I have before you, the ballast circuit board from a fluorescent light fixture (27w FML bulb).
Specs on outside of ballast say: 120v .38A 60hz 27w
(How is that accurate when P=IV 45.6W = 120v * .38A) ?
I have tested wire continuity from plug to switch to ballast input on both hot and neutral wires. I have checked continuity of all four
output wires from ballast to bulb socket. It all checks out. I believe the starter exists in the base of the bulb so none exists in the fixture.
The only reason remaining is that my ballast is bad. Now normally I'd buy a new ballast but not only is this one impossible to find but more importantly its an exercise in learning for me that I don't want to pass up.
At some point I'd like to take this circuit and master it. In other words its AC and I haven't gotten to that point yet. I'm not sure if the output is supposed to be ac or its being converted to DC - how can I tell? Someday I want to be able to trace the circuit path and draw it out in software and understand exactly whats going on electrically. For right now I just want to identify which part (or parts) are faulty, desolder them, and solder in replacements. Can you guys help me on this?
I will have many questions as I go along on this project and am genuinely grateful for your help.
Notes
------
1. Behind each of the 13003's there is a diode that you can't see in the photograph! They test VERY low using diode test mode of meter, .007 volts (James Bond diodes?)
2. I have 7-8v when I test the potential of one yellow wire to one red wire on the output side and ditto for the 2nd red/yellow pair. Seems way too low.
3. I don't have any obviously cooked parts (burst capacitor, melted resistor etc) so its going to be all up to me and the meter though I do see some yellow discoloration on part of the trace beneath one of the 13003's.
Questions
----------
1. Do I have to desolder ANY device in order to test it (even 1)? It has resistors, capacitors, diodes, dual 13003 (mosfet?), transformer and a few parts I can't identify yet because I'm noob lol.
2. What is the green thing next to the transformer? Looks like a green donut with 3 wires wrapped around it coming into 6 contact points to the board?
3. What path/process of elimination would you take in trying to find the faulty component? I suspect the 13003's due to yellowing of the traces beneath one (very yellow) and slightly yellow on the other. Except I have no idea how to test them. I looked up a data sheet and found this:
http://pdf1.alldatasheet.com/datasheet-pdf/view/391739/PFS/13003.html
Notice it doesn't say "Hey this is a MOSFET or qfet or baked potato" nor does it say NPN or PNP but I assume (ugh) its NPN. This gives me a side question. Is NPN tied to Emitter Base Collector/ Source Gate Drain? In other words if we rearrange the pins, the name NPN remains even tho the physical layout of the pins can be NNP or PNN etc?
Sorry for the long post but I really do want to be able to identify and repair this thing even tho its presently beyond my abilities so for now I'll be more than satisfied to test each and every part (since so few of them on the board - only 32 components in all) to identify the bad ones to replace.
[note in photo the trace photo is upside down as I had to flip it over for photo]
Specs on outside of ballast say: 120v .38A 60hz 27w
(How is that accurate when P=IV 45.6W = 120v * .38A) ?
I have tested wire continuity from plug to switch to ballast input on both hot and neutral wires. I have checked continuity of all four
output wires from ballast to bulb socket. It all checks out. I believe the starter exists in the base of the bulb so none exists in the fixture.
The only reason remaining is that my ballast is bad. Now normally I'd buy a new ballast but not only is this one impossible to find but more importantly its an exercise in learning for me that I don't want to pass up.
At some point I'd like to take this circuit and master it. In other words its AC and I haven't gotten to that point yet. I'm not sure if the output is supposed to be ac or its being converted to DC - how can I tell? Someday I want to be able to trace the circuit path and draw it out in software and understand exactly whats going on electrically. For right now I just want to identify which part (or parts) are faulty, desolder them, and solder in replacements. Can you guys help me on this?
I will have many questions as I go along on this project and am genuinely grateful for your help.
Notes
------
1. Behind each of the 13003's there is a diode that you can't see in the photograph! They test VERY low using diode test mode of meter, .007 volts (James Bond diodes?)
2. I have 7-8v when I test the potential of one yellow wire to one red wire on the output side and ditto for the 2nd red/yellow pair. Seems way too low.
3. I don't have any obviously cooked parts (burst capacitor, melted resistor etc) so its going to be all up to me and the meter though I do see some yellow discoloration on part of the trace beneath one of the 13003's.
Questions
----------
1. Do I have to desolder ANY device in order to test it (even 1)? It has resistors, capacitors, diodes, dual 13003 (mosfet?), transformer and a few parts I can't identify yet because I'm noob lol.
2. What is the green thing next to the transformer? Looks like a green donut with 3 wires wrapped around it coming into 6 contact points to the board?
3. What path/process of elimination would you take in trying to find the faulty component? I suspect the 13003's due to yellowing of the traces beneath one (very yellow) and slightly yellow on the other. Except I have no idea how to test them. I looked up a data sheet and found this:
http://pdf1.alldatasheet.com/datasheet-pdf/view/391739/PFS/13003.html
Notice it doesn't say "Hey this is a MOSFET or qfet or baked potato" nor does it say NPN or PNP but I assume (ugh) its NPN. This gives me a side question. Is NPN tied to Emitter Base Collector/ Source Gate Drain? In other words if we rearrange the pins, the name NPN remains even tho the physical layout of the pins can be NNP or PNN etc?
Sorry for the long post but I really do want to be able to identify and repair this thing even tho its presently beyond my abilities so for now I'll be more than satisfied to test each and every part (since so few of them on the board - only 32 components in all) to identify the bad ones to replace.
[note in photo the trace photo is upside down as I had to flip it over for photo]
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