Panasonic KX-FT57E Service Manual ▷ View online
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KX-FT57E
TROUBLESHOOTING GUIDE
Check the solder at the
pin 8 of IC10 and Q5.
pin 8 of IC10 and Q5.
Connect the unit to a
loop simulator.
Switch : TX side T-R
: Connect an oscilloscope.
loop simulator.
Switch : TX side T-R
: Connect an oscilloscope.
Start the MODEM test.
Is signal four at
the Tip-Ring output?
the Tip-Ring output?
Connect a PBX and
TEL. line and go off-hook.
TEL. line and go off-hook.
Check the trace
between pins 28, 29 of
IC5 and the Tip-Ring.
between pins 28, 29 of
IC5 and the Tip-Ring.
Is the signal at pin 38
of IC5 dial tone input?
of IC5 dial tone input?
Replace IC5.
Check the trace
between T1 and pin
38 of IC5.
between T1 and pin
38 of IC5.
Is the signal at pins
28, 29 of IC5 output?
28, 29 of IC5 output?
Is the voltage at pin 8
of IC10 24 V?
of IC10 24 V?
Check the solder at
pin 116 of IC1.
pin 116 of IC1.
Replace IC5.
OK
3 The unit can copy, but can not transmit/receive.
YES
YES
YES
YES
NO
NO
NO
NO
(TEST CODE NO. 554)
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KX-FT57E
Dial
Other party's FAX
machine dials
machine dials
Line Connection
Time
Time
(Time until Response)
False ring
Max 35 sec
3 sec
1 sec
Ringing Time
(about 4 sec/ring)
(about 4 sec/ring)
CED Signal
send
send
DIS Signal
send
send
Other party's
FAX machine
detects the
DIS signal.
FAX machine
detects the
DIS signal.
False ring Send Time
& CNG Detect Time
(about 17 sec depending on the
user program mode #30 setting)
& CNG Detect Time
(about 17 sec depending on the
user program mode #30 setting)
75 msec
Station 1
S1
FAX 1
2 Line Type
2 Line Type
FAX 2
S2
Station 2
A sea bottom cable or satellite com-
munication path. (4 Line Type)
munication path. (4 Line Type)
(Echo/Echo Canceler)
The signal from FAX1 reaches FAX2 via stations 1 and 2, but the reflection signal at station 2 also returns via station 1 (echo). As
the distance between station 1 and station 2 is far, the echo returns to FAX 1 at a max. of 600msec after transmission. So, there
is a possibility that this signal is detected as the signal from FAX 2. For a normal call, there is also a possibility that their own
voice echo will make the call difficult to perceive. For this reason, each station (station 1, station 2) attaches echo cancelers (S1,
S2) for international lines or long distance lines. For the echo canceler, the level of the transmission signal from FAX 1 is
compared with the level of the reception signal from FAX 2, and when the transmission signal is larger, S1 is closed, while S2 is
opened when it is smaller. In other words, when there is transmission from FAX 1, S1 is closed and S2 is open so that the echo
does not return to FAX 1.
The signal from FAX1 reaches FAX2 via stations 1 and 2, but the reflection signal at station 2 also returns via station 1 (echo). As
the distance between station 1 and station 2 is far, the echo returns to FAX 1 at a max. of 600msec after transmission. So, there
is a possibility that this signal is detected as the signal from FAX 2. For a normal call, there is also a possibility that their own
voice echo will make the call difficult to perceive. For this reason, each station (station 1, station 2) attaches echo cancelers (S1,
S2) for international lines or long distance lines. For the echo canceler, the level of the transmission signal from FAX 1 is
compared with the level of the reception signal from FAX 2, and when the transmission signal is larger, S1 is closed, while S2 is
opened when it is smaller. In other words, when there is transmission from FAX 1, S1 is closed and S2 is open so that the echo
does not return to FAX 1.
The unit can copy, but can't transmit/receive long distance or international communication.
The following 2 causes can be the reason for this.
Cause 1:
The other party is executing automatic calling and the call has been received by this unit, but the response with a CED or DIS
signal is too long. (In most cases, this unit detects the CNG signal and can respond to either CED or DIS.) (According to the
ITU-T standard, the communication procedure is stopped when there is no response from the other party within 35 sec, so the
other party releases the line.)
The other party is executing automatic calling and the call has been received by this unit, but the response with a CED or DIS
signal is too long. (In most cases, this unit detects the CNG signal and can respond to either CED or DIS.) (According to the
ITU-T standard, the communication procedure is stopped when there is no response from the other party within 35 sec, so the
other party releases the line.)
(Cause and Countermeasure)
As shown in the chart above, the total handshaking time must be reduced, but because of the long distance connection and
linking of several stations, the line connection time can't be reduced. Accordingly, the following countermeasures should be tried.
(A) The ANS/FAX DELAYED RING count should be 1. (user parameter: code No. 06)
(B) As the 35 sec count is started directly after dialing or after the START button has been pressed for models
As shown in the chart above, the total handshaking time must be reduced, but because of the long distance connection and
linking of several stations, the line connection time can't be reduced. Accordingly, the following countermeasures should be tried.
(A) The ANS/FAX DELAYED RING count should be 1. (user parameter: code No. 06)
(B) As the 35 sec count is started directly after dialing or after the START button has been pressed for models
with a START button, the other party should be called manually, if possible.
Another possibility is entering two pauses at the end of the auto dial number on the transmission side. This way, the count
Another possibility is entering two pauses at the end of the auto dial number on the transmission side. This way, the count
start
time can be delayed by 2 pauses (about 10 sec).
Cause 2:
Erroneous detection occurred because of an echo or an echo canceler.
Erroneous detection occurred because of an echo or an echo canceler.
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KX-FT57E
TROUBLESHOOTING GUIDE
(Cause and Countermeasure)
(Cause A)
When the training signal is transmitted from FAX1 during the communication procedure at the time of transmission from FAX1
to FAX2, there is a delay until the echo canceler operates and S1 is closed. Therefore, a part of the head of the training signal
may drop out and normal reception by FAX2 may not be possible, and transmission may not be started.
(Countermeasure A)
When the international line mode becomes ON in the service mode (code No. 521), a dummy signal is attached to the head of
the training signal to prevent this problem. As this normally is ON, it is necessary to reconfirm that this has not become OFF.
When the international mode is switched to OFF, the transmission side will try the training signal three times at each speed
(9600BPS, 4800BPS and 2400BPS). When it is NG, it will drop the speed by one rank (fall-back). When the international mode
is switched to ON, each speed will be tried only twice. In other words, the slower speed with fewer errors is reached more
easily. This is done as line conditions may deteriorate and the picture may be affected more during communication with
international lines or long distance communication, even when the training has been OK. The default value is ON as
preference is given to clearer pictures rather than speed.
(Cause A)
When the training signal is transmitted from FAX1 during the communication procedure at the time of transmission from FAX1
to FAX2, there is a delay until the echo canceler operates and S1 is closed. Therefore, a part of the head of the training signal
may drop out and normal reception by FAX2 may not be possible, and transmission may not be started.
(Countermeasure A)
When the international line mode becomes ON in the service mode (code No. 521), a dummy signal is attached to the head of
the training signal to prevent this problem. As this normally is ON, it is necessary to reconfirm that this has not become OFF.
When the international mode is switched to OFF, the transmission side will try the training signal three times at each speed
(9600BPS, 4800BPS and 2400BPS). When it is NG, it will drop the speed by one rank (fall-back). When the international mode
is switched to ON, each speed will be tried only twice. In other words, the slower speed with fewer errors is reached more
easily. This is done as line conditions may deteriorate and the picture may be affected more during communication with
international lines or long distance communication, even when the training has been OK. The default value is ON as
preference is given to clearer pictures rather than speed.
(Cause B)
The echo canceler operation is stopped by a signal of 2100Hz (i.e. S1 and S2 become ON).
Accordingly, when FAX1 has executed automatic reception, a CED signal is output, and if this signal is 2100Hz, S1 and S2
will become ON. Then the echo of the DIS signal output afterwards may be received and FAX1 may execute an erroneous
operation, preventing communication from starting.
(Countermeasure B)
In the service mode, the CED signal frequency is set to 1100 Hz (code No.520) or the time setting between the CED signal
and the DIS signal is set from 75msec to 500msec (code No.593). This is done because the echo canceler operation stop
mode is cancelled by an interval of 250msec or more.
The echo canceler operation is stopped by a signal of 2100Hz (i.e. S1 and S2 become ON).
Accordingly, when FAX1 has executed automatic reception, a CED signal is output, and if this signal is 2100Hz, S1 and S2
will become ON. Then the echo of the DIS signal output afterwards may be received and FAX1 may execute an erroneous
operation, preventing communication from starting.
(Countermeasure B)
In the service mode, the CED signal frequency is set to 1100 Hz (code No.520) or the time setting between the CED signal
and the DIS signal is set from 75msec to 500msec (code No.593). This is done because the echo canceler operation stop
mode is cancelled by an interval of 250msec or more.
(Cause C)
The KX-FT57E shall be assumed as FAX1 and a different company's set shall be assumed as FAX2.
For transmission from the KX-FT57E to FAX2, FAX2 executes automatic reception and transmits a CED signal (2100 Hz)
followed by a DIS signal. As the echo cancelers here stop as described in cause B, the echo of the DIS signal returns to FAX 2.
On the other hand, the KX-FT57E detects the DIS signal and transmits a DCS signal. In other words, it is possible that the echo
of the DIS signal and the DCS signal transmitted from the KX-FT57E reach FAX 2 one after the other, FAX 2 executes
erroneous detection, and communication is not started.
(Countermeasure C)
When the international DIS detection setting is made effective in the service mode (code No.594), the KX-FT57E does not
respond to the first DIS signal and returns a DCS signal only for the second DIS signal.
In other words, there is a 250msec interval between the transmission of the first and second DIS signal. So, the echo cancelers
operation recovers and no echo is generated for the second DIS signal.
Note:
When the other FAX does not respond with a DCS signal after DIS signal transmission, the DIS signal is transmitted three times.
The KX-FT57E shall be assumed as FAX1 and a different company's set shall be assumed as FAX2.
For transmission from the KX-FT57E to FAX2, FAX2 executes automatic reception and transmits a CED signal (2100 Hz)
followed by a DIS signal. As the echo cancelers here stop as described in cause B, the echo of the DIS signal returns to FAX 2.
On the other hand, the KX-FT57E detects the DIS signal and transmits a DCS signal. In other words, it is possible that the echo
of the DIS signal and the DCS signal transmitted from the KX-FT57E reach FAX 2 one after the other, FAX 2 executes
erroneous detection, and communication is not started.
(Countermeasure C)
When the international DIS detection setting is made effective in the service mode (code No.594), the KX-FT57E does not
respond to the first DIS signal and returns a DCS signal only for the second DIS signal.
In other words, there is a 250msec interval between the transmission of the first and second DIS signal. So, the echo cancelers
operation recovers and no echo is generated for the second DIS signal.
Note:
When the other FAX does not respond with a DCS signal after DIS signal transmission, the DIS signal is transmitted three times.
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KX-FT57E
SYMPTOM
COUNTERMEASURE
1. The TAD/FAX RING count should be 1.
(user parameter: code No. 06)
2. If possible, manual transmission should be made from
the transmission side.
3. If possible, two pauses should be inserted at the end of
the auto dial number on the transmission side.
4. If possible, the Function Selector Switch should be
switched to FAX.
Does not receive in automatic mode.
Does not transmit.
1. Confirm that the international line mode is ON.
(service mode: code No. 521)
2. The international DIS detection setting should be made
effective. (service mode: code No. 594)
Does not receive.
1. Set the time setting between the CED signal and the DIS
signal to 500msec. (service mode: code No. 593)
2. Set the CED frequency to 1100Hz.
(service mode: code No. 520)
Unit can copy, but the transmission and reception image is incorrect.
(Long distance or international communication operation)
(Long distance or international communication operation)
This depends widely on the transmission and reception capability of the other FAX unit and the line conditions.
The countermeasures for this unit are shown below.
The countermeasures for this unit are shown below.
Transmission Operation:
Set the transmitting speed to 4800BPS (service mode: code No. 717) or select the overseas mode. (Individual
correspondence according to the other unit is recommended.)
Set the transmitting speed to 4800BPS (service mode: code No. 717) or select the overseas mode. (Individual
correspondence according to the other unit is recommended.)
Reception Operation:
If 80% or more of the reception is incorrect, set the receiving speed to 4800BPS. (service mode: code No. 718)
If 80% or more of the reception is incorrect, set the receiving speed to 4800BPS. (service mode: code No. 718)
Summary:
Long distance and international communication operations
Long distance and international communication operations
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