HELP: Sparks at Flyback, TV shuts down

[Adrian Glaubitz]

Hi,

it's a 25inch no-name TV (bought in German supermarket, labeled "LIFETEC",
don't have model-# right here) set but looks like to be Philips
(CRT is Philips and lot of components).

When turning on from stand-by, initially everything seems normal,
then spark at flyback-transformer, directly at anode-wire. Then
TV shuts down back into stand-by and nothing happens. When
again turning on, the procedure will be the same.

I suspect excess high-voltage or bad contact of anode-cap, what
do you think ? What should I check. I have DMM, ESR-meter and
10-MHz/1-channel scope.

greetings,
Adrian

 

[LASERandDVDfan]

When turning on from stand-by, initially everything seems normal,
then spark at flyback-transformer, directly at anode-wire. Then
TV shuts down back into stand-by and nothing happens. When
again turning on, the procedure will be the same.

I suspect excess high-voltage or bad contact of anode-cap, what
do you think ?

It could be a bad anode cap, wire, or flyback. If the current isn't being
insulated from outside grounds, then the flow from the flyback to the anode can
arc to the nearest ground. - Reinhart

 

[Art]

Is the arc at the anode connection to the uthor button?? If so then
replacing the physical anode connector and rubber boot , and proper sealant
application, may suffice. However, if arcing ar the base of the anode wire,
where it exiet athe LOPT, best to replace the LOPT assembly. HV putty may
work for a peroid of time but I would not trust it.
"LASERandDVDfan" <laseranddvdfan@aol.com> wrote in message
news:20040518102222.24879.00001624@mb-m18.aol.com...

When turning on from stand-by, initially everything seems normal,
then spark at flyback-transformer, directly at anode-wire. Then
TV shuts down back into stand-by and nothing happens. When
again turning on, the procedure will be the same.

I suspect excess high-voltage or bad contact of anode-cap, what
do you think ?

It could be a bad anode cap, wire, or flyback. If the current isn't being
insulated from outside grounds, then the flow from the flyback to the
anode can
arc to the nearest ground. - Reinhart

 

[RonKZ650]

Is the arc at the anode connection to the uthor button?? If so then
replacing the physical anode connector and rubber boot , and proper sealant
application, may suffice. However, if arcing ar the base of the anode wire,
where it exiet athe LOPT, best to replace the LOPT assembly. HV putty may
work for a peroid of time but I would not trust it.

If it's arcing where the anode wire exits the transformer, I've had good luck
building a block or using good tape as a temporary mold around the area and
filling it with JB weld epoxy. The stuff works great as an insulator after dry.
If it's cracked plastic on the transformer itself, you need a new transformer.
I highly doubt the problem is from too much HV. Even it the HV was 40k volts,
all that happens normally is instant shutdown or shorting of the horiz output
transistor. By the way Art, what the heck does LOPT stand for? I've been around
26 years in the business and never heard anyone else refer to the flyback with
this designation.
Ron

 

[VenomĽ8]

Line OutPut Tower? Just a guess



"RonKZ650" <ronkz650@aol.comnospam> wrote in message
news:20040518161838.27600.00001473@mb-m05.aol.com...
: >Is the arc at the anode connection to the uthor button?? If so then
: >replacing the physical anode connector and rubber boot , and proper sealant
: >application, may suffice. However, if arcing ar the base of the anode wire,
: >where it exiet athe LOPT, best to replace the LOPT assembly. HV putty may
: >work for a peroid of time but I would not trust it.
:
: If it's arcing where the anode wire exits the transformer, I've had good luck
: building a block or using good tape as a temporary mold around the area and
: filling it with JB weld epoxy. The stuff works great as an insulator after
dry.
: If it's cracked plastic on the transformer itself, you need a new transformer.
: I highly doubt the problem is from too much HV. Even it the HV was 40k volts,
: all that happens normally is instant shutdown or shorting of the horiz output
: transistor. By the way Art, what the heck does LOPT stand for? I've been
around
: 26 years in the business and never heard anyone else refer to the flyback with
: this designation.
: Ron

 

[Ricky Eck]

LOPT = Line OutPut Transformer

Rick

"VenomĽ8" <Spam@spam.Ham> wrote in message
news:Qrvqc.2438$_V4.1637@read1.cgocable.net...

Line OutPut Tower? Just a guess



"RonKZ650" <ronkz650@aol.comnospam> wrote in message
news:20040518161838.27600.00001473@mb-m05.aol.com...
: >Is the arc at the anode connection to the uthor button?? If so then
: >replacing the physical anode connector and rubber boot , and proper
sealant
: >application, may suffice. However, if arcing ar the base of the anode
wire,
: >where it exiet athe LOPT, best to replace the LOPT assembly. HV putty
may
: >work for a peroid of time but I would not trust it.
:
: If it's arcing where the anode wire exits the transformer, I've had good
luck
: building a block or using good tape as a temporary mold around the area
and
: filling it with JB weld epoxy. The stuff works great as an insulator
after
dry.
: If it's cracked plastic on the transformer itself, you need a new
transformer.
: I highly doubt the problem is from too much HV. Even it the HV was 40k
volts,
: all that happens normally is instant shutdown or shorting of the horiz
output
: transistor. By the way Art, what the heck does LOPT stand for? I've been
around
: 26 years in the business and never heard anyone else refer to the
flyback with
: this designation.
: Ron

 

[VenomĽ8]

That's it, I was thinking that the referal was to the FlyBack output. I've
referred to it as the 'tower' sometimes, especially when I work in the
automotive industry, and coil outputs were usually refered to as the 'tower'


"Ricky Eck" <lizard7151971@verizon.net> wrote in message
newsxvqc.85113$sK3.36374@nwrddc03.gnilink.net...
: LOPT = Line OutPut Transformer
:
: Rick
:
: "VenomĽ8" <Spam@spam.Ham> wrote in message
: news:Qrvqc.2438$_V4.1637@read1.cgocable.net...
: > Line OutPut Tower? Just a guess
: >
: >
: >
: > "RonKZ650" <ronkz650@aol.comnospam> wrote in message
: > news:20040518161838.27600.00001473@mb-m05.aol.com...
: > : >Is the arc at the anode connection to the uthor button?? If so then
: > : >replacing the physical anode connector and rubber boot , and proper
: sealant
: > : >application, may suffice. However, if arcing ar the base of the anode
: wire,
: > : >where it exiet athe LOPT, best to replace the LOPT assembly. HV putty
: may
: > : >work for a peroid of time but I would not trust it.
: > :
: > : If it's arcing where the anode wire exits the transformer, I've had good
: luck
: > : building a block or using good tape as a temporary mold around the area
: and
: > : filling it with JB weld epoxy. The stuff works great as an insulator
: after
: > dry.
: > : If it's cracked plastic on the transformer itself, you need a new
: transformer.
: > : I highly doubt the problem is from too much HV. Even it the HV was 40k
: volts,
: > : all that happens normally is instant shutdown or shorting of the horiz
: output
: > : transistor. By the way Art, what the heck does LOPT stand for? I've been
: > around
: > : 26 years in the business and never heard anyone else refer to the
: flyback with
: > : this designation.
: > : Ron
: >
: >
:
:

 

[Adrian G.]

Hi Ron,

If it's arcing where the anode wire exits the transformer,

Yes, that's exactly where the spark comes out. It arcs from the
wire-output to the flybacks housing, then TV shuts down.

I've had good luck
building a block or using good tape as a temporary mold around the area and
filling it with JB weld epoxy. The stuff works great as an insulator after dry.
If it's cracked plastic on the transformer itself, you need a new transformer.
I highly doubt the problem is from too much HV. Even it the HV was 40k volts,
all that happens normally is instant shutdown or shorting of the horiz output
transistor. By the way Art, what the heck does LOPT stand for? I've been around
26 years in the business and never heard anyone else refer to the flyback with
this designation.
Ron

So you guys think it's due to insufficient isolation ? So I'd better
check this first before checking all components of the HV-Section and
removing and cleaning the anode-cap (which I really don't want to,
they are quite fragile on some sets).

greetings,
Adrian

 

[H. R. Bob Hofmann]

adi007@germanynet.de (Adrian G.) wrote in message news:<cf6565b6.0405182315.2bff6b54@posting.google.com>...

Hi Ron,

If it's arcing where the anode wire exits the transformer,

Yes, that's exactly where the spark comes out. It arcs from the
wire-output to the flybacks housing, then TV shuts down.

I've had good luck
building a block or using good tape as a temporary mold around the area and
filling it with JB weld epoxy. The stuff works great as an insulator after dry.
If it's cracked plastic on the transformer itself, you need a new transformer.
I highly doubt the problem is from too much HV. Even it the HV was 40k volts,
all that happens normally is instant shutdown or shorting of the horiz output
transistor. By the way Art, what the heck does LOPT stand for? I've been around
26 years in the business and never heard anyone else refer to the flyback with
this designation.
Ron

So you guys think it's due to insufficient isolation ? So I'd better
check this first before checking all components of the HV-Section and
removing and cleaning the anode-cap (which I really don't want to,
they are quite fragile on some sets).

greetings,
Adrian

If you are lucky, the shutdown has worked before any serious damage
has occurred. When you build up the insulation around the anode wire
where it exits the flyback xformer, use a strong light and a
magnifying glass to look at the surface of the flyback where the spark
occurred. If it has happend a few times, there may be a carbon
deposit on the surface of the transformer that will repeatedly cause
the arc to occur, even with new insulation added. Try to clean (very
carefully) the surface of the flyback using clean water or alcohol in
the area where the arc occurred. Then use a hairdryer to really dry
the area before applying silicon rubber or whatever else you will be
using to build up the insulation. When you have added the insulation,
let it dry THOROUGHLY before turning the set back on, like 24 hours.
It wouldn't hurt to have a fan blowing gently over the set while the
new insulation is drying or curing. Then turn the set on in a
darkened/blacked-out room and see what happens. Even if there is no
arc, there could still be a leakage path that would show up as a
corona discharge in the dark. If there is any sign of leakage, turn
the set off and add more insulation, another 24 hours, etc.

H. R. (Bob) Hofmann