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Flashlamps
1. I have a flash1amp that never lights.
Check the bulb . Check the TIPI02 transistor that drives the flashlamp, Be sure the wires that go to
the flash lamp socket are not broken. The 2N4403 can alsocause this problem .
2. I have a tlashlamp that is always On or, On very bright.
Check the TIPI02 and 2N4403 transistors that drive the flashlamp . The 74LS374 latch sometimes
causes a flashlamp to stay On.
3. None of the flashlamps turn On.
Check for +20Vat the bulb socket . Check
FIll
and BR4.
FIll
is probably blown.
4. One or two tlashlamps seem to bum out more often then the rest.
There is probably more then +20Vgetting into that flashlamps circu it. Check the voltage from the
flashlamp to ground. If there is more then +20V one of the wires going to that bulb is coming in
contact with another voltage sou rce . If the voltage is correct then the TIPI02 is probably.
General Dlumination
1.A single General Dlumination string of bulbs doesn't turn On.
Check the fuse that controls that string . Ifthe fuse is good,check to see if there is voltage at the bulb
sockets. If there is no voltage the wire going from the fuse to the bulbs is open. If there is check the
tr iac that drives the G.!. string.
2. None of the General Illumination bulbs turn On.
Check the 74LS374 latch . Check for 6.3V AC coming to the Power Driver Board from the
transformer .
3. A single General Illumination string doesn't dim,
Most likely, the triac that controls that string is defective. The 74LS374 latch might cause such a
problem.
4. None of the General Dlumination strings dim.
Most likely, the 74LS374 latch or the zero cross circuit is defective. If the zero cross circuit is
defective its probably the LM339 comparator. In rare cases the microprocessor would cause such a
problem.
5. The General Illumination strings don't turn Off.
The zero cross circuit is the problem . Most like ly,the LM339 comparator is defective. In rare cases
the microprocessor can cause a problem like this .
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