I am going insane working on this same TV, but for this groups sake, I
will only ask the following: How are you supposed to properly check a
flyback transformer? I would think both primary and secondary sides
should be checked. Wouldn't a defect in the secondary cause problems in
the main power supply, like blown fuse, etc? I had one checked by a
tech I know, and he only checked the primary (B+) winding. The set
keeps blowing fuse and shutting down by the way. I am a beginner in
repair with good understanding of basic electronics, but have a long,
long way to go before understanding exactly how a television operates.
Suggestions on training material exremely welcome. I really am ate up
with it. Thank you very much group. I have visited other repair forums,
but ya'll are awesome.

writes:

I am going insane working on this same TV, but for this groups sake, I
will only ask the following: How are you supposed to properly check a
flyback transformer? I would think both primary and secondary sides
should be checked. Wouldn't a defect in the secondary cause problems in
the main power supply, like blown fuse, etc? I had one checked by a
tech I know, and he only checked the primary (B+) winding. The set
keeps blowing fuse and shutting down by the way. I am a beginner in
repair with good understanding of basic electronics, but have a long,
long way to go before understanding exactly how a television operates.
Suggestions on training material exremely welcome. I really am ate up
with it. Thank you very much group. I have visited other repair forums,
but ya'll are awesome.

When you say it blows fuses, do you mean all the time immediately?

Or, after some random period of operating perfectly normally?

If by "checking the primary winding", you mean doing a "ring test" or
something similar, that can determine whether there are any hard
short circuit failures but not opens and probably not a damaged core.
It also won't find failures that happen after running awhile and heating
up, or from the high voltages running around inside.

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I use a Sencore VA62 that I picked up on Ebay for $200. It has a ring test
and a drive signal. The ring test checks the windings and the drive test
(25vpp h pulse) is used to check the HV output. You can also observe the
HOT collector output with a scope on startup and you should see a clean
pulse with no ringing or distortion. Ringing after the pulse is usually a
bad FBT.

Leonard

wrote in message
oups.com...
I am going insane working on this same TV, but for this groups sake, I
will only ask the following: How are you supposed to properly check a
flyback transformer? I would think both primary and secondary sides
should be checked. Wouldn't a defect in the secondary cause problems in
the main power supply, like blown fuse, etc? I had one checked by a
tech I know, and he only checked the primary (B+) winding. The set
keeps blowing fuse and shutting down by the way. I am a beginner in
repair with good understanding of basic electronics, but have a long,
long way to go before understanding exactly how a television operates.
Suggestions on training material exremely welcome. I really am ate up
with it. Thank you very much group. I have visited other repair forums,
but ya'll are awesome.

Much thanks for the reply Sam. The set stopped blowing the fuse when I
unplugged the green CRT. I figured shorted tube. But the TV has since
started blowing the fuse every time power up attempted. The original
problem was set not coming up. You would get the power led, here the
relay, then the set would shut down. It also kept blowing the fuse,
until I removed the green tube as stated above. But this problem
remains. Anyway, I do have a Sencore LC102, and a Sencore signal
generator with a ringing test. I am just unsure as to the correct
procedure for checking a flyback. I posted several days ago with alot
of detail of this original problem, but before I invest in a new
flyback, I want to know that at least I'm checking correctly. Thanks
again to all that have replied.

What you need to find is the primary (B+) side of theFBT to test. If you
look at a Flyback with the controls facing you, the pins are usually the
ones in the top row from left to right, usually its pins 1 & 2, but
sometimes its 1 and 3.

See this diagram of an HR Flyback just to get the concept. Here, the pins to
ring are 1 and 2
http://www.hrdiemen.es/products/inde...mas/HR8562.gif

If its a PJTV flyback, for the most part the pins layout is basicly the same
for the ones you want to ring.

Thats the ones you want to see good rings with on the Sencore. However,
this does not test the secondary, which could have a bad internal rectifier
diode or other problem. The secondary is nearly impossible to test without
placing it under a heavy load.


wrote in message
ups.com...
| Much thanks for the reply Sam. The set stopped blowing the fuse when I
| unplugged the green CRT. I figured shorted tube. But the TV has since
| started blowing the fuse every time power up attempted. The original
| problem was set not coming up. You would get the power led, here the
| relay, then the set would shut down. It also kept blowing the fuse,
| until I removed the green tube as stated above. But this problem
| remains. Anyway, I do have a Sencore LC102, and a Sencore signal
| generator with a ringing test. I am just unsure as to the correct
| procedure for checking a flyback. I posted several days ago with alot
| of detail of this original problem, but before I invest in a new
| flyback, I want to know that at least I'm checking correctly. Thanks
| again to all that have replied.
|