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Flyback question

T

Thomas Abell

Jan 1, 1970
0
Can the cracked (and separating) core of a FBT cause a problem in a Zenith
television? I'm not speaking of the split between the top and bottom, but
the bottom section is cracked and pulling apart. Thanks.
 
D

Doug

Jan 1, 1970
0
I assume you must be having a problem since you have the set open.
In Magnavox's when the core broke caused certain secondaries to
increase in voltage which upset agc,. horz sync causing pulling of
picture and intermitted loose of horz sync.
 
S

Sam Goldwasser

Jan 1, 1970
0
Doug said:
I assume you must be having a problem since you have the set open.
In Magnavox's when the core broke caused certain secondaries to
increase in voltage which upset agc,. horz sync causing pulling of
picture and intermitted loose of horz sync.

Yes, a cracked core can cause all sorts of problems. You can try carefully
gluing or clamping it back together as a temporary test. Minimize any
gaps by making sure there is minimal glue between the sections. If
significant chunks are missing, just replace it.

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J

Jerry G.

Jan 1, 1970
0
If there is a crack in the core, or in the windings area, the flyback should
be replaced.

--

Jerry G.
=====

Can the cracked (and separating) core of a FBT cause a problem in a Zenith
television? I'm not speaking of the split between the top and bottom, but
the bottom section is cracked and pulling apart. Thanks.
 
T

Thomas Abell

Jan 1, 1970
0
Yes there is a problem. The set came in with the HOT shorted and FX3403
open. (This set uses the 9-1268 sweep module.) I replaced them and powered
the set up with the old light bulb trick, while monitoring the waveform at
the collector of the HOT. It was loaded badly, indicating it was likely a
FBT failure. I got one from Tritronics (generic as the OEM's are NLA). The
set worked for about 30 seconds then went into shutdown. After reading
about the issue with generic Zenith FBT's I changed a resistor as suggested
which worked. However after about an hour the set started blowing fx3403
again...and again. Nothing appeared abnormal in the operation of the set.
It was near perfect. I backtracked and removed the new flyback for a look.
That's when I found the bottom section of the fly cracked and separating. I
have another on order in hopes that this dog will stop barking at me!
Thanks for the feedback.
 
T

Techforce

Jan 1, 1970
0
If the crack is symmetrical, with no major chunks missing that cause a
significant gap, you can carefully remove the clip holding the ferrite in
place, and
glue or epoxy the breal back in place - then place the clip on, which will
help the break squeeze together better during the cure. J-B welds work real
good or also hot glue.

Side Note: You can also transplant the Ferrite from the old flyback to the
new as long as its close or about the same dimensions. Removing the ferrite
on an OEM flyback can be a chore because of the epoxy they use to hold it in
place. We have found a heat gun, like the type that strips paint , will help
dislodge the cores on the OEM flybacks, with some patience and care.



| Yes there is a problem. The set came in with the HOT shorted and FX3403
| open. (This set uses the 9-1268 sweep module.) I replaced them and
powered
| the set up with the old light bulb trick, while monitoring the waveform at
| the collector of the HOT. It was loaded badly, indicating it was likely a
| FBT failure. I got one from Tritronics (generic as the OEM's are NLA).
The
| set worked for about 30 seconds then went into shutdown. After reading
| about the issue with generic Zenith FBT's I changed a resistor as
suggested
| which worked. However after about an hour the set started blowing fx3403
| again...and again. Nothing appeared abnormal in the operation of the set.
| It was near perfect. I backtracked and removed the new flyback for a
look.
| That's when I found the bottom section of the fly cracked and separating.
I
| have another on order in hopes that this dog will stop barking at me!
| Thanks for the feedback.
|
|
| | >I assume you must be having a problem since you have the set open.
| > In Magnavox's when the core broke caused certain secondaries to
| > increase in voltage which upset agc,. horz sync causing pulling of
| > picture and intermitted loose of horz sync.
| >
|
|
 
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