Correct wattage - step down transformer for SONY Vaio in Malaysia

[BLG]

Hello,

I'm in KL, Malaysia for the next several months and brought my SONY
Vaio (RX672) with me. I've blown the fuse in two step down
transformers (one 85 watt and one 100 watt) and wonder now how big a
transformer I need. The specs for the SONY are: AC INPUT 100-120V
~3.9A. This machine DOES NOT have a dual power supply switch and the
system guide specifically says "Your computer operates on 100-120 V AC
50/60Hz only." Which means, I need a transformer but I can't decide
how big to go.

Any one out there with experience to point me to the appropriate
transformer? Also, I'll be powering an HP Laser Jet 2100 which
probably means I'll also need a 500 Watt transformer for that device
as well. Any input on that matter will also be appreciated.

Thanks for all in advance for your replies,
Bennie Gibson

[Charles Howse]

Previously BLG <benniegibson@mindspring.com> wrote: Hello,
I'm in KL, Malaysia for the next several months and brought my SONY Vaio (RX672) with me. I've blown the fuse in two step down transformers (one 85 watt and one 100 watt) and wonder now how big a transformer I need. The specs for the SONY are: AC INPUT 100-120V ~3.9A. This machine DOES NOT have a dual power supply switch and the system guide specifically says "Your computer operates on 100-120 V AC 50/60Hz only." Which means, I need a transformer but I can't decide how big to go.

120V at 3.9 A is 468.0 W. Of course that is worst-case and
will only happen at power up for some miliseconds or so. Still it
is enought to blow a fuse under some conditions, which is also the
reason it is stated on the PSU.

A better figure for an operating upper limit can be gotten when taking
the output power (on my SR11K that is 16V/4A = 64W) and multiplying by
about 1.5 for losses (66% efficiency is a rather low estimate), which
gives 96W. If the output power of your PSU is in that range, what you
need is a step-down transformer with a permanent load rating >= 100W
and a peak load rating of >=470W.

The transformers I have seen (not many) have only about 180% of the
permanent maximum load as peak rating. That means you might have
to get soemthing in the >= 250W range.

The 3.9A rating is rather high. My PSU has a 1.1A rating at 100V.
It might be cheaper to get a 230V PSU for your Laptop, probably
not from Sony.
Any one out there with experience to point me to the appropriate transformer? Also, I'll be powering an HP Laser Jet 2100 which probably means I'll also need a 500 Watt transformer for that device as well. Any input on that matter will also be appreciated.

HP recomends 5A "circuit capacity" for this printer. Translates
to about 600W peak load, which translates to >=350W permanent rating
and >=600W peak rating for the transformer. It might be cheaper to get
a new printer for the duration of your stay. A good quality step-down
transformer for >= 350W is is about 200 swiss francs here. A Brother
HL-1430 is only 60 swiss francs more.

One other thing you can try is geting one single 500/600W step-down
converter. If you do not switch on both devices at once, it has to
tilerate just the peak current from one device.

Arno
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