Power Supply Circuit; Primary Circuit - Casio A-10 Operation, Service Manual & Parts List

POWER SUPPLY CIRCUIT

The power supply circuit consists of 4 blocks which are Primary circuit, 5 V circuit, 3 V circuit and 25 V
circuit as follows;
Alkaline
NiMH

Primary Circuit

The voltage from both batteries, alkaline and NiMH, supplies to V5 and V3 circuits through the fuse when
the battery is loaded.
The VBAT2 and RBATCHG are for the reference voltage for Primary detectors. VBAT2 is for alkaline
batteries detector. RBATCHG is for NiMH detector.
RBATMAIN is for AC adaptor detector. It detects whether AC adaptor is used or not.
VDETDRB is to prevent overdischarge of NiMH. When the unit turns off automatically caused by low bat-
tery of NiMH, VDETDRB from detector is H. Then Q54 turns off, it makes the GND line for NiMH cut.
Alkaline NiMH
(1.6 ~ 3.4 V) (1.9 ~ 2.8 V)
Charger
AC Adaptor
Fuse
Primary
circuit
To Detector (RBATMAIN)
AC Adaptor
To Primary Detector (VBAT2)
To Primary Detector (RBATCHG)
Q54
5 V circuit
3 V circuit
Lithium
VBAT2 (to Detector)
Fuse
FS1
Q53
D15
VDETDRB (Normally H)
RBATCHG (to Detector)
RBATMAIN (to Detector)
— 34 —
To Secondary Detector (V5MAIN)
5 V system
To Secondary Detector (V3MAIN)
3 V system
25 V system
25 V circuit
To Detector (VSUB)
To V3 and V5 circuits.