Specifications

24 Revision 4 – 1-7-2008 FTB 312-4
Power Converter
Burst Choke (L1)
Measure the resistance of L1 from TB3-5
to ceramic post E4 (at burst resistor R2).
Its resistance should be approximately 7
ohms.
Relays (K2, K3)
A malfunctioning relay may have faulty
contacts, a sticky mechanism, or a
defective coil. You may determine the first
two possibilities by inspection and
manually exercising the armature. You can
confirm a defective coil by measuring the
resistance. To measure the resistance of
relay coils, first remove the wires from
one of the connections to the coil terminals
on the relay.
The resistance across the coil of the K2
Mode Relay or the K3 Discharge Relay
should measure approximately 290 ohms.
Timing and Trigger Board (PCB1)
Replace this circuit board with one known
to be in good condition.
HV Rectifier Board (PCB2)
Replace this circuit board with one known
to be in good condition.
Sense Board (PCB4)
Replace this circuit board with one known
to be in good condition.
Discharge Resistor (R1)
The resistance of R1 between ceramic
posts E1 and E2 should be 35,000 ohms.
Burst Resistor (R2)
The resistance of R2 between posts E3 and
E4 should be 500 ohms.
Power Transformer (T1)
To test this transformer, first remove the
PCB1 and the HV rectifier board (PCB2).
Apply power to the unit and measure
secondary winding voltages at the
terminals indicated below:
Terminals
Voltage Range
Allowed
TB3-1 to TB3-9 900-1050 VAC
Terminal 2 of
Relay K2 or K3 to
chassis
100-120 VAC
J3-1 to J3-2 on
PCB1
22-26 VAC
If the voltage on TB3-1 to TB3-9 is
substantially below the specified minimum
value, check the C4 Tuning Capacitor.
Flashhead
Flashtube (FT101)
Visually inspect the flashtube for broken
electrodes, cracked glass, and the solder
connections of the pins. A darkened
envelope does not necessarily mean the
light output would be unacceptable.
Before concluding that a faulty flashtube
is responsible for an inadequate flash, first
rule out other possible causes such as
weak or absent discharge voltage or
triggering pulses.
Trigger Transformer (T101)
The measured resistance of the secondary
winding (potted assembly) should be
approximately 150 ohms. Check the ferrite
core for cracks. Check the mounting
screws for tightness.