While looking for the correct pronunciation of 站 (zhàn / zhan4), I've come across several different recordings in online dictionaries, Forvo, wiktionary, and Google Translate, for example.
Sometimes it's pronounced as "dshan" (the "a" like in "angry" or the German umlaut "ä" / IPA -æn) and sometimes as "dshuhn" (like "un" / IPA -ʌn).
Is this a regional difference? What is the "standard pronunciation" as you would expect to hear it in TV news etc. in mainland China?