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28-551: PROCESSOR DRUM HEATER Failure
Processor failed to warm up when heater turned on.
Summary
The HEATER has been turned on, but the expected temperature rise did not occur. (Refer to sheet 2 of the SYSTEM Functional Block/Wiring Diagram.) When power is applied to the IMAGER, the PROCESSOR DRUM turns on, controlled by the SSR DRUM PROC signal from the MCS Board. This pulse-width modulated signal remains low (active) until the PROCESSOR DRUM RTD indicates that the DRUM is at operating temperature. (See 28-506 for a description of RTD functions.) The normal warmup process takes from 18-20 minutes. The HEATERS warm up at a rate of about 1.5 degrees C every 30 seconds when power is continuously applied. As long as the SSR DRUM PROC signal is low, the K1 SOLID STATE RELAY on the PROCESSOR INTERFACE BOARD (PIB) routes 120 vac to the DRUM HEATER. (Note that the DRUM HEATER element circuit includes a resettable THERMAL BREAKER.)
The 120 vac is applied through RELAY K2 on the PIB. The ac power should be present at the J1 CONNECTOR of the PIB as long as the TOP HOOD INTERLOCK is closed (HOOD down).
Result of Error
The IMAGER is unable to print film. It can accept and queue new jobs, but it will not initiate new films. All films in the IMAGER will be reprinted. The error can be cleared by only by restarting the IMAGER.
User Action
1. Restart the IMAGER.
2. If the error persists, call Service.
FE Action
1. Is the DRUM warm at all? If not, turn off IMAGER power, open the TOP HOOD, and check for a short in the DRUM HEATER circuit as follows:
a. Remove 3 SCREWS from the END CAP of the HEATER. (Or remove 2 SCREWS and pivot the END CAP out of the way.)
b. Check the THERMAL BREAKER BUTTON inside the DRUM. If it has popped out, use a SCREWDRIVER to pop it back in.
c. Apply power and check to see if the BREAKER BUTTON pops back out. If it does, there is probably a short in the HEATER wiring, and the DRUM should be replaced. Otherwise, proceed as follows.
2. Power off and check resistance of the HEATER ELEMENT (through the SLIP RINGS). Resistance should be about 30 ohms. If the HEATER ELEMENT is open, replace the DRUM.
3. Check that the RTD CABLE is plugged into the MCS BOARD (J17 on the upper right corner of the BOARD). Also check that calibration JUMPER PLUG JP7 is plugged into the NORM position on the BOARD.
4. Check for other possible problems in the following order:
? Loss of 120 vac. (Check at CONNECTOR J1 of the PIB. Pins 1 and 4 are “Line.” Pins 3 and 6 are “Neutral.”)
? Low ac voltage (i.e., 120 vac supply is below spec).
? Defective TOP HOOD INTERLOCK
? Worn SLIP RINGS
? Defective RELAY K1 or K2 on the PIB. (Replace the BOARD.)
? Bad MCS BOARD (monitors DRUM temperature and turns on HEATER as required)
? If the room temperature is set back during non--working hours, try bringing the room temperature up early so the IMAGER has more time to recover. | 
