Samsung RF20HFENB Service Manual page 51

TROUBLESHOOTING
4-2-5. If Power is not supplied
Caution
At the power of main PCB, AC input power
and a high voltage over DC170V(325V)are
occurred. Please take care of yourself on
repair and measurement.
Common PCB Ground
REG1 Heater Sink
Check in SMPS part
☞ Checking method of voltage SMPS input ;
VAR1 both terminals, or CN10 both terminal
AC power.
☞ Checking method of DC secondary output voltage
REG1 input ; Regulator 7805 input → Same
wih C111 both terminals.
DC 12.0V ± 0.8V
☞ Checking method of DC secondary output voltage
REG1 input ; Regulator 7805 input → Same
with C113 both terminals.
DC 5V ± 0.5V
- Check Main PCB connection
- Check the connections between
upper hinge Cabi-Door
- Check Door Panel PCB connection
Is plug connected in ?
Input Voltage
115V ± 15%
Is Fuse
on the SMPS PCB
normal?
Is 115V
applied to both terminals of
SMPS power VAR1 ?
Is DC 170V
applied to both terminals of
BD101 +,-?
Is 12V applied to
both terminal of C111?
Is 5V
applied to both terminal of
C113?
Does
Panel PCB operates
normally?
Is the load
such as relay
normal?
Is there any
PCB soldering, Short, or
breakage?
Normal (Recheck)
51
- Refer to function and 'reference'
parts in the manual when
checking Main PCB
Connect plug again, & check the plug
loosening.
1) Change FUSE AC 250V 2.0A
2) Replace PCB ASS'Y
Check the assembly and connection of
wire
1) Check PCB PATTERN and replace
BD1
2) Replace PCB ASS'Y
Replace PCB ASS'Y
1) Check REG1 (KA7805)
2) Replace PCB ASS'Y
1) Check & repair the assembly of wire
2) Replace Panel PCB
1) Check the contact of Lead Wire
2) Replace the applicable Relay
(Replace PCB Main)
1) Solder again
2) Replace PCB Main