Sylvania - EWC1304 - SMPS circuit diagram - Troubleshooting - Mechanical Troubleshooting
Emerson
– Symphonic – Sylvania - EWC1304 EWC1304
- SC313E - 6313CE 13" COLOR TV/VCR COMBINATION
Power
Supply Schematic and Trouble Shooting Guide
It is highly recommended that a variable isolation transformer which can monitor current be used. (Alternatively a variable AC source which monitors current will do). Read directions below before power is added.
It is highly recommended that a variable isolation transformer which can monitor current be used. (Alternatively a variable AC source which monitors current will do). Read directions below before power is added.
SMPS Schematic
Fixed voltage ( or Auto
voltage selectable ) power supply circuit is used in this unit. If Main
Fuse (F601) is blown, check to see that all components in the power
supply circuit are not defective before you connect the AC plug to the
AC power supply. Otherwise it may cause some components in the power
supply circuit to fail.
FOR CONTINUED PROTECTION AGAINST RISK OF FIRE, REPLACE ONLY WITH SAME TYPE 4A, 125V FUSE.
Repair
proceeding
Repair method 1
(Power must be off)
Short circuit in the
secondary side. check diode D613, D614, D616, D617 and D618, switching
transistor (Q601), control transistor (Q602), diode and resistor replace
as necessary. Disconnect 105V diode (D613), 25V diode (D614), 8V diode
(D616), 12V diode (D617), 12V diode (D618) and Check the load
continuity of 105V line, 25V line, 8V line, 12V line through a tester
(resistance range). If the tester indicates a lower resistance value
around 0 ohm, the line is short-circuited. Before repairing the
switching power supply, find out the short-circuited area of such line
and repair it. If the tester does not indicate any low resistance value
(around 0 ohm), no load is short-circuited and there is no problem.
Check for any defective parts while the secondary rectifying diodes are
disconnected (D613, D614, D616, D617 and D618) perform a diode check in
both forward and reverse directions through a tester.
Repair method 2
Check the primary
rectifying diodes (D603-D606) as possible problems. Remove the above
mentioned parts and check them. Perform check according to the step 1
and 2 of repair method #1 and check for defects following
parts, then if necessary replace with factory originals. R602 is open
or not. Q601, Q602, D607, D608 and D611 are short or not.
Repair method 3
The feedback circuit which
is monitored by the output of D613 105V may not work and this may be
regarded as a possible cause, remove IC601 (Photo Coupler), diode (D620)
and transistor (Q604) check for defects.
Repair method 4
Check control circuitly which is connecting to Pin 2 and 1 of Switching Transformer T601.
MECHANICAL TROUBLE INDICATOR
Each
Malfunction Indication
If the MONITOR is turned ON right after the Mechanical Malfunction occurs or POWER SAFETY is turned ON, display the following character to show Malfunction after the EJECT display.
If the MONITOR is turned ON right after the Mechanical Malfunction occurs or POWER SAFETY is turned ON, display the following character to show Malfunction after the EJECT display.
Each
Malfunction evaluation method
P-SAFETY 1 protect
If P-SAFETY 1 port becomes continuously 2.5V or more for 120 msec. (4 times 40 msec. interval), the unit shall immediately turn OFF the POWER/MONITOR and switch over to the Mechanical Malfunction mode with POWER OFF. (To return from this mode shall become possible only by POWER Key as in the case of the Mechanical Malfunction).
P-SAFETY 1 protect
If P-SAFETY 1 port becomes continuously 2.5V or more for 120 msec. (4 times 40 msec. interval), the unit shall immediately turn OFF the POWER/MONITOR and switch over to the Mechanical Malfunction mode with POWER OFF. (To return from this mode shall become possible only by POWER Key as in the case of the Mechanical Malfunction).
POWER
SAFETY
1) POWER SAFETY 2
If P-SAFETY 2 port becomes continuously 2.5V or less for 120 msec. (4 times 40 msec. interval) when P-ON-H port is ON, the unit shall be assumed to be the Power Malfunction 2 and immediately turn OFF the POWER/MONITOR and switch over the Mechanical Malfunction mode with POWER OFF.
(Shall not unload)
(To return from this mode shall become possible only by POWER Key as in the case of the Mechanical Malfunction).
* However the POWER SAFETY 2 function shall be disabled during 500 msec. right after the P-ON-H turns ON.
2) POWER SAFETY 3
If P-SAFETY 3 port becomes continuously 2.5V or over for 120 msec. (4 times 40 msec. interval) when MONITOR is ON, P-SAFETY 3 function is available. After that, if P-SAFETY 3 port becomes continuously 2.5V or less for 120 msec. (4 times 40 msec. interval), the unit shall be assumed to be the Power Malfunction 3 and immediately turn OFF the POWER/MONITOR and switch over the Mechanical Malfunction mode with POWER OFF.
(Shall not unload)
(To return from this mode shall become possible only by POWER Key as in the case of the Mechanical Malfunction).
1) POWER SAFETY 2
If P-SAFETY 2 port becomes continuously 2.5V or less for 120 msec. (4 times 40 msec. interval) when P-ON-H port is ON, the unit shall be assumed to be the Power Malfunction 2 and immediately turn OFF the POWER/MONITOR and switch over the Mechanical Malfunction mode with POWER OFF.
(Shall not unload)
(To return from this mode shall become possible only by POWER Key as in the case of the Mechanical Malfunction).
* However the POWER SAFETY 2 function shall be disabled during 500 msec. right after the P-ON-H turns ON.
2) POWER SAFETY 3
If P-SAFETY 3 port becomes continuously 2.5V or over for 120 msec. (4 times 40 msec. interval) when MONITOR is ON, P-SAFETY 3 function is available. After that, if P-SAFETY 3 port becomes continuously 2.5V or less for 120 msec. (4 times 40 msec. interval), the unit shall be assumed to be the Power Malfunction 3 and immediately turn OFF the POWER/MONITOR and switch over the Mechanical Malfunction mode with POWER OFF.
(Shall not unload)
(To return from this mode shall become possible only by POWER Key as in the case of the Mechanical Malfunction).
Mechanical
Malfunction determination
1) REEL Malfunction detection Countermeasure for REEL and CAPSTAN motor rotation malfunction (Except CASSETTE LOADING function)
After the Malfunction detection with REEL/CAPSTAN sensor, the unit shall switch over to STOP
(B) and be REEL Mechanical Malfunction.
a) If the T-REEL pulse is not impressed after a lapse of 5 sec. at SP, 10 sec. at LP, 14 sec. at SLP, or more in the REEL Rotation Mode like PLAY/REC, FS/RS Mode, and the T-REEL or S-REEL pulse is not impress after a lapse of 4 sec. or more in REEL Rotation Mode of FF/REW, it shall be assumed to stop the rotation and switch over to STOP (B) position, then POWER be turned OFF and the unit be
REEL Mechanical Malfunction. (T-REEL and SREEL for the models on S-REEL and only T-REEL for other models)
b) If the C-FG pulse is not impressed for a lapse of 1 sec. or more during the CAPSTAN MOTOR rotation, it shall be MOTOR Rotation Malfunction (REEL Malfunction).
2) DRUM Malfunction detection
Detect the DRUM rotation at the D-FG input terminal. If the variation of D-FG input level is not detected for a lapse of 1 sec. or more when D-CONT is "H", it shall be assumed to be Rotation Malfunction and be DRUM Malfunction. When detect Drum Malfunction, POWER shall be turned OFF after the unit switches over to STOP
(B) Mode.
3) Countermeasure for TAPE LOADING Malfunction
Detect the Malfunction with the LOADING Switch.
a) TAPE LOADING Malfunction
If LD-SW does not go to the established position after a lapse of 7 sec. or more from TAPE LOADING or TAPE UNLOADING start, the LOADING function shall immediately be stopped and POWER be turned OFF, and inform the Timer about the LOADING Mechanical Malfunction.
b) LD-SW Position Malfunction at each mode When the unit operates at each mode, even if the LD-SW position changes from the established one in its mode, it keeps the function according to its mode.
1) REEL Malfunction detection Countermeasure for REEL and CAPSTAN motor rotation malfunction (Except CASSETTE LOADING function)
After the Malfunction detection with REEL/CAPSTAN sensor, the unit shall switch over to STOP
(B) and be REEL Mechanical Malfunction.
a) If the T-REEL pulse is not impressed after a lapse of 5 sec. at SP, 10 sec. at LP, 14 sec. at SLP, or more in the REEL Rotation Mode like PLAY/REC, FS/RS Mode, and the T-REEL or S-REEL pulse is not impress after a lapse of 4 sec. or more in REEL Rotation Mode of FF/REW, it shall be assumed to stop the rotation and switch over to STOP (B) position, then POWER be turned OFF and the unit be
REEL Mechanical Malfunction. (T-REEL and SREEL for the models on S-REEL and only T-REEL for other models)
b) If the C-FG pulse is not impressed for a lapse of 1 sec. or more during the CAPSTAN MOTOR rotation, it shall be MOTOR Rotation Malfunction (REEL Malfunction).
2) DRUM Malfunction detection
Detect the DRUM rotation at the D-FG input terminal. If the variation of D-FG input level is not detected for a lapse of 1 sec. or more when D-CONT is "H", it shall be assumed to be Rotation Malfunction and be DRUM Malfunction. When detect Drum Malfunction, POWER shall be turned OFF after the unit switches over to STOP
(B) Mode.
3) Countermeasure for TAPE LOADING Malfunction
Detect the Malfunction with the LOADING Switch.
a) TAPE LOADING Malfunction
If LD-SW does not go to the established position after a lapse of 7 sec. or more from TAPE LOADING or TAPE UNLOADING start, the LOADING function shall immediately be stopped and POWER be turned OFF, and inform the Timer about the LOADING Mechanical Malfunction.
b) LD-SW Position Malfunction at each mode When the unit operates at each mode, even if the LD-SW position changes from the established one in its mode, it keeps the function according to its mode.
4)
Countermeasure for CASSETTE LOADING Malfunction
a) CASSETTE IN operating Malfunction If LD-SW does not go to SB position after a lapse of 5 sec. or more from the CASSETTE insertion start, the unit starts the CASSETTE OUT operation. After switch over to CASSETTE OUT operation and then a laps of 5 sec. or more from the CASSETTE OUT operation start, if LD-SW does not go to the EJ position or if START Sensor and END Sensor does not turn "ON" at the EJ position, the unit starts again to insert CASSETTE.
(However in S-INH state, the START/END Sensor shall be disabled).
b) CASSETTE OUT operating Malfunction
After a lapse of 5 sec. or more from CASSETTE OUT operation start, if LD-SW does not go to the EJ position or if START Sensor and END Sensor does not turn "ON" at the EJ position, the unit starts to insert CASSETTE. (However in S-INH state, the START/END Sensor shall be disabled)
a) CASSETTE IN operating Malfunction If LD-SW does not go to SB position after a lapse of 5 sec. or more from the CASSETTE insertion start, the unit starts the CASSETTE OUT operation. After switch over to CASSETTE OUT operation and then a laps of 5 sec. or more from the CASSETTE OUT operation start, if LD-SW does not go to the EJ position or if START Sensor and END Sensor does not turn "ON" at the EJ position, the unit starts again to insert CASSETTE.
(However in S-INH state, the START/END Sensor shall be disabled).
b) CASSETTE OUT operating Malfunction
After a lapse of 5 sec. or more from CASSETTE OUT operation start, if LD-SW does not go to the EJ position or if START Sensor and END Sensor does not turn "ON" at the EJ position, the unit starts to insert CASSETTE. (However in S-INH state, the START/END Sensor shall be disabled)
When
the unit switches over to CASSETTE insertion at CASSETTE IN or CASSETTE OUT
Malfunction, if LD-SW does not go to the SB position after a lapse of 5 sec. or
more from CASSETTE insertion start, the function shall immediately be stopped
and POWER be turned OFF, and the unit be CASSETTE LOADING Malfunction.
c) When POWER is turned ON, if the CL position or GC position cannot be detected after 5 sec. LDREV operation and 5 sec. LD-FWD operation, the function shall immediately be stopped and POWER be turned OFF, and the unit be CASSETTE LOADING Malfunction. d) When POWER is turned ON without CASSETTE (EJ position) and LD-SW is monitored all the time, if the CL or GC position is detected continuously for 1 sec. or more, the POWER shall be turned OFF and the unit be CASSETTE LOADING Malfunction.
c) When POWER is turned ON, if the CL position or GC position cannot be detected after 5 sec. LDREV operation and 5 sec. LD-FWD operation, the function shall immediately be stopped and POWER be turned OFF, and the unit be CASSETTE LOADING Malfunction. d) When POWER is turned ON without CASSETTE (EJ position) and LD-SW is monitored all the time, if the CL or GC position is detected continuously for 1 sec. or more, the POWER shall be turned OFF and the unit be CASSETTE LOADING Malfunction.
Countermeasure
for Mechanical
Malfunction
If the unit detects Mechanical Malfunction, turn the POWER OFF. If the unit is Mechanical Malfunction, Key input except POWER key shall be disabled and CASSETTE insertion disabled. When POWER Key is entered, the POWER is turned ON and the unit switches over the EJECT Mode. (Return with POWER ON)
Malfunction
If the unit detects Mechanical Malfunction, turn the POWER OFF. If the unit is Mechanical Malfunction, Key input except POWER key shall be disabled and CASSETTE insertion disabled. When POWER Key is entered, the POWER is turned ON and the unit switches over the EJECT Mode. (Return with POWER ON)
