Panasonic vertical collapse

C

Charlie Bress

Guest
The TV is a Panasonic CT-27G22V.
It has developed a consistent failure of the vertical sweep.
When turned on cold the sweep is normal for a short period of time - maybe a
minute to five minutes.

Then the sweep collapses to a single horizontal line. It may correct in a
few seconds or it can be restored by using the remote and powering off and
on a time or two.

After the sweep is restored, it will remain stable as long as the set is on.

Apparently, this is a temperature related problem. I imagine that to trouble
shoot this problem will require a heat gun and/or cold spray. Before I go
after this a couple of questions.

Is this circuitry surface mount or PTH? Are the probable culprits discrete
components or something integrated and likely hard to obtain? And, does this
set have a known history of this failure mode that is documented somewhere?

Thanks
Charlie
 
Pull off the back and remove out the chassis
so you can work underneath it.
Now get out your mag glass and look at the base
of the Vertical output IC you will see bad dry
solder joints.Remove the old and reflow with new
solder it might also be a good idea to replace
the 3 or so filter caps in and around the heatsink.

Good Luck

kip

--
"Watch the return E-Mail addy its false"
"Charlie Bress" <Here-I-am@the-last-moment.com> wrote in message
news:7f-dnZRgId-w-PndRVn-gg@comcast.com...
The TV is a Panasonic CT-27G22V.
It has developed a consistent failure of the vertical sweep.
When turned on cold the sweep is normal for a short period of time - maybe
a
minute to five minutes.

Then the sweep collapses to a single horizontal line. It may correct in a
few seconds or it can be restored by using the remote and powering off and
on a time or two.

After the sweep is restored, it will remain stable as long as the set is
on.

Apparently, this is a temperature related problem. I imagine that to
trouble
shoot this problem will require a heat gun and/or cold spray. Before I go
after this a couple of questions.

Is this circuitry surface mount or PTH? Are the probable culprits discrete
components or something integrated and likely hard to obtain? And, does
this
set have a known history of this failure mode that is documented
somewhere?

Thanks
Charlie
Click to expand...
 
Using the set with problems, will usually result in more serious and
expensive repairs. When the thermo sensitive parts fail completely, they can
cause more damage.

Going by your description, this is more than likely a thermo sensitive part,
rather than a cold solder connection. Cold solders are sensitive to flexing,
bending, or tapping on the circuit board, and are rarely thermo sensitive.
When they become very bad, they may not make contact anymore, and act as an
opened circuit most of, or all the time.

It is best to find the defective parts rather than play darts by spending a
lot of money and time for parts the set does not require. If the part is
thermo sensitive, you should be able to find it by heating and cooling the
suspected parts. Most of the time, it is the capacitors that become thermo
sensitive. On the odd occasion, I have had other types of components become
thermo sensitive as well.

If your set is less than about 5 to 7 years old, most of the parts will be
SMD types. The major IC's will most likely be the standard types that can be
soldered easily with a fine tipped soldering iron. If the set is newer than
about 3 to 5 years, most of the IC's and transistors will also be SMD types,
and proper soldering station equipment will be required to remove, and
install new ones. Only most of the high current type devices will mostly be
the standard solder types. This is also for the large electrolytic caps,
high wattage resistors, and high power semiconductors.

The newer generation of appliances (TV's, radios, DVD players, VCR's, and
etc) that have been coming out now, are using even smaller types of SMD
devices. The newer appliances are being build up on circuit boards that are
using the same engineering techniques as mother boards in computers. Some of
us are calling these components "Sub SMD" type components. It is at the
point where it will be impossible to do most of the soldering with any type
of conventional soldering tools. At the factory service level, when the sets
are under warranty, the service centres are usually changing the complete
board, rather than investing the time to troubleshoot and service these at
the component level, if the fault is more involved than a simple type of
part change or fix. Some of these new generation boards are infact too
complicated to do standard bench type troubleshooting, when there are in
debt problems.

Cold solder connections on these new generations of boards are sometimes
impossible to find by conventional means. The point to point opened
connection has to be determined, and an outboard piece of wire must be
tacked on to complete the circuit, if this is even possible to do. These
boards can be multilayered up to 4 and even 8 layers in many of the new
devices.

The layers can interconnect to each other at different levels in order to
connect to their associated components. This type of design can allow for
much smaller construction, and higher density per area on the board. When
there is an opened circuit between the layers, a tech can spend many hours
to trace down, and find a way to service this type of fault. It ends up
being much cheaper to either replace the board, or scrap the set.

The next generation of sets, and what is coming out on many of the new
boards is embedded component technology. This is where components will be
embedded as part of the board itself. This will allow for the boards to be
flatter, and require less vertical clearance. This has been happening in
many of the industrial type circuit boards for a few years now. This
technique will be very common on the newer computer boards, and appliances.
If you open up some of the new portable pocket type CD players and portable
radios, you will see a lot of this new technology being used. These are
almost not serviceable at all at the circuit board level with this type of
technology.

--

Greetings,

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


"Charlie Bress" <Here-I-am@the-last-moment.com> wrote in message
news:7f-dnZRgId-w-PndRVn-gg@comcast.com...
The TV is a Panasonic CT-27G22V.
It has developed a consistent failure of the vertical sweep.
When turned on cold the sweep is normal for a short period of time - maybe a
minute to five minutes.

Then the sweep collapses to a single horizontal line. It may correct in a
few seconds or it can be restored by using the remote and powering off and
on a time or two.

After the sweep is restored, it will remain stable as long as the set is on.

Apparently, this is a temperature related problem. I imagine that to trouble
shoot this problem will require a heat gun and/or cold spray. Before I go
after this a couple of questions.

Is this circuitry surface mount or PTH? Are the probable culprits discrete
components or something integrated and likely hard to obtain? And, does this
set have a known history of this failure mode that is documented somewhere?

Thanks
Charlie
 
Thanks Jerry
The set is about 6 years old, so there is hope of being repairable. I have
been holding out for a solid failure, but this darn thing has been
stubbornly acting like this for about 3 months. I have been retired from the
electronics industry for a dozen years now and have not been keeping up with
the latest technology changes.

I haven't discounted the bad solder joint yet as the thing almost acts like
it has a particular temperature at which it fails. I am painfully aware of
the problems that the industry has had with plated through connections on
multi-level boards that fail as the board, with all its various coefficients
of expansion tries to tear itself apart. I was sort of hoping that someone
had run across this problem and could pin point the fix. Oh well, no such
luck. A quick and dirty Google search did not find any thing either.

Charlie


"Jerry G." <jerryg50@hotmail.com> wrote in message
news:c41str$2ji$1@news.eusc.inter.net...
Using the set with problems, will usually result in more serious and
expensive repairs. When the thermo sensitive parts fail completely, they
can
cause more damage.

Going by your description, this is more than likely a thermo sensitive
part,
rather than a cold solder connection. Cold solders are sensitive to
flexing,
bending, or tapping on the circuit board, and are rarely thermo sensitive.
When they become very bad, they may not make contact anymore, and act as
an
opened circuit most of, or all the time.

It is best to find the defective parts rather than play darts by spending
a
lot of money and time for parts the set does not require. If the part is
thermo sensitive, you should be able to find it by heating and cooling the
suspected parts. Most of the time, it is the capacitors that become thermo
sensitive. On the odd occasion, I have had other types of components
become
thermo sensitive as well.

If your set is less than about 5 to 7 years old, most of the parts will be
SMD types. The major IC's will most likely be the standard types that can
be
soldered easily with a fine tipped soldering iron. If the set is newer
than
about 3 to 5 years, most of the IC's and transistors will also be SMD
types,
and proper soldering station equipment will be required to remove, and
install new ones. Only most of the high current type devices will mostly
be
the standard solder types. This is also for the large electrolytic caps,
high wattage resistors, and high power semiconductors.

The newer generation of appliances (TV's, radios, DVD players, VCR's, and
etc) that have been coming out now, are using even smaller types of SMD
devices. The newer appliances are being build up on circuit boards that
are
using the same engineering techniques as mother boards in computers. Some
of
us are calling these components "Sub SMD" type components. It is at the
point where it will be impossible to do most of the soldering with any
type
of conventional soldering tools. At the factory service level, when the
sets
are under warranty, the service centres are usually changing the complete
board, rather than investing the time to troubleshoot and service these at
the component level, if the fault is more involved than a simple type of
part change or fix. Some of these new generation boards are infact too
complicated to do standard bench type troubleshooting, when there are in
debt problems.

Cold solder connections on these new generations of boards are sometimes
impossible to find by conventional means. The point to point opened
connection has to be determined, and an outboard piece of wire must be
tacked on to complete the circuit, if this is even possible to do. These
boards can be multilayered up to 4 and even 8 layers in many of the new
devices.

The layers can interconnect to each other at different levels in order to
connect to their associated components. This type of design can allow for
much smaller construction, and higher density per area on the board. When
there is an opened circuit between the layers, a tech can spend many hours
to trace down, and find a way to service this type of fault. It ends up
being much cheaper to either replace the board, or scrap the set.

The next generation of sets, and what is coming out on many of the new
boards is embedded component technology. This is where components will be
embedded as part of the board itself. This will allow for the boards to be
flatter, and require less vertical clearance. This has been happening in
many of the industrial type circuit boards for a few years now. This
technique will be very common on the newer computer boards, and
appliances.
If you open up some of the new portable pocket type CD players and
portable
radios, you will see a lot of this new technology being used. These are
almost not serviceable at all at the circuit board level with this type of
technology.

--

Greetings,

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


"Charlie Bress" <Here-I-am@the-last-moment.com> wrote in message
news:7f-dnZRgId-w-PndRVn-gg@comcast.com...
The TV is a Panasonic CT-27G22V.
It has developed a consistent failure of the vertical sweep.
When turned on cold the sweep is normal for a short period of time - maybe
a
minute to five minutes.

Then the sweep collapses to a single horizontal line. It may correct in a
few seconds or it can be restored by using the remote and powering off and
on a time or two.

After the sweep is restored, it will remain stable as long as the set is
on.

Apparently, this is a temperature related problem. I imagine that to
trouble
shoot this problem will require a heat gun and/or cold spray. Before I go
after this a couple of questions.

Is this circuitry surface mount or PTH? Are the probable culprits discrete
components or something integrated and likely hard to obtain? And, does
this
set have a known history of this failure mode that is documented
somewhere?

Thanks
Charlie
Click to expand...
 
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