Over the last couple of weeks my Iiyama 21" Vision Master (MT-9021)
monitor's started making a series of sharp crackles when being turned
on or off, and occasionally it's completely lost picture for a fraction of
a second (also accompanied by a loud crack).

Certainly sounds like something's arcing where it shouldn't be - I'm
pretty sure the noise isn't coming from any of the relays. There's no
visible arc though in a dark room with the case off when the screen's
turned on or off.

Internal short in the flyback? Any common failure points in these
particular displays related to these sorts of symptoms?

The display seems to be having voltage regulation trouble too - there
seems to be quite a bit of 'bounce' when changing from a dark to light
screen. Unfortunately I can't be certain that it wasn't there before these
HV troubles started.

No sign of bulging / leaking caps, but I haven't got to the point of doing
any real tests yet - thought I'd ask group wisdom first!

cheers

Jules