TOSHIBA CF30C50 TV

[Daryle Brooks]

Greetings. I have a ten year old Toshiba 30 inch color tv. Model is
CF30c50.It has been a reliable tv until now. The screen started,for
lack of a better term,pull in on the right and have a wiggling pattern
to it. It turned itself off after that. Being a ham operator with some
electronics repair/building experience,I decided to take a look at
the innards of this. I found that,after discharging the crt,that the
HOT had shorted,and the fuseable resistor,r441,had gotten hot enough
to melt the solder joints,both on it's connection to the board,and
those of the wire harness next to it,which lead off the board(power
supply section) to the deflection yoke.A curious note about the r441
fuseable resistor was that it hadn't blown open. Another note that it
also was obvious that this particular resistor was soldered to the
board with long leads so it was raised above the board for cooling,no
heat sink of course.I repaired the board and replaced the
HOT(2SD1556/crossed to an NTE 2331),checked
the service manual voltages.Ok waveforms.Then put the thing back into
normal mode. No sound or video,only snow on the crt.After a half an
hour,it automatically shuts off. I am thinking maybe the crt has a
short,and the xray protection circuit is doing it's work??? I used to
repair my own tv's awhile back,but this is new to me. I can source a
new power supply board for 150.00 but don't know if this is worth
fixing. Any suggestions?

Daryle
WB7TNE

 

[Jerry G.]

This would be complex over an email. These sets are complicated to work on.
Most likely the new transistor is damaged. The flyback may also be
defective, and also some support components. It is very possible that the
power supply may also have to be serviced as well, since there was a short
in the horizontal output section.

If you like the set, take it to a service place that services Toshiba sets.
They are used to this type of work and most likely have the service manuals
to work with. These sets can be a challenge even for an experienced tech.

--

Greetings,

Jerry Greenberg GLG Technologies GLG
=========================================
WebPage http://www.zoom-one.com
Electronics http://www.zoom-one.com/electron.htm
=========================================


"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402111514.76e31d30@posting.google.com...
Greetings. I have a ten year old Toshiba 30 inch color tv. Model is
CF30c50.It has been a reliable tv until now. The screen started,for
lack of a better term,pull in on the right and have a wiggling pattern
to it. It turned itself off after that. Being a ham operator with some
electronics repair/building experience,I decided to take a look at
the innards of this. I found that,after discharging the crt,that the
HOT had shorted,and the fuseable resistor,r441,had gotten hot enough
to melt the solder joints,both on it's connection to the board,and
those of the wire harness next to it,which lead off the board(power
supply section) to the deflection yoke.A curious note about the r441
fuseable resistor was that it hadn't blown open. Another note that it
also was obvious that this particular resistor was soldered to the
board with long leads so it was raised above the board for cooling,no
heat sink of course.I repaired the board and replaced the
HOT(2SD1556/crossed to an NTE 2331),checked
the service manual voltages.Ok waveforms.Then put the thing back into
normal mode. No sound or video,only snow on the crt.After a half an
hour,it automatically shuts off. I am thinking maybe the crt has a
short,and the xray protection circuit is doing it's work??? I used to
repair my own tv's awhile back,but this is new to me. I can source a
new power supply board for 150.00 but don't know if this is worth
fixing. Any suggestions?

Daryle
WB7TNE

 

[James Sweet]

"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402111514.76e31d30@posting.google.com...

Greetings. I have a ten year old Toshiba 30 inch color tv. Model is
CF30c50.It has been a reliable tv until now. The screen started,for
lack of a better term,pull in on the right and have a wiggling pattern
to it. It turned itself off after that. Being a ham operator with some
electronics repair/building experience,I decided to take a look at
the innards of this. I found that,after discharging the crt,that the
HOT had shorted,and the fuseable resistor,r441,had gotten hot enough
to melt the solder joints,both on it's connection to the board,and
those of the wire harness next to it,which lead off the board(power
supply section) to the deflection yoke.A curious note about the r441
fuseable resistor was that it hadn't blown open. Another note that it
also was obvious that this particular resistor was soldered to the
board with long leads so it was raised above the board for cooling,no
heat sink of course.I repaired the board and replaced the
HOT(2SD1556/crossed to an NTE 2331),checked
the service manual voltages.Ok waveforms.Then put the thing back into
normal mode. No sound or video,only snow on the crt.After a half an
hour,it automatically shuts off. I am thinking maybe the crt has a
short,and the xray protection circuit is doing it's work??? I used to
repair my own tv's awhile back,but this is new to me. I can source a
new power supply board for 150.00 but don't know if this is worth
fixing. Any suggestions?

Daryle
WB7TNE

The tube is probably just fine, but obviously there's another problem with
the set, I'd look at the power supply or take it in to a shop if the pic was
good before.

 

[Ampdoc]

The unit is supposed to shut down with a no-signal condition. Check to see
why the tuner isn't working, look at the scan-derived power sources that run
the tuner, just off the flyback you should find some diodes and fusible
resistors, check those.


--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402111514.76e31d30@posting.google.com...

Greetings. I have a ten year old Toshiba 30 inch color tv. Model is
CF30c50.It has been a reliable tv until now. The screen started,for
lack of a better term,pull in on the right and have a wiggling pattern
to it. It turned itself off after that. Being a ham operator with some
electronics repair/building experience,I decided to take a look at
the innards of this. I found that,after discharging the crt,that the
HOT had shorted,and the fuseable resistor,r441,had gotten hot enough
to melt the solder joints,both on it's connection to the board,and
those of the wire harness next to it,which lead off the board(power
supply section) to the deflection yoke.A curious note about the r441
fuseable resistor was that it hadn't blown open. Another note that it
also was obvious that this particular resistor was soldered to the
board with long leads so it was raised above the board for cooling,no
heat sink of course.I repaired the board and replaced the
HOT(2SD1556/crossed to an NTE 2331),checked
the service manual voltages.Ok waveforms.Then put the thing back into
normal mode. No sound or video,only snow on the crt.After a half an
hour,it automatically shuts off. I am thinking maybe the crt has a
short,and the xray protection circuit is doing it's work??? I used to
repair my own tv's awhile back,but this is new to me. I can source a
new power supply board for 150.00 but don't know if this is worth
fixing. Any suggestions?

Daryle
WB7TNE

 

[Daryle Brooks]

Well,Jammy. I checked your suggestions. Was looking past the problem.
Found a 5v regulator that supplies both the tuner and audio with the
output tab disconnected from the board. Odd that it would fold up out
of the board. Heating? Tv is working ok other than it still has right
side pull in on screen when first turned on.Tap the case and the
screen goes normal. Doesn't show this symptom after 15 minutes of
warmup and operation? The pull in symptom looks like inward bowing??
Thanks for the suggestions? HV shows 30.6 with probe.
Daryle
WB7TNE

"Ampdoc" <ampdoc@NOSPAMhotmail.com> wrote in message news:<ScCWb.47546$uS3.28668@bignews4.bellsouth.net>...

The unit is supposed to shut down with a no-signal condition. Check to see
why the tuner isn't working, look at the scan-derived power sources that run
the tuner, just off the flyback you should find some diodes and fusible
resistors, check those.


--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402111514.76e31d30@posting.google.com...
Greetings. I have a ten year old Toshiba 30 inch color tv. Model is
CF30c50.It has been a reliable tv until now. The screen started,for
lack of a better term,pull in on the right and have a wiggling pattern
to it. It turned itself off after that. Being a ham operator with some
electronics repair/building experience,I decided to take a look at
the innards of this. I found that,after discharging the crt,that the
HOT had shorted,and the fuseable resistor,r441,had gotten hot enough
to melt the solder joints,both on it's connection to the board,and
those of the wire harness next to it,which lead off the board(power
supply section) to the deflection yoke.A curious note about the r441
fuseable resistor was that it hadn't blown open. Another note that it
also was obvious that this particular resistor was soldered to the
board with long leads so it was raised above the board for cooling,no
heat sink of course.I repaired the board and replaced the
HOT(2SD1556/crossed to an NTE 2331),checked
the service manual voltages.Ok waveforms.Then put the thing back into
normal mode. No sound or video,only snow on the crt.After a half an
hour,it automatically shuts off. I am thinking maybe the crt has a
short,and the xray protection circuit is doing it's work??? I used to
repair my own tv's awhile back,but this is new to me. I can source a
new power supply board for 150.00 but don't know if this is worth
fixing. Any suggestions?

Daryle
WB7TNE

 

[Ampdoc]

Your deflection problem is a bad solder joint. Look the PCB over real well
in good light with a magnifier, look especially around components that get
hot normally or have large pins. Look real well in the Horizontal section
and you'll probably find it.


--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402191224.52d852a0@posting.google.com...

Well,Jammy. I checked your suggestions. Was looking past the problem.
Found a 5v regulator that supplies both the tuner and audio with the
output tab disconnected from the board. Odd that it would fold up out
of the board. Heating? Tv is working ok other than it still has right
side pull in on screen when first turned on.Tap the case and the
screen goes normal. Doesn't show this symptom after 15 minutes of
warmup and operation? The pull in symptom looks like inward bowing??
Thanks for the suggestions? HV shows 30.6 with probe.
Daryle
WB7TNE

"Ampdoc" <ampdoc@NOSPAMhotmail.com> wrote in message
news:<ScCWb.47546$uS3.28668@bignews4.bellsouth.net>...
The unit is supposed to shut down with a no-signal condition. Check to
see
why the tuner isn't working, look at the scan-derived power sources that
run
the tuner, just off the flyback you should find some diodes and fusible
resistors, check those.


--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402111514.76e31d30@posting.google.com...
Greetings. I have a ten year old Toshiba 30 inch color tv. Model is
CF30c50.It has been a reliable tv until now. The screen started,for
lack of a better term,pull in on the right and have a wiggling pattern
to it. It turned itself off after that. Being a ham operator with some
electronics repair/building experience,I decided to take a look at
the innards of this. I found that,after discharging the crt,that the
HOT had shorted,and the fuseable resistor,r441,had gotten hot enough
to melt the solder joints,both on it's connection to the board,and
those of the wire harness next to it,which lead off the board(power
supply section) to the deflection yoke.A curious note about the r441
fuseable resistor was that it hadn't blown open. Another note that it
also was obvious that this particular resistor was soldered to the
board with long leads so it was raised above the board for cooling,no
heat sink of course.I repaired the board and replaced the
HOT(2SD1556/crossed to an NTE 2331),checked
the service manual voltages.Ok waveforms.Then put the thing back into
normal mode. No sound or video,only snow on the crt.After a half an
hour,it automatically shuts off. I am thinking maybe the crt has a
short,and the xray protection circuit is doing it's work??? I used to
repair my own tv's awhile back,but this is new to me. I can source a
new power supply board for 150.00 but don't know if this is worth
fixing. Any suggestions?

Daryle
WB7TNE

 

[Bill Jr]

Look particularly for a stand up board that has a TA8859 IC on it and
resolder all the connections.

Good Luck,
Bill Jr


"Ampdoc" <ampdoc@NOSPAMhotmail.com> wrote in message
news:IzcZb.35764$fE4.21462@bignews5.bellsouth.net...

Your deflection problem is a bad solder joint. Look the PCB over real well
in good light with a magnifier, look especially around components that get
hot normally or have large pins. Look real well in the Horizontal section
and you'll probably find it.


--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402191224.52d852a0@posting.google.com...
Well,Jammy. I checked your suggestions. Was looking past the problem.
Found a 5v regulator that supplies both the tuner and audio with the
output tab disconnected from the board. Odd that it would fold up out
of the board. Heating? Tv is working ok other than it still has right
side pull in on screen when first turned on.Tap the case and the
screen goes normal. Doesn't show this symptom after 15 minutes of
warmup and operation? The pull in symptom looks like inward bowing??
Thanks for the suggestions? HV shows 30.6 with probe.
Daryle
WB7TNE

"Ampdoc" <ampdoc@NOSPAMhotmail.com> wrote in message
news:<ScCWb.47546$uS3.28668@bignews4.bellsouth.net>...
The unit is supposed to shut down with a no-signal condition. Check to
see
why the tuner isn't working, look at the scan-derived power sources
that
run
the tuner, just off the flyback you should find some diodes and
fusible
resistors, check those.


--
Jammy Harbin
J & J Electronics, Inc.
227 S. 4th St.
Selmer, TN 38375
731-645-3311
"Daryle Brooks" <wb7tne350@hotmail.com> wrote in message
news:55fdc026.0402111514.76e31d30@posting.google.com...
Greetings. I have a ten year old Toshiba 30 inch color tv. Model is
CF30c50.It has been a reliable tv until now. The screen started,for
lack of a better term,pull in on the right and have a wiggling
pattern
to it. It turned itself off after that. Being a ham operator with
some
electronics repair/building experience,I decided to take a look at
the innards of this. I found that,after discharging the crt,that the
HOT had shorted,and the fuseable resistor,r441,had gotten hot enough
to melt the solder joints,both on it's connection to the board,and
those of the wire harness next to it,which lead off the board(power
supply section) to the deflection yoke.A curious note about the r441
fuseable resistor was that it hadn't blown open. Another note that
it
also was obvious that this particular resistor was soldered to the
board with long leads so it was raised above the board for
cooling,no
heat sink of course.I repaired the board and replaced the
HOT(2SD1556/crossed to an NTE 2331),checked
the service manual voltages.Ok waveforms.Then put the thing back
into
normal mode. No sound or video,only snow on the crt.After a half an
hour,it automatically shuts off. I am thinking maybe the crt has a
short,and the xray protection circuit is doing it's work??? I used
to
repair my own tv's awhile back,but this is new to me. I can source a
new power supply board for 150.00 but don't know if this is worth
fixing. Any suggestions?

Daryle
WB7TNE