110v ac switching PS conversion to 220v

[Fernando Cassia]

Hi,

Anyone got any pointers for the conversion of a switching power supply
designed for 110v to 220v?.

The PS uses a Fairchild Semi IC (5M02659R).

Would it be too difficult to turn this PS into one taking 220v as
source?.

Thanks in advance

FC

 

[petrus bitbyter]

"Fernando Cassia" <fcassia@gmail.com> schreef in bericht
news:52733fad.0411090522.6d3fb59e@posting.google.com...

Hi,

Anyone got any pointers for the conversion of a switching power supply
designed for 110v to 220v?.

The PS uses a Fairchild Semi IC (5M02659R).

Would it be too difficult to turn this PS into one taking 220v as
source?.

Thanks in advance

FC

The IC has little to do with your question. You have to look at the way the
mains is rectified, so the DC voltage that powers the IC. If that voltage is
below 200VDC you have bad luck. It means that the transformer has been made
for that voltage and modifiing it will be hardly possible. On the other
hand, if the voltage is above 300VDC, the mains rectifier uses a voltage
doubler. See a more or less standard mains rectifier schematic below. If you
are very lucky you'll find a bridge rectifier and you'll only have to look
for the switch. Which may not be a real switch but only a piece of wire.
Otherwise you'll have to replace two mains rectifier diodes by a mains
bridge rectifier *and* disconnect the mains wire from capacitors.

+----+-----------+-------
| | |
- - ---
^ ^ ---
| | |
| | , |
------------+ +--+-o´ o---+
| | | switch |
mains | | | |
- - | ---
220Vac switch open ^ ^ | ---
| | | |
110Vac switch closed| | | |
+----+--|--------+-------
|
--------------------+
(created by AACircuit v1.28 beta 10/06/04 www.tech-chat.de)

petrus bitbyter



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[CWatters]

"petrus bitbyter" <p.kralt@reducespamforchello.nl> wrote in message
news:JG8kd.8535$kT6.5167@amsnews02.chello.com...

Otherwise you'll have to replace two mains rectifier diodes by a mains
bridge rectifier *and* disconnect the mains wire from capacitors.

If it's a wire link then check the voltage rating on those caps as well.

 

[Art]

Another way to accomplish this is to use a step down transformer commonly
used when traveling from one location to another. S.A. going from US to
Europe, etc.
"CWatters" <colin.watters@pandoraBOX.be> wrote in message
news:MLjkd.17524$5A7.1167495@phobos.telenet-ops.be...

"petrus bitbyter" <p.kralt@reducespamforchello.nl> wrote in message
news:JG8kd.8535$kT6.5167@amsnews02.chello.com...

Otherwise you'll have to replace two mains rectifier diodes by a mains
bridge rectifier *and* disconnect the mains wire from capacitors.

If it's a wire link then check the voltage rating on those caps as well.

 

[CWatters]

"Art" <plotsligt@comcast.net> wrote in message
news:i_idnfMMjp552Q7cRVn-1w@comcast.com...

Another way to accomplish this is to use a step down transformer commonly
used when traveling from one location to another. S.A. going from US to

They work well. Just be sure to get one designed for the power you need.
Many of those sold at airports are small low power devices only suitable for
mobile phones etc. If you need 400W to power a big PC then you may have to
hunt around a bit.

 

[Fernando Cassia]

"CWatters" <colin.watters@pandoraBOX.be> wrote in message news:<WW2ld.20208$KS.971887@phobos.telenet-ops.be>...

"Art" <plotsligt@comcast.net> wrote in message
news:i_idnfMMjp552Q7cRVn-1w@comcast.com...
Another way to accomplish this is to use a step down transformer commonly
used when traveling from one location to another. S.A. going from US to

They work well. Just be sure to get one designed for the power you need.
Many of those sold at airports are small low power devices only suitable for
mobile phones etc. If you need 400W to power a big PC then you may have to
hunt around a bit.

I originally asked the question of the switching PS modification
specifically to avoid having to add a bulky external step-down
transformer. Even the small ones are an annoyance.

FC

 

[John G]

"Fernando Cassia" <fcassia@gmail.com> wrote in message
news:52733fad.0411182146.1841fbff@posting.google.com...

"CWatters" <colin.watters@pandoraBOX.be> wrote in message
news:<WW2ld.20208$KS.971887@phobos.telenet-ops.be>...
"Art" <plotsligt@comcast.net> wrote in message
news:i_idnfMMjp552Q7cRVn-1w@comcast.com...
Another way to accomplish this is to use a step down transformer
commonly
used when traveling from one location to another. S.A. going from
US to

They work well. Just be sure to get one designed for the power you
need.
Many of those sold at airports are small low power devices only
suitable for
mobile phones etc. If you need 400W to power a big PC then you may
have to
hunt around a bit.

I originally asked the question of the switching PS modification
specifically to avoid having to add a bulky external step-down
transformer. Even the small ones are an annoyance.

FC

Most of the above is questionable advice.

The lightweight "transformers" often sold at airports are only diodes
or SCRs that chop half the supply and are hence not too good for
anything other than heating devices.

Changing anything within the power supply will void the HIPOT test done
by the manufacturer and thereby void the UL/CSA or whatever approval was
appropriate.

Then a fire or electrocution would be on your head.

--
John G

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