Panasonic SJ-MR220 Service Manual page 35

Part No.
Circuit
No.
IC304 C0DBAGZ00006 DC-DC converter
IC901 C0GBE000003 Optical head lift
IC601 C0FBAJ000008 A/D
9. Display of Self-Diagnostic Function
This model is equipped with a self-diagnosis function and shows, when necessary, the following
indication in the LCD section of the set.
Function
Recording is
/ 3.5V / Power impracticable.
IC for magnetic
head driver
control
Recording is
motor drive impracticable.
Magnetic head
fails to descend.
Optical input
CONVERTER permits recording,
but line input does
not.
MIC recording is
impracticable.
Symptom Check point
Confirm the
voltage of IC902
(pin 14) or (TP137)
Confirm the
voltage of IC501
(pin 74)
Confirm the
motor drive wave
form of TP145,146,
147 and 148 (CN901
pins 1,2,3 and 4).
Make sure of
IC101 (pin 27) input
wave form (during
MIC/LINE input
time).
35
Result and measure
If voltage at TP137
normal and voltage
IC501 is unusual, check
IC501 and switch
periphery.
If voltage at TP137
unusual, replace IC304.
If drive wave form
normal, check FPC
condition of solder
around lift motor, and
nothing unusual is
found, replace the
motor.
If drive wave form
unusual, check supply
voltage of IC401 and
peripheral solder, and
nothing unusual is
found, replace IC401.
If input wave form
IC601 is unusual, check
supply voltage of IC701
and peripheral solder,
and if nothing unusual
found, replace IC701.
If input wave form
IC601 is normal, check
IC601 and perihperal
circuit.