Blown HOT in Sony KVT-29SZ1
 

I have a Sony KV 29SZ1 that has a blown HOT. It is owned by my
apprentice who doesn't have a great deal of cash to throw around, so I
told him to bring it into work and we would have a go at fixing it.

The fault was simple, would not turn on. I opened it up and put the
meter across B+ - 0v. I could also hear it ticking. So the first thing
I did was pull out the HOT and test it, sure enough it was SC. I sent
the the young fella out to buy a new HOT which turned out to be AU$30.

So, the question I ask is: Is there in easy way to tell if the LOPT is
the reason the HOT has failed? I don't really want to put the new part
in if it is going to blow straight away. I was thinking about putting
it in and bringing up the power slowly from a variac. Will this help?

TAI,

AP

Blown HOT in Sony KVT-29SZ1
 

Ringer Testing of the LOPT should convince you if indeed it is operational
or defective. Commercial instruments are available to do the task. Inspect
the main circuit board to confirm the solder connections at the horizontal
driver transistor and transformer as well as those at the LOPT itself.
Confirm the B+ is correctly regulated at the appropriate voltage. ESR the
caps in the set, esp in the power supply circuits.
"ap" wrote in message
...
I have a Sony KV 29SZ1 that has a blown HOT. It is owned by my
apprentice who doesn't have a great deal of cash to throw around, so I
told him to bring it into work and we would have a go at fixing it.

The fault was simple, would not turn on. I opened it up and put the
meter across B+ - 0v. I could also hear it ticking. So the first thing
I did was pull out the HOT and test it, sure enough it was SC. I sent
the the young fella out to buy a new HOT which turned out to be AU$30.

So, the question I ask is: Is there in easy way to tell if the LOPT is
the reason the HOT has failed? I don't really want to put the new part
in if it is going to blow straight away. I was thinking about putting
it in and bringing up the power slowly from a variac. Will this help?

TAI,

AP

Hi I have a Sony KV 29SZ1, (Perth Australia) with a ticking or clicking noise, no picture and no sound. It looks like at this stage the problem is in a fuse, my question is how can you tell which one it is, I can hear the thing ticking away but I just can't locate it (I have removed the TV cover)...


[QUOTE
I have a Sony KV 29SZ1 that has a blown HOT. It is owned by my
apprentice who doesn't have a great deal of cash to throw around, so I
told him to bring it into work and we would have a go at fixing it.

The fault was simple, would not turn on. I opened it up and put the
meter across B+ - 0v. I could also hear it ticking. So the first thing
I did was pull out the HOT and test it, sure enough it was SC. I sent
the the young fella out to buy a new HOT which turned out to be AU$30.

So, the question I ask is: Is there in easy way to tell if the LOPT is
the reason the HOT has failed? I don't really want to put the new part
in if it is going to blow straight away. I was thinking about putting
it in and bringing up the power slowly from a variac. Will this help?

TAI,

AP[/i][/color][/quote]

Blown HOT in Sony KVT-29SZ1
 

sigmma:
No offence intended, but based on your inquiry you would be best advised to
IMMJEDIATELY replace the TV cover and at the very least TAKE it to a repair
shop for a repair cost estimate by a tech that has actually opened er up and
performed some technical troubleshooting and testing so you can make an
intelligent repair decision with facts instead of wild guesses.
The insides of televisions are a dangerous place.... if you want to research
this further you should go to the website for this newsgroup at
http://www.repairfaq.org/
there with some searching you will find a wealth of repair data and
IMPORTANT SAFETY information.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -


"sigmma" wrote in message
Hi I have a Sony KV 29SZ1, (Perth Australia) with a ticking or clicking
noise, no picture and no sound. It looks like at this stage the problem
is in a fuse, my question is how can you tell which one it is, I can
hear the thing ticking away but I just can't locate it (I have removed
the TV cover)...
sigmma

Blown HOT in Sony KVT-29SZ1
 

"sigmma" wrote in message
...

Hi I have a Sony KV 29SZ1, (Perth Australia) with a ticking or clicking
noise, no picture and no sound. It looks like at this stage the problem
is in a fuse, my question is how can you tell which one it is, I can
hear the thing ticking away but I just can't locate it (I have removed
the TV cover)...


I have a Sony KV 29SZ1 that has a blown HOT. It is owned by my
apprentice who doesn't have a great deal of cash to throw around, so I
told him to bring it into work and we would have a go at fixing it.

The fault was simple, would not turn on. I opened it up and put the
meter across B+ - 0v. I could also hear it ticking. So the first thing
I did was pull out the HOT and test it, sure enough it was SC. I sent
the the young fella out to buy a new HOT which turned out to be AU$30.

So, the question I ask is: Is there in easy way to tell if the LOPT is
the reason the HOT has failed? I don't really want to put the new part
in if it is going to blow straight away. I was thinking about putting
it in and bringing up the power slowly from a variac. Will this help?

TAI,

AP[/i Wrote:



--
sigmma[/color]

Replace the H-transistor, but do not solder the collector terminal - route
this via a 60W bulb which will limit the current if the LOPT has shorted
turns. If this arrangement fails to develop a voltage across the LOPT
primary - don't despair, it could be a S/C rectifier for a scan derived
supply, just follow the tracks away from the LOPT and look for diodes to
test. Another common cause of H-transistor failure is the flybak tuning
capacitor - this is often a disc-ceramic type (normally go S/C and
split/burn!) the regular high voltage wound foil types commonly fail O/C and
allow the peak flyback voltage to exceed the H-transistor's Vceo!

Caution - examine the flyback tuning caps first - the current limiting lamp
won't protect the transistor from excessive flyback if it fires up!!!

Blown HOT in Sony KVT-29SZ1
 

Also resolder theconnections of the LOPT, H-Driver Transformer, and Driver
Transistor. Seen way too many of their sets with funky solder conections
around those areas. Loss of drive can cause the output to blow.
"ian field" wrote in message
...

"sigmma" wrote in message
...

Hi I have a Sony KV 29SZ1, (Perth Australia) with a ticking or clicking
noise, no picture and no sound. It looks like at this stage the problem
is in a fuse, my question is how can you tell which one it is, I can
hear the thing ticking away but I just can't locate it (I have removed
the TV cover)...


I have a Sony KV 29SZ1 that has a blown HOT. It is owned by my
apprentice who doesn't have a great deal of cash to throw around, so I
told him to bring it into work and we would have a go at fixing it.

The fault was simple, would not turn on. I opened it up and put the
meter across B+ - 0v. I could also hear it ticking. So the first thing
I did was pull out the HOT and test it, sure enough it was SC. I sent
the the young fella out to buy a new HOT which turned out to be AU$30.

So, the question I ask is: Is there in easy way to tell if the LOPT is
the reason the HOT has failed? I don't really want to put the new part
in if it is going to blow straight away. I was thinking about putting
it in and bringing up the power slowly from a variac. Will this help?

TAI,

AP[/i Wrote:



--
sigmma

Replace the H-transistor, but do not solder the collector terminal - route
this via a 60W bulb which will limit the current if the LOPT has shorted
turns. If this arrangement fails to develop a voltage across the LOPT
primary - don't despair, it could be a S/C rectifier for a scan derived
supply, just follow the tracks away from the LOPT and look for diodes to
test. Another common cause of H-transistor failure is the flybak tuning
capacitor - this is often a disc-ceramic type (normally go S/C and
split/burn!) the regular high voltage wound foil types commonly fail O/C
and allow the peak flyback voltage to exceed the H-transistor's Vceo!

Caution - examine the flyback tuning caps first - the current limiting
lamp won't protect the transistor from excessive flyback if it fires up!!!
[/color]

Blown HOT in Sony KVT-29SZ1
 

On Tue, 16 May 2006 23:02:28 GMT, "ian field"
wrote:


"sigmma" wrote in message
...

sigmma

Replace the H-transistor, but do not solder the collector terminal - route
this via a 60W bulb which will limit the current if the LOPT has shorted
turns. If this arrangement fails to develop a voltage across the LOPT
primary - don't despair, it could be a S/C rectifier for a scan derived
supply, just follow the tracks away from the LOPT and look for diodes to
test. Another common cause of H-transistor failure is the flybak tuning
capacitor - this is often a disc-ceramic type (normally go S/C and
split/burn!) the regular high voltage wound foil types commonly fail O/C and
allow the peak flyback voltage to exceed the H-transistor's Vceo!

Caution - examine the flyback tuning caps first - the current limiting lamp
won't protect the transistor from excessive flyback if it fires up!!!


Good question on that HV caps in horizontal circuit, what is the
method of checking them? I have capacitance meter but I know better
not to trust that, cap could fail under load (even instantly) and pass
a cap meter test?

Cheers, Wizard

Blown HOT in Sony KVT-29SZ1
 

"Art" wrote in message
. ..
Also resolder theconnections of the LOPT, H-Driver Transformer, and Driver
Transistor. Seen way too many of their sets with funky solder conections
around those areas. Loss of drive can cause the output to blow.


That's lead free solder for you! Since its introduction reliability has
plummeted so far that some 5x as much electrical equipment is going into
landfill!!!

Lead was mined from the earth in the first place, and that's eventually
where itends up back. Just like the run off rain and the weather washes from
lead roofing and the pellets from 12bore guns used for bloodsports - which
the brain-dead beaurocrats seem to have overlooked!!!

Blown HOT in Sony KVT-29SZ1
 

"Jason D." wrote in message
...
On Tue, 16 May 2006 23:02:28 GMT, "ian field"
wrote:


"sigmma" wrote in message
...

sigmma

Replace the H-transistor, but do not solder the collector terminal - route
this via a 60W bulb which will limit the current if the LOPT has shorted
turns. If this arrangement fails to develop a voltage across the LOPT
primary - don't despair, it could be a S/C rectifier for a scan derived
supply, just follow the tracks away from the LOPT and look for diodes to
test. Another common cause of H-transistor failure is the flybak tuning
capacitor - this is often a disc-ceramic type (normally go S/C and
split/burn!) the regular high voltage wound foil types commonly fail O/C
and
allow the peak flyback voltage to exceed the H-transistor's Vceo!

Caution - examine the flyback tuning caps first - the current limiting
lamp
won't protect the transistor from excessive flyback if it fires up!!!


Good question on that HV caps in horizontal circuit, what is the
method of checking them? I have capacitance meter but I know better
not to trust that, cap could fail under load (even instantly) and pass
a cap meter test?

Cheers, Wizard

Given the cost of the H-transistor, test by replacement is probably the
safer option.

Blown HOT in Sony KVT-29SZ1
 

"ian field" wrote:
"Art" wrote in message
...
Also resolder theconnections of the LOPT, H-Driver Transformer, and Driver
Transistor. Seen way too many of their sets with funky solder conections
around those areas. Loss of drive can cause the output to blow.


That's lead free solder for you! Since its introduction reliability has
plummeted so far that some 5x as much electrical equipment is going into
landfill!!!

Do you have a reference for that figure?


Tim
--
Did I really still have that sig?

Blown HOT in Sony KVT-29SZ1
 

"Tim Auton" wrote in message
...
"ian field" wrote:
"Art" wrote in message
m...
Also resolder theconnections of the LOPT, H-Driver Transformer, and
Driver
Transistor. Seen way too many of their sets with funky solder conections
around those areas. Loss of drive can cause the output to blow.


That's lead free solder for you! Since its introduction reliability has
plummeted so far that some 5x as much electrical equipment is going into
landfill!!!

Do you have a reference for that figure?


Tim
--
Did I really still have that sig?

Its just a guess - but I've just been to a refuse container site to get some
salvage parts, they have great steel cages lined up in rows full of scrap
TVs, monitors and other electrical goods, and this is only a small town!!!

Daniel Many thanks for your advice, I know that the inside of Tvs are a really dangerous place, thats why I have decided to unplug the unit from the wall before touching the flyback with my bare hands.....just kidding!!!
now seriously, since I dont have a diagram for my Tv I have decided to search for a faulty unit on ebay, Do you guys think that if someone is selling a faulty unit and the fault being something like colour fading, then the cause would be an aging tube and the chassis will be more o less fine.....so if I replace the chassis from a another tv then I'll have my Tv back....posible?????

Blown HOT in Sony KVT-29SZ1
 

"sigmma" wrote in message
...

sigmma:
No offence intended, but based on your inquiry you would be best
advised to
IMMJEDIATELY replace the TV cover and at the very least TAKE it to a
repair
shop for a repair cost estimate by a tech that has actually opened er
up and
performed some technical troubleshooting and testing so you can make
an
intelligent repair decision with facts instead of wild guesses.
The insides of televisions are a dangerous place.... if you want to
research
this further you should go to the website for this newsgroup at
http://www.repairfaq.org/
there with some searching you will find a wealth of repair data and
IMPORTANT SAFETY information.
--
Best Regards,
Daniel Sofie
Electronics Supply & Repair



Daniel Many thanks for your advice, I know that the inside of Tvs are a
really dangerous place, thats why I have decided to unplug the unit from
the wall before touching the flyback with my bare hands.....just
kidding!!!
now seriously, since I dont have a diagram for my Tv I have decided to
search for a faulty unit on ebay, Do you guys think that if someone is
selling a faulty unit and the fault being something like colour fading,
then the cause would be an aging tube and the chassis will be more o
less fine.....so if I replace the chassis from a another tv then I'll
have my Tv back....posible?????


--
sigmma

Some less reputable service engineers make their living this way.