Overheat Protection - Ricoh G104 Service Manual

Corrections for Small Paper Sizes (less than A5/LT)
These corrections prevent excess heating of the fusing unit when paper widths less
than A5/LT are used. In multi-page printing with this size paper, the heating roller's
temperature is not the same in all areas because the smaller size paper is less
than the width of the heating roller. The temperature at the ends of the roller that do
not touch the paper becomes higher than other points on the roller during multi-
page printing. The following corrections decrease this problem:
• Print speed: This is decreased after 15 pages. Then, 30 seconds after this, the
print speed increases back to the standard speed again. You can adjust with SP
1911-001 to 003.
• Fusing temperature: This is decreased in three stages, as shown below.
• Decreased by 5ºC after 50 pages are printed (controlled by SP 1911-004
and 014)
• Decreased by 5ºC again after 50 more pages are printed (controlled by SP
1911-006 and 016)
• Decreased by 5ºC again after 50 more pages are printed (controlled by SP
1911-008 and 018)
There are also temperature reductions for one-sided printing and two-sided printing.
• One sided printing: The temperature is decreased in two steps, as shown below
• After 15 pages, no reduction (controlled by SP 1911-021 and 023)
• After 15 more pages, decreased by 5ºC (controlled by SP 1911-022 and
024)
• Duplex printing: The temperature is decreased in two steps, as shown below
• After 15 pages, no reduction (controlled by SP 1911-025 and 027)
• After 15 more pages, decreased by 10ºC (controlled by SP 1911-026 and
028)

Overheat Protection

• If the heating roller temperature becomes higher than 230°C, the CPU cuts off
the power to the heating lamp and SC543 occurs.
• If 250°C is detected, the thermostat opens, and the heating lamp power is cut off.
SC545 occurs.
NOTE: 1) If the thermistor output is less than 0°C for six seconds, SC541 occurs.
2) If the heating lamp gets full power for 8 seconds after the heating roller
gets to the print ready temperature, SC545 occurs.
SM
CÓPIA NÃO CONTROLADA
6-61
CÓPIA NÃO CONTROLADA
FUSING
G104