Rodney Pont wrote:
Thanks for the suggestion Simoc.

You're welcome.

I had thought of caps but if it's been on 24 hours previously it only
takes 2 seconds before powering up yet if it's been a week it takes 2
minutes. Can you see a cap in the power supply not fully discharging in
24 hours? Then there is the ten years I've had the printer and it's
occasionally gone a couple of weeks between being used, surely the caps
would have discharged in that time and I would have seen the same
problem.

Bad caps cause exactly that kind of behavior. You just have missed some
of the theory, I explain:

You are probably thinking, that the 2 mins would be normal when they're
discharged. But not, that's not the point. If the caps were good, they
would charge virtually immediately when powered, even if they're fully
discharged. That explained your last sentence (as then the caps weren't
dried out yet).

But as they are now dried out due to aging, their ESRs have increased
and that reduces both the charge and discharge current, causing too
much ripple voltage (and thus preventing the device from working). They
probably get discharged within 24h, but the point is there, that those
caps get _temporarily_ "rejuvenated" (ESRs decrease) when power is
applied for long enough time (the 2 min), by causing them to heat up.
But once the device is turned off, the caps cool down and then the
"rejuvenation" begins to lose its effect (ESRs begin to increase again)
_slowly_ (not immediately when cooled down and discharged, but within a
few days).

So the dried out caps should be replaced with new ones. Easy repair :-)

I was thinking more along the lines of a battery to be honest, maybe on
the processor board.

What battery? If there is one (I'm doubting), it's for memory back-up
and if bad, it would cause the device not to remember settings when
disconnected, but it doesn't cause the delayed start-up.

There isn't any obvious damage to the psu and no
caps are leaking or bulging.

Bad caps don't bulge nor leak in most cases (although sometimes do).

--
Top-posting not supported.