1. Home
  2. Electronics Design
  3. Rewinding a laptop's CCFL driver transformer

Rewinding a laptop's CCFL driver transformer

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

formatting link
, for those interested.

Reply to
plisandro
Loading thread data ...

at

formatting link

This thread might be of use re: dissolving transformer epoxy:

formatting link

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

Reply to
mrdarrett

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

formatting link
) - 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.

Reply to
plisandro

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

Reply to
Jeff L

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).

Reply to
plisandro

ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.