Ricoh C211 Service Manual page 680

     
SUBJECT: FLUORESCENT LAMP STABILIZER BREAKAGE
SYMPTOM:
The original transport motor does not work, causing a location "A" jam being displayed. When this occurs,
the exposure lamp and the original pressure solenoid do not turn on, either.
CAUSE:
Due to a short in capacitor "C2", either transistor "Q1" or "Q2" on the fluorescent lamp stabilizer fails. This
causes fuse "FU600" on the A/D conversion board to blow.
This symptom may occur when the scanner unit is opened and closed immediately after turning on the
machine's power.
When the main switch is turned on, the "Lamp On" signal is generated to turn on the exposure lamp. (This is
to stabilize the light intensity of the fluorescent lamp before the start of scanning an original.) The lamp turns
off after 1 minute.
While the "Lamp On" signal is generated, 24-volts DC is supplied to the fluorescent lamp stabilizer. In this
condition, if the scanner unit is opened, the voltage is cut by the safety switch. However, the lamp on signal
stays on (until 1 minute lapses).
If the scanner unit is closed before the "Lamp On" signal turns off (1 minute at most), the voltage is suddenly
supplied to the fluorescent lamp stabilizer. Due to excessive load, there is a possibility of capacitor "C2" on
the fluorescent lamp stabilizer shorting out.
NOTE:
The 24-volts DC supplied to the fluorescent lamp stabilizer is not cut by opening any other
units/doors other than the scanner unit.
This problem rarely occurs since the load applied to "C2" fluctuates widely depending on the timing of closing
the scanner unit. Also, it is not usual to open and close the scanner unit within 1 minute immediately after
turning on the main switch.
SOLUTION:
If this problem occurs, replacing fuse FU600 on the A/D conversion board (P/N-11070713) or the whole A/D
conversion board (P/N-C224 8012) only can cause the same damage again. First, you must check the
fluorescent lamp stabilizer (P/N-C2248006), and replace fuse FU600 if necessary.
From the September '97 production, new software is implemented. The new software turns off the "Lamp
On" signal when the scanner unit (and all other units/doors) is open. Then, it turns on again one second after
the scanner unit is closed (and if it is still within the exposure lamp on timing).
The following ROM is used on the main board for this modification:
New Suffix (P/N)
C224 8075-C
Description
ROM IC134 - M27C512-15F1
Check Sum
98D9