary Voltage: To be taken across the black and white wire. Should be 120 VAC+/-5%. Any deviation from this will cause premature failure of the ballast. If this voltage is low, attempt to locate the reason; make sure that the wire used to supply the circuit is of sufficient size for the distance from the panel and the rated load. Check the voltage at different points in the primary run to find out where the problem may exist.
3. Filament Voltage: To be taken with a multi-meter in the socket from pin to pin. The reading here should be between 3.5 VAC and 4.5 VAC.
If voltage reading is below 3.5:
a) Check for low primary input voltage.
b) Check for shorted filament wires within the sign.
c) Check for the possibly of damaged or defective ballast.
If voltage reading is above 4.5 volts:
a) Check for high primary input voltage.
b) Check for the possibility of damaged or defective ballast.
4. Filament Current: To be taken using a sensitive multi-meter with a clamp on amp probe. Each wire should be checked with the exception of the black wire. The normal reading will be between 0.5 AMPS and 2 AMPS.
If current reading is below 0.5 amps:
a) Check for open lamp filament (defective lamp)
b) Check for improper filament wiring connection causing an open circuit.
c) Check for low primary input voltage.
d) Check for the possibly of damaged or defective ballast.
If current reading is above 2 amps:
a) Check for external short in the filament wiring.
b) Check for incorrect lamp or defective lamp filament (defective lamp).
c) Check for high primary input voltage.
d) Check for the possibly of damaged or defective ballast.
5. Lamp Filament Resistance: To be taken using a multi-meter with standard test probes, the meter should be set to resistance. Reading to be taken between the two pins at the end of the lamp. This test should be performed for both ends of the lamp, and on each lamp in the circuit. The expected resistance should be approximately (0.5 to 1.2 ohm).
a) Resistance greater that this would indicate an open in the lamp filament and the lamp should be replaced.
b) Resistance less than this would indicate a shorted filament and the lamp should be replaced.
6. Open Circuit Voltage: To be taken using a multi-meter with a High Voltage probe. Reading to be taken across the blue and red wire. Reading should be between 300 and 1000 volts depending on ballast model. On Allanson's 696 and 4120 the readings should be taken between the blue/white and red as well as the blue/white and blue, because these are dual circuit ballasts. See the ballast label for specific OCV rating.
If voltage reading is below the rating on label:
a) Check for low primary input voltage.
b) Check for the possibility of damaged or defective ballast.
If voltage reading is above the rating on the label:
a) Check for high primary input voltage.
b) Check for the possibility of damaged or defective ballast.
7. Lamp Circuit: To be taken using a multi-meter with a clamp-on amps probe. Place clamp around lamp while it is lit. Reading should be between 400 and 800 mA, smaller ballasts being at the high end of the range and larger ballasts being at the lower end of the range.
If current reading is below 400 mA:
a) Check for total lamp footage exceeding ballast rating.
b) Check for defective lamp(s).
c) Check for low primary input voltage.
d) Check for the possibly of damaged or defective ballast.
If current reading is above 800 mA:
a) Check for total lamp footage being below ballast rating.
b) Check for defective lamp (s).
c) Check for high primary input voltage.
d) Check for the possibly of damaged or defective ballast.
8. Ground Plane Present?: YES or NO. All ballasts by all manufacturers are designed to be used with starter strips. They assist the ballast at lamp startup in colder weather, or when a ballast is running at maximum load. On single face signs where the lamps are in close proximity to the metallic sign back, strips may not be needed. The only time in troubleshooting where this is an issue, is when lamps only flicker at startup or take a very long time to come to full brightness.
9. Ambient Temperature: This is the approximate temperature within the sign enclosure when the problems occur.
Proper multi-lamp ballast wiring
The most prevalent cause of Multi-Lamp Ballast failure is the incorrect connection of ballast lead wires for lampholders. In order to assure proper installation of Allanson Multi-Lamp Ballasts, all pairs of ballast lead wires (yellow, blue/white, brown, orange, orange/black), which supply two (2) lampholders by utilizing two (2) additional wire jumpers, must be connected as in the correct method diagram.
An additional common cause of Multi-Lamp Ballast failure is improper wiring where less than the maximum numbers of lamps are used with a combination ballast designed for this option. The ballast lead wires not utilized must be insulated individually from each other, from all other leads and from ground. Testing the Current Consumption of a Light or Appliance Make sure that the appliance or whatever that you are about to measure is turned off. If you have all your positive connections made at one common link it may be easiest to break the continuity at this point. Links often have numbers stamped into the brass to identify the wire locations. Simply undo the screws that hold the wire in question. Finger tighten the screws back onto your positive probe, fix an alligator clip onto the negative probe to hold onto the end of the wire that just came out of the link. Once all your connections are secure you can turn the appliance on and check its current consumption. Testing if a light bulb is OK
This test can only be applied to incandescent type light bulbs. Fluorescent lights will not respond to this test. It would be easier in this case to use one of the ohms scales on the meter or to use the continuity function if it has one. To make these functions work the multimeter should have an internal battery.
Some multimeters have a built-in continuity function which often sounds a buzzer. Test this by selecting continuity on the range switch and touching the two probes together. If it buzzes try holding the probes onto the two contacts of the light bulb and see if it buzzes - if it does the light bulb is OK.
Using Ohms (S) for Continuity If you do not have a continuity function on your multi-meter you can use one of the ohms scales. If you select an ohms scale and touch the probes together you should see the needle of an analog meter move right across the scale and a digital meter should change from reading maximum resistance to zero. Most digital meters will show a high number which flashes (over range) when the circuit is broken (no continuity).
If you get the appropriate response from your meter, hold the two probes onto the light bulb contacts. If the needle of the analog meter moves across the scale or if the digital meter reads zero or a low number then there is continuity and the light bulb is OK.