Ricoh FT7770 Service Manual page 87

- Toner Supply -
When the CPU energizes the toner supply clutch, the toner supply roller
feeds toner to the developer tank for a set period of each copy cycle. This
continues until the low toner density condition is recovered.
This copier has two different ways of controlling the amount of toner sup-
plied. Normally, the detect supply system is used to control toner supply.
However, if the ID sensor output becomes abnormal, the CPU automatically
selects the fixed supply mode, and enough toner for a 7% black area copy is
added on each copy cycle.
The period of toner supply is automatically determined by the CPU based on
the setting of SP 10-3 and 10-4 (as shown in the table on the next page)
and on the copy paper size.
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April, '89