HP Laptop PSU

[Radio Fixer]

Why does the power supply need a mains earth?

Seems to me possibly for interference suppression components.

Came up as the unit trips out the earth leakage breaker.  It appears to be just the lead (odd) at 7K5 from line to earth but who know the unit may have caused the fault.  However a new lead is  £3.50 and lead with PSU replacement £9.50 so its the better deal.

Being as my wife's 'charging station' is in the utility room its a problem as the fridge and freezer are on the same breaker.  Cant easily do anything about that so thinking of a socket strip run from an isolation transformer and still can run the earth through.

Any comments welcome

thanks Gary

[Mark Hennessy]

Is that a genuine HP PSU at that price?

The problem has only arisen because of a fault; ordinarily, the leakage of a good PSU will be less than a milliamp. So, I wouldn't bother with isolation transformers, etc. In effect, the RCD has alerted you to a fault that could have got worse - perhaps with serious consequences - if masked by an isolation TX.

Yes, interference reasons mostly. Some laptop PSUs are class 2, but that means the chassis of the laptop ends up floating at half-mains because of leakage capacitance and interference suppression capacitors. Not usually a problem because of the very high source impedance, but it did catch one of our presenters out many years ago (long story that I've told several times before).

[Refugee]

I would simply replace the capacitors in the filter area on the PCB.
It there was no safety device present the capacitors would have melted and made a lot of smoke.

[Mark Hennessy]

Didn't Gary say it was the lead, not the PSU? Presumably some sort of breakdown of the insulation - pretty rare, but anything is possible... The usual cause is pets IME

They are usually "cloverleaf" C5 types on HP PSUs. Not quite as ubiquitous as the standard C13, but getting there...

Having had a quick search, genuine HP units are a little more than £9.50, but not so much more as to make it unrealistic (around £30, depending on model). There's no shortage of websites and videos explaining why cheap generic PSUs are best avoided. If you do get a cheapie, check that mains earth is carried through to the laptop chassis and definitely keep the RCD functional

[Radio Fixer]

http://www.ebay.co.uk/itm/For-HP-Pavilio...xydlFS4656

Scroll down for blurb.

Yes! its the lead that measures 7K5 and gets warm. Not done by pets as have none and its in a cupboard.

I don't want the RCD to alert me to a problem that may get worse, although fire would be pretty bad. Its cutting out the supply to fridge and freezer if out for the day that's worrying. Always turn all that stuff off when on holiday. Perhaps the 'charging station has to move to another location on a different RCD, could be best.

thanks Gary

[Radio Fixer]

Cancelled the order on the Ebay one and will get a genuine HP. Daft of me to even consider anything else.

Gary

[Nick]

Cancelled the order on the Ebay one and will get a genuine HP.   Daft of me to even consider anything else.

Phew! Good man...

[Mark Hennessy]

Phew! Good man...

Seconded

[Terry]

My previous Toshiba laptop had a 3-pin socket but the current machine - essentially the same but with improved processor, etc. has a 2-pin lead!

For all practical purposes, both PSUs are identical. In fact, I keep the original 3-pin one for permanent use at home and  the newer 2 - pin one resides in the laptop bag for when I go anywhere else.

A significant advantage of the 2-pin plug is that I have a figure or eight lead fitted with a moulded 6A 2-pin European plug which takes up a fraction of the space occupied by its predecessor clover leaf to Schuko one!

I also have a decent, well made Shuko adaptor which takes up little more space than a  13A plug, so I don't even need a second lead!