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whats inside a FBT......this

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paris

Thu Jan 03 2013, 01:15AM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

Hi, I opened up an ave size TV FBT and hacked into it with a hammer and punch/chisel , eventually finding grey resin around the sec and pri coils.
The white ceramic is a job to get thru.

removed pri because thats nothing interesting and then I was left with sec.

I had to use dremel to grind out centre and fret saw to cut thru grey resin.

the coil is protected by layers of clear poly whatsit,both on the outside and centre.

the remaining coil =
24mm od
20mm id
28mm tall
21mm actual coil height

this was just an exercise to see whats in FBT. I have no idea what size wire that is buts its small. The smallest wire Ive seen is on a comp hard drive , theres super fine wire on the moving arm that travels across the disc.

GrantX

Fri Jan 04 2013, 04:06AM

Registered Member #4074 Joined: Mon Aug 29 2011, 06:58AM
Location: Australia
Posts: 335

Interesting. Any idea of the number of turns, or at least the number of layers and a rough estimate of the turns on each layer?

I had always thought that the secondary of a modern flyback was wound as several split coils connected in series via diodes. Did you find any diodes or caps inside the epoxy?

paris

Fri Jan 04 2013, 07:00AM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

yea there was debri flying everywhere, I dont recommend doing it just know that it can be done.
Ive seen x ray of a marx gen some where on this site but havent seen 1 of a FBT, maybe the ceramic is too dense Id say.

The wire is finer than ignition coil wire ,its like silk. dont ask how HV gets to output lead because I didnt see , too busy chippen...

inside dia of coil is 20.3 or so and between each layer theres the clear plastic sheets . I wrote the dimensions hoping some one could estimate ...how many layers fit in 1.7 mm??

its hard to say, my next mad idea would be to find out ;)

all diagrams Ive seen have diodes etc I was thinking maybe the ceramic has silicon closest to the sec. large FBT have clearly cap and diode showing in the shape of their casing.

on the tuning side with the pots theres a ceramic sheet with the tracking for the pots.
everything is definitely HV heavy duty.

it would be a task to rewind onto another former . Im wondering who sells this wire.
the winding machine must be impressive to see.
I just thought it would be interesting sight to see a naked secondary coil

paris

Fri Jan 04 2013, 11:45PM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

heres ignition coil wire .090mm = BS 39 = SWG 43 = 3.531 mils

paris

Fri Jan 04 2013, 11:53PM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

heres the FBT wire = .035 mm = .001378" dia . what size that is I dont know but will try to find out .

the plastic sheets are .074 mm thick

the centre pretty much fell out ... after I wrenched it!

21mm / .035 = 600 turns per layer ,thats only approx

Ash Small

Sat Jan 05 2013, 01:46PM

Registered Member #3414 Joined: Sun Nov 14 2010, 05:05PM
Location: UK
Posts: 4245

0.04mm is about the smallest diameter used by coil winding machines (generally).

I worked in a coil winding factory for a bit, and they said their machines had trouble winding 0.04mm dia., and it kept snapping.

paris

Sat Jan 05 2013, 07:21PM

Registered Member #3042 Joined: Wed Jul 28 2010, 12:36AM
Location:
Posts: 121

I would say your right , hard to measure this stuff so Im probably crushing it when I measure.

What size is this stuff called????

I cant find anything that small on AWG gauge etc

the winding machine must be so delicate , but imagine how many of these coils were made thru the years, the rejects bin must be huge.

Proud Mary

Sat Jan 05 2013, 08:13PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Solderable polyester enameled round copper wire diameter 0.03 mm is available in metric tonnes from Beijing Tianyulonghua Trade Co., China.

Patrick

Sun Jan 13 2013, 05:35AM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

there may not be a AWG equivelent... but still nice work, i did the same destructive analysis back in high school in 1998...

not only are these difficult to wind, but you dont even have to break the strand, just stretch it to the point micro-scopic striations appear in the insulation, then your boned.

Dragon64

Mon Jan 14 2013, 05:36PM

Registered Member #1438 Joined: Sat Apr 12 2008, 12:57AM
Location: Canada
Posts: 218

If the flyback you dissected was a DST, I would love to see the internal diodes if it managed to survive being chipped away from the epoxy. :)

The above patent image is the best representation of what it would truly looks like without the epoxy.

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