Preva Installation/Service Manual, 00-02-1577, Revision E01
84
Produced
1. On the Logic Board, measure voltages at TP1 (+8.1V) and TP9 (+24V). Use
TP8 or TP10 as Common Return. If any of these voltages are not present
after power is applied, next check voltages on the Power Supply Board.
2. On the Power Supply Board, use TP2 as a common test point to check TP1
+24 volts DC and TP3 8.1 volts DC. Then use TP5 as the common return to
check TP4 for the presence of +12 volts DC, as shown in Figure 61. Should
any of these voltages not be present, replace the Power Supply Board. If
these voltages are correct, next check voltages on the Logic Board.
3. On the Logic Board, measure between TP8 or TP10, the Common Return,
and TP2, mA Program. This voltage should be between 1 and 2 volts DC. If
this voltage is not correct, replace the Logic Board.
4. If this voltage is correct, select 1.5 seconds of exposure time, measure
across pin 1 and pin 2 of the Logic Board at the connector J3. During
exposures, this value should be 24 volts AC. Also measure across pin 2 and
pin 3 of J3. This value should be 24 volts AC. If either voltage is missing,
replace the Logic Board.
5. If these voltages are present, measure for the same values at the Tubehead
Assembly at the connector J5 (black) on the blue and gray conductors and
the blue and brown conductors. If the voltages are not present, inspect the
inter-connect cables between the control and Tubehead Assembly.
Connections for this cable begin with controls at J1 of the Power Supply
Board and J3 of the Logic Board. As shown in Figure 59, an internal set of
connections will be accessed below the distal side of the horizontal arm and
at the inside top of the Tubehead Yoke. The final set of connections is
accessed by removing the Pivot Cap located at the attachment point of the
Tubehead to the Yoke.
6. If the voltages are present, replace the Tubehead Assembly.
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