21 Sep
2005
21 Sep
'05
3:32 a.m.
No need for hd but need the HD rails, floppy drives and power supply.
I have the model 80 motherboard waiting for a case.
If someone wants the 220AC only PSU for industrial 80/60/65, feel
free to take it. PSU is a big restangular passive cooled with
screened cage cover.
I was advised that to change this 220VAC unit to 115VAC would
not work even I knew what exactly to do just install voltage doubler
circuit.
Cheers, Wizard
4:34 p.m.
On 9/21/2005, jpero at sympatico.ca wrote:
I was advised that to change this 220VAC unit to 115VAC
would
not work even I knew what exactly to do just install voltage doubler circuit.
I got the same story from an IBM marketing rep when I wanted to take an (original) US-use
PC to India to run on 220v 50Hz. He was right, but for a reason that I hadn't
considered.
In the old 60w PC power supplies, the fan is AC-operated and is specific to the line
voltage stamped on the nameplate. I simply replaced the fan with a DC-operated one (maybe
it taxed the meager +12 supply a bit, but hey, it worked) and bundled the unit off to
Bangalore where it put in several years of service.
I don't know if the same situation obtains for you, but you could also just keep the
box and substitute the innards from a generic PC power supply.
I was looking through the stuff in my garage and noted that I still have a carton of old
PS/2 Diskette Adapter/A (5.25") boxes. These were surplused by IBM and the drives
themselves scavenged for resale, but I've still got the cases complete with power
supply and cable and hardware (including the tamper-proof Torx screws) in their original
shipping boxes. They're really very well constructed units.
Anyone interested?
Cheers,
Chuck
8:01 p.m.
On 9/21/2005, jpero at sympatico.ca wrote:
Interesting...
The IBM PC and PC/XT power supplies that I've seen over here are, of course,
designed for 230V mains. I am pretty sure they're made by Zenith. From
what I remember, the fan is a 12V DC one but there is a mains-frequency
transformer with a 115V primary (!) connected between one side of the
mains and the centre-tap of the mains smoothing capacitors. A bit of
thought shows this is OK...
There is an internal link that converts the input rectifier to a voltage
doubler and in the process connects this transformer across the mains. In
other words it sets it for 115V.
The PortablePC is similar, but there's a user-accessible switch to set
the input voltage. It does much the same as the intenral link on the
other supplies.
-tony
I was advised that to change this 220VAC unit to
115VAC would
not work even I knew what exactly to do just install voltage doubler circuit.
I got the same story from an IBM marketing rep when I wanted to take
an (original) US-use PC to India to run on 220v 50Hz. He was right,
but for a reason that I hadn't considered.
In the old 60w PC power supplies, the fan is AC-operated and is
specific to the line voltage stamped on the nameplate. I simply
7:46 p.m.
I was advised that to change this 220VAC unit to
115VAC would
not work even I knew what exactly to do just install voltage doubler
circuit.
It's not unheard-of for SMPSUs to contain a mains-frequency transformer,
running off the AC mains, to provide the startup supply (or maybe all the
supplies for the control electronics). If that's the case, you do need to
do more than change the rectifier for a voltage doubler circuit to get
the right DC voltage across the mains smoothing capacitor
I would be _very_ suprised if this thing cared about mains frequency
(within sensible limits). I can see no reason why giving it 220V from a
step-up (auto)transformer wouldn't work.
-tony
9 p.m.
On Wed, 21 Sep 2005 07:32:03 +0000
jpero at sympatico.ca wrote:
No need for hd but need the HD rails, floppy drives
and power supply.
I have the model 80 motherboard waiting for a case.
If someone wants the 220AC only PSU for industrial 80/60/65, feel
free to take it. PSU is a big restangular passive cooled with
screened cage cover.
I was advised that to change this 220VAC unit to 115VAC would
not work even I knew what exactly to do just install voltage doubler
circuit.
Cheers, Wizard
A crude method is to find three biggish AC power transformers all the
same. Hook all three secondaries together in parallel, then use one of
the primaries as the primary and hook the other two secondaries
series-aiding to make the 220 volt 'secondary.' Doesn't even matter
that much what the secondary voltage of each transformer is, as long as
they're identical. A crude, big, heavy, lossy solution, but workable
esp. since it's not that hard to find three matching 'boat anchor'
transformers at some surplus outfit.
9:53 p.m.
A crude method is to find three biggish AC power
transformers all the
same. Hook all three secondaries together in parallel, then use one
of the primaries as the primary and hook the other two secondaries
series-aiding to make the 220 volt 'secondary.'
Just watch your phasing; get the leads swapped to one of the "other
two" transformers and you'll get (nominal) zero voltage instead of
double voltage.
Indeed, you can do something autotransformerish with only two
transformers:
---------------------.
IN |
--------+------------|-------------------------------
| +----+ OUT
| | | +-------------
| | | |
|_()()()()()_| |_()()()()()_|
_==========_ _==========_
| ()()()()() | | ()()()()() |
| | | |
+------------|----+ |
+-----------------+
Of course, the three-transformer version produces double voltage that's
isolated from the input, whereas the above doesn't. Also, you still
have to watch the phasing; get a winding's leads swapped and you get
zero voltage instead of doubled voltage.
/~\ The ASCII der Mouse
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22 Sep
22 Sep
3:57 a.m.
On 9/21/2005, der Mouse wrote:
Indeed, you can do something autotransformerish with
only two
transformers:
---------------------.
IN |
--------+------------|-------------------------------
| +----+ OUT
| | | +-------------
| | | |
|_()()()()()_| |_()()()()()_|
========================
...or just one, if you can find a "universal" 120/240 volt transformer of
sufficient VA rating (the secondary is NC, so the secondary voltage doesn't matter).
I'm not as artistic, so I'll borrow the artwork and just add a couple of lines.
The "split bobbin" types are fairly common, even in 220 vac countries, as it
lets a manufacturer change the nameplate voltage of a linear power supply with just a
change of jumper and fuse.
6873
days inactive
6874
days old
7 comments
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participants (6)
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ard＠p850ug1.demon.co.uk -
cclist＠sydex.com -
chenmel＠earthlink.net -
jpero＠sympatico.ca -
mouse＠Rodents.Montreal.QC.CA -
nico＠FARUMDATA.DK