Rewinding a laptop's CCFL driver transformer

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Lately, one of my parents' laptop (a Packard Bell EasyNote E6305AR)
display died recently. Upon inspection, i found out that the inverter
circuit had a blown output transformer. The driver itself it's rather
simple, using a MP1015 IC which i'm told it's rather usual in these
cheap laptops.

The issue is that finding a replacement module where i live is rather
hard and i'd like trying winding an output transformer myself. The
original one was heavily epoxied - i managed to count 25 turns in the
primary, but the secondary, which was *way* thiner was in bad shape
and i couldn't get to unwind more than a few turns until it broke
under tension or i ran across a short.

Now, does anyone know an typical turn ratio for these devices (or an
output voltage)? Anything i can work with to make a good guess of the
original will be appreciated.

A datasheet for the MP1015 can be found at http://www.datasheet4u.com/download.php?id=527185
, for those interested.

 

[[email protected]]

Lately, one of my parents' laptop (a Packard Bell EasyNote E6305AR)
display died recently. Upon inspection, i found out that the inverter
circuit had a blown output transformer. The driver itself it's rather
simple, using a MP1015 IC which i'm told it's rather usual in these
cheap laptops.

The issue is that finding a replacement module where i live is rather
hard and i'd like trying winding an output transformer myself. The
original one was heavily epoxied - i managed to count 25 turns in the
primary, but the secondary, which was *way* thiner was in bad shape
and i couldn't get to unwind more than a few turns until it broke
under tension or i ran across a short.

Now, does anyone know an typical turn ratio for these devices (or an
output voltage)? Anything i can work with to make a good guess of the
original will be appreciated.

A datasheet for the MP1015 can be found athttp://www.datasheet4u.com/download.php?id=527185
, for those interested.

This thread might be of use re: dissolving transformer epoxy:
http://groups.google.com/group/sci....7c38f3d5c?lnk=gst&q=inverter+wal+mart&rnum=4#

If you go that route, be very careful. Boiling acetone is very
dangerous. (flammable, can asphyxiate you - displace oxygen that you
breathe.)

If available where you are, try dissolving it in 100% biodiesel. That
dissolves all sorts of stuff - rubber, etc. (methyl linoleate is one
component of biodiesel, IIRC)

Michael

 

[[email protected]]

I wasn't planning to recycle the core - the idea was to replace it
altogheter (there's plenty of room in the laptop housing for a slighty
larger, stock one). The epoxing got in the way of removing the
original secondary, and at this point there's little of the original
device left to work with.

Anyway, the transformer is divided in 5 sections (see
http://lisandro.homelinux.org/ccfl_inverter.jpg ) - i managed to count
about 230 turns on one, so i'm guessing 250 turns per section, which
gives a 50:1 turns ratio (25 pri, 1250 sec). I'm wondering if this is
more or less correct for these devices.

 

[Jeff L]

I wasn't planning to recycle the core - the idea was to replace it
altogheter (there's plenty of room in the laptop housing for a slighty
larger, stock one). The epoxing got in the way of removing the
original secondary, and at this point there's little of the original
device left to work with.

Anyway, the transformer is divided in 5 sections (see
http://lisandro.homelinux.org/ccfl_inverter.jpg ) - i managed to count
about 230 turns on one, so i'm guessing 250 turns per section, which
gives a 50:1 turns ratio (25 pri, 1250 sec). I'm wondering if this is
more or less correct for these devices.

Go to Digikey.com and type in "TRANSFORMER CCFL" in the serch box. You may
find something that may fit

 

[[email protected]]

Go to Digikey.com and type in "TRANSFORMER CCFL" in the serch box. You may
find something that may fit

Just did - also found some Maxim application notes on selecting output
transformers for CCFL. Apparently 1:50 - 1:70 is about right for these
devices, and it's preferible to have more windings in the secondary
than less (the driver circuit can compensate for the winding
difference but with less stress for the first case).

 

[Eeyore]

Go to Digikey.com and type in "TRANSFORMER CCFL" in the serch box. You may
find something that may fit

Or go to ebay and type "backlight inverter".

Graham