XML Parsing - PHP encoding

I have a big XML (>15Mb) and i have to read it, parse it, and store some values in a DB. My problem is, the XML's come in in differents formats (UTF-8, ISO-8859-1).

With UTF-8 no prob. But ISO-8859-1 is giving me huge problems!! The tags come with special charachters which are not parsed correctly by XMLReader and readOuterXML()

Tryed already with, but with no luck

$xml = new XMLReader;
$xml->open($import_file,'ISO-8859-1');  

Tried with:

• utf8_encode


• mb_convert_encoding($stringXML, 'UTF-8' );


• iconv("ISO-8859-1", "UTF-8//TRANSLIT", $stringXML);

None of them helped me.