Checks Before Commencing Troubleshooting - Brother DCP-7090 Service Manual

1.2 Checks before Commencing Troubleshooting

Check the following items before attempting to repair the machine.
 Operating environment
(1) The machine is placed on a flat, stable surface.
(2) The machine is used in a clean environment where the temperature is between 10°C
(50°F) and 32°C (89.6°F) and the relative humidity is maintained between 20% and 80%.
(3) Ensure the machine is not exposed to direct sunlight, excessive heat, moisture, or dust.
(4) Keep the machine horizontal when you carry it. To prevent injuries when moving or lifting
this machine, make sure to use at least two people.
 Power supply
(1) The AC input power supply described on the rating plate of the machine should be within
±10% of the rated voltage.
(2) The AC input power supply is within the regulated value.
(3) The cables and harnesses are connected correctly.
(4) The fuses are not blown.
 Paper
(1) A recommended type of paper is being used.
(2) The paper is not damp.
(3) The paper is not short-grained paper or acid paper.
 Consumable parts
(1) The drum unit (including the toner cartridge and toner box) is installed correctly.
 Others
(1) Condensation
When the machine is moved from a cold place into a warm room, condensation may occur
inside the machine, causing various problems as listed below.
• Condensation on the surface of optical devices such as the lens, reflecting mirror, and
protection glass, etc., may cause light print image.
• If the exposure drum is cold, the electrical resistance of the photosensitive layer is
increased, making it impossible to obtain the correct contrast when printing.
• Condensation on the charge unit may cause corona charge leakage.
• Condensation on the plate and separation pad may cause paper feed problems.
If condensation has occurred, leave the machine for at least two hours to allow it to reach
room temperature.
If the drum unit is unpacked soon after it is moved to a warm room from a cold location,
condensation may occur inside the unit which may cause printing failure. Leave the
drum unit for one or two hours until it reaches room temperature, and then unpack it.
(2) Low temperature
The motor may not drive normally under the low temperature environment. This is due to
there being too much load to drive each unit. In this case, increase the room temperature.
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