Risc PC power supply---how powerful?
Dick Smith
I have an early Risc PC with a MK1 motherboard and all the power supply leads
are in use powering floppy, hard and CD ROM drives; one of each.
I have the chance to lash up a second HD and am wondering if splitting a
power supply lead to feed the extra HD would prove too much for the power
supply. Does anyone know if the power supply would handle an extra HD OK?
Thanks for any information.
Dick
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=============================================================================
Dick Smith Acorn Risc PC di...@risctex.demon.co.uk
=============================================================================
Stuart Bell
In article <19980328....@risctex.demon.co.uk>,
Dick Smith <di...@risctex.demon.co.uk> wrote:
> I have an early Risc PC with a MK1 motherboard and all the power supply
leads
> are in use powering floppy, hard and CD ROM drives; one of each.
> I have the chance to lash up a second HD and am wondering if splitting a
> power supply lead to feed the extra HD would prove too much for the power
> supply. Does anyone know if the power supply would handle an extra HD
OK?
IMHO, and limited experience, adding one extra HD with a spiltter
shouldn't prove fatal to the PSU. If they go, they go in any case, and
many have gone without excessive loading.
At your own risk, of course. . . . .
--
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Running an Acorn Risc PC, a Mac Color Classic and
an Apple PowerBook 100 in a Wintel-free Zone.
Patrick Bean
In article <19980328....@risctex.demon.co.uk>,
di...@risctex.demon.co.uk (Dick Smith) wrote:
> I have an early Risc PC with a MK1 motherboard and all the power supply
> leads
> are in use powering floppy, hard and CD ROM drives; one of each.
The power supplies on a Mk 1 motherboards were 70 watt, if you have a second
slice you will have got an upgraded one with it, that will be a 105 watt I
think.
> I have the chance to lash up a second HD and am wondering if splitting a
> power supply lead to feed the extra HD would prove too much for the power
> supply. Does anyone know if the power supply would handle an extra HD OK?
I have a 586 PC card that came with a power splitter to drive the fan. I
take it that they would not give you the splitter it you could not have a
Hard disk, CD-ROM and the 586 fan. If you have a 105 watt supply then you
should have no problem at all.
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Rialto
In article <19980328....@risctex.demon.co.uk>,
di...@risctex.demon.co.uk (Dick Smith) wrote:
>
> I have an early Risc PC with a MK1 motherboard and all the power supply
> leads are in use powering floppy, hard and CD ROM drives; one of each.
> power supply lead to feed the extra HD would prove too much for the power
> supply. Does anyone know if the power supply would handle an extra HD OK?
hard/cdrom drives and one small plug for the floppy. If it is the RPC600, I
don't know. BUT the power supply will say on the label what the maximum
load is. The earlier supplies for two slice models could belt out 103 watts
which was ample for fully occupied leads. The power supply will also say
what it can supply at each voltage. Each drive is marked with its needs,
and it is just a matter of adding up.
In practice, there should be no problem at all in supplying an extra drive,
especially if all the leads are not used. The last spare is often tucked
away under the bottom slice to the front and is not readily visible.
My last word, I had three hard drives and a cdrom drive running off my 103
watt supply with no signs of distress.
Kenneth
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Jim Lesurf
In article <na.83458c482e....@argonet.co.uk>,
Rialto <munn...@argonet.co.uk> wrote:
> In article <19980328....@risctex.demon.co.uk>,
> di...@risctex.demon.co.uk (Dick Smith) wrote:
> >
> > I have an early Risc PC with a MK1 motherboard and all the power
> > supply leads are in use powering floppy, hard and CD ROM drives; one
> > of each. I have the chance to lash up a second HD and am wondering if
> > splitting a power supply lead to feed the extra HD would prove too
> > much for the power supply. Does anyone know if the power supply would
> > handle an extra HD OK?
> Strange! If it is a Risc PC700, there should be four standard size plugs
> for hard/cdrom drives and one small plug for the floppy. If it is the
> RPC600, I don't know.
That's for a two-slice 103W supply version, I think.
My home machine was 1-slice 70W supply. A Shottky diode in these is prone
to failing. However this doesn't seem to depend much upon adding another
drive. I get the impression that they *all* fail eventually... Later
machines have the 103W supply as standard, I think.
I'd say, "go for it!". Either way, if the diode blows sometime, replace it
with a better part[1] or get the 103W supply. :-)
Slainte,
Jim
[1] If you want the part number, etc, I'm sure Pat will be along in a mo'
to tell you. :-)
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Stuart Bell
In article <na.83458c482e....@argonet.co.uk>,
Rialto <munn...@argonet.co.uk> wrote:
> In article <19980328....@risctex.demon.co.uk>,
> di...@risctex.demon.co.uk (Dick Smith) wrote:
> >
> > I have an early Risc PC with a MK1 motherboard and all the power
> > supply leads are in use powering floppy, hard and CD ROM drives; one
> > of each. I have the chance to lash up a second HD and am wondering if
> > splitting a power supply lead to feed the extra HD would prove too
> > much for the power supply. Does anyone know if the power supply would
> > handle an extra HD OK?
> Strange! If it is a Risc PC700, there should be four standard size plugs
> for hard/cdrom drives and one small plug for the floppy. If it is the
> RPC600, I don't know.
'Fraid it's not as simple as that. Some RPC700s only had the earlier type
70W supply; the move to 103W was much later than the arrival of the RPC700.
It's a matter of reading the label! ;-)
Dave Cooper
In article <19980328....@risctex.demon.co.uk>,
di...@risctex.demon.co.uk (Dick Smith) wrote:
>
> I have an early Risc PC with a MK1 motherboard and all the power supply
> leads
> are in use powering floppy, hard and CD ROM drives; one of each.
>
> I have the chance to lash up a second HD and am wondering if splitting a
> power supply lead to feed the extra HD would prove too much for the power
> supply. Does anyone know if the power supply would handle an extra HD OK?
>
>
> Dick
>
the monitor. With my system -an early single slice 600 upgraded to StrongARM
-I have the monitor (AlphaScan) plugged into the mains separately.
Surely people not drawing power for the monitor would be able to power up an
extra harddisc?
Regards, Dave C.
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John Williams
In article <na.918f5b48...@argonet.co.uk>,
Dave Cooper <d...@argonet.co.uk> wrote:
> Surely people not drawing power for the monitor would be able to power
> up an extra harddisc?
I fear that the outlet for the monitor is merely a switched mains socket
for convenience, and thus has no bearing whatsoever on the power supply
other than being connected to the same mains plug.
It's a bit like saying "The family next door have gone to bed now so I can
power up my hard drive more safely!"
'Nuff said.
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jAmES Lawson
di...@risctex.demon.co.uk (Dick Smith) wrote:
> I have the chance to lash up a second HD and am wondering if splitting a
> power supply lead to feed the extra HD would prove too much for the power
> supply. Does anyone know if the power supply would handle an extra HD OK?
I killed the original 70W PSU on my RPC600 when I replaced the CD
with a second hard disk.
Bought a reconditioned 105W from Acorn for just under £50 if I
remember correctly.
jAmES
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David Lomas
Dick Smith wrote:
>
> I have an early Risc PC with a MK1 motherboard and all the power supply leads
> are in use powering floppy, hard and CD ROM drives; one of each.
>
> power supply lead to feed the extra HD would prove too much for the power
> supply. Does anyone know if the power supply would handle an extra HD OK?
>
>
> Dick
Having recently received information about my dead RPC600 power supply
(in terms of what components are likely to have died), I found that to
replace all the dead things (2 or 3 more diodes gone short circuit)
would come to about 10 quid. A 200W PC power supply, boxed, can be had
for about 15 quid, so I think I know what I'm going to do.
Run a 5 or 6 way low voltage cable from the new PSU to the RPC. Take the
old circuit out of the RPC PSU, but retain the metal case and fan. Mount
a suitable low voltage connector on the back in place of the IEC mains
connectors. You then probably have room for another disc drive _inside_
what was once the PSU.
The only down side I can see is that there is an extra box to put on the
desk, and the main power switch is now not on the machine unit, but on
the power supply box.
Cheers,
Dave.
Patrick Herborn
In message <482e58e...@st-and.demon.co.uk>
Jim Lesurf <jc...@st-and.demon.co.uk> wrote:
> I'd say, "go for it!". Either way, if the diode blows sometime, replace it
> with a better part[1] or get the 103W supply. :-)
Yes, I'de go along with that. I have had, at times, in my machine two HDDs,
one CDROM, 64MB DRAM, SA, 486, Ethernet card, SCSI card and floppy. All this
runs off the standard 70W supply!
> [1] If you want the part number, etc, I'm sure Pat will be along in a mo'
> to tell you. :-)
The part is an MBR2045CT. I replaced two of mine with STPS2045CT. They have
not failed yet... <fx:touches wood>
Cheers,
Pat.
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Kira L. Brown
In message <na.311d53482e...@argonet.co.uk>
Patrick Bean <pdb...@argonet.co.uk> wrote:
> I have a 586 PC card that came with a power splitter to drive the fan. I
A second hard drive uses a wee bit more power than a fan does.
kira.
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Mik Towse
In article <482F08AF7E%kbr...@cgram.demon.com.uk>,
Kira L. Brown <kbr...@cgram.demon.com.uk> wrote:
> In message <na.311d53482e...@argonet.co.uk>
> Patrick Bean <pdb...@argonet.co.uk> wrote:
> > I have a 586 PC card that came with a power splitter to drive the
> > fan.
> A second hard drive uses a wee bit more power than a fan does.
But it'll be close for a Pentium II fan.;o}
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This tagline is proud to have been written on an ACORN computer
Kira L. Brown
In message <na.918f5b48...@argonet.co.uk>
Dave Cooper <d...@argonet.co.uk> wrote:
> In article <19980328....@risctex.demon.co.uk>,
> di...@risctex.demon.co.uk (Dick Smith) wrote:
> >
> > I have an early Risc PC with a MK1 motherboard and all the power supply
> > leads
> > are in use powering floppy, hard and CD ROM drives; one of each.
> >
> > I have the chance to lash up a second HD and am wondering if splitting a
> > power supply lead to feed the extra HD would prove too much for the power
> > supply. Does anyone know if the power supply would handle an extra HD OK?
> >
> > Thanks for any information.
> >
> > Dick
> >
> As a related question - at the back of the Risc Pc is a power socket for
> the monitor. With my system -an early single slice 600 upgraded to StrongARM
> -I have the monitor (AlphaScan) plugged into the mains separately.
>
> Surely people not drawing power for the monitor would be able to power up an
> extra harddisc?
No.
The power for the monitor never goes through the actual PSU, merely
through the switch.
The PSU itself is the bit where mains power is converted into the smooth,
clean, rectified, low voltages required for digital electronics.
The monitor, however, requires whopping great voltages, and so needs
to draw power straight from the mains. Which it does, through the
passthrough socket. Think of it as a piggyback plug.
kira.
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Kira L. Brown. Testing Zap 1.39. Brave or what?
Worse things happen in C.
Mark Greenwood
Patrick Herborn wrote:
> Yes, I'de go along with that. I have had, at times, in my machine two HDDs,
> one CDROM, 64MB DRAM, SA, 486, Ethernet card, SCSI card and floppy. All this
> runs off the standard 70W supply!
>
Does anyone fancy hazarding a guess as to whether I'd get away with the
following off one power supply?
4 x HDDs (1 gig each)
1 x CD-ROM
1 x CD-Writer
1 x Floppy
SA
586
SCSI card
Sampler / MIDI
24 MB RAM + 2 MB VRAM?
I'm currently getting away with it except for the CD-writer and 8MB of
the RAM, but I've never tried leaving it on all day, as will sometimes
be necessary in the future. Anyone like to guess?
--
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A bollard on the information superhighway
micm
In article <482F12544B%kbr...@cgram.demon.com.uk>, Kira L. Brown
You need to watch how much power your monitor uses. On my RiscPC (which
has the larger PSU in it) the monitor is only rated at just over 1A
IIRC. My old monitor (A 15" Wyse) drew 1A exactly and was alright to
put on the passthrough. My new monitor (a nice Sony trinitron thing)
draws 1.8A. I have decided not to plug this into the back of the RiscPC
due to the fact that I know someone who blew their PSU up by plugging a
21"er into the back of their PC, which had much the same power supply,
also rated at 1A.......
So be careful what you plug into that socket.
[ Q'98 ] [ micm ]
[ Quote Wot U Want ]
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David Leftley
On Tue, 31 Mar 1998 19:47:40 +0100, micm
<your.pa...@enterprise.net> wrote:
>You need to watch how much power your monitor uses. On my RiscPC (which
>has the larger PSU in it) the monitor is only rated at just over 1A
>IIRC. My old monitor (A 15" Wyse) drew 1A exactly and was alright to
>put on the passthrough. My new monitor (a nice Sony trinitron thing)
>draws 1.8A. I have decided not to plug this into the back of the RiscPC
>due to the fact that I know someone who blew their PSU up by plugging a
>21"er into the back of their PC, which had much the same power supply,
>also rated at 1A.......
So which component is likely to blow up when a higher-rated monitor is
plugged in? It can't be the PSU itself, since as Kira said earlier,
the power to the monitor doesn't actually come from the PSU. Is it the
switch?
BTW, I've been using a monitor that claims to be rated at 1.8A on my
A5000 for 3.5 years now without anything going wrong, and my PSU is
also powering a couple of expansion cards, a second hard drive and an
external CD-ROM.
David.
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Posting from work, but all views are my own.
Ian Molton
In article <352260c9....@news.rmplc.co.uk>,
David Leftley <dav...@rcp.co.uk> wrote:
> So which component is likely to blow up when a higher-rated monitor is
> plugged in? It can't be the PSU itself, since as Kira said earlier,
> the power to the monitor doesn't actually come from the PSU. Is it the
> switch?
Umm. socket? wiring between switch and socket, switch itself, fuse in mains
plug?
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Rialto
In article <352260c9....@news.rmplc.co.uk>, dav...@rcp.co.uk (David
Leftley) wrote:
> So which component is likely to blow up when a higher-rated monitor is
> plugged in? It can't be the PSU itself, since as Kira said earlier,
> the power to the monitor doesn't actually come from the PSU. Is it the
> switch
If anything is blown, it will be the switch, as the monitor supply comes out
at mains potential. If you are in doubt, get a standard euro style lead to
go straight from the mains to the monitor.
I have all my computing stuff supplied through a single mains switch mounted
on my computer desk and it is this that I use to switch everything off
together. If this blows, it will be much easier and cheaper to replace.
Ken
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In message <352260c9....@news.rmplc.co.uk>, David Leftley
(dav...@rcp.co.uk) wrote:
>So which component is likely to blow up when a higher-rated monitor is
>plugged in? It can't be the PSU itself, since as Kira said earlier,
>the power to the monitor doesn't actually come from the PSU. Is it the
I'd worry that the mains switch would fail due to the switch-on surge
current. Wouldn't it be nice if the surge currents formed part of the ratings
shown on the outside of all equipment?
Dave
Anti-UCE address: davehigton at arcade dot demon period co period uk
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Kira L. Brown
In message <352260c9....@news.rmplc.co.uk>
dav...@rcp.co.uk (David Leftley) wrote:
> On Tue, 31 Mar 1998 19:47:40 +0100, micm
> <your.pa...@enterprise.net> wrote:
[snip]
> So which component is likely to blow up when a higher-rated monitor is
> plugged in? It can't be the PSU itself, since as Kira said earlier,
> the power to the monitor doesn't actually come from the PSU. Is it the
> switch?
Yes. But in extreme cases, the PCB tracks or interwiring might
fail.
You're usually okay though :-)
kira.
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Computer: a device designed to speed and automate errors.
Robin Clive-Matthews
In article <482F08AF7E%kbr...@cgram.demon.com.uk>, Kira L. Brown
<URL:mailto:kbr...@cgram.demon.com.uk> wrote:
> In message <na.311d53482e...@argonet.co.uk>
> Patrick Bean <pdb...@argonet.co.uk> wrote:
>
>
> A second hard drive uses a wee bit more power than a fan does.
I wonder how much the 5x86 uses when compared to a harddisc ...
I was reading the data sheet of some PC processor (either Pentium II or AMD K6)
and they needed about 12 amps at 5V ... :-)
BFN !
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Rialto
In article <980403...@arcade.demon.co.uk>,
address...@nospam.demon.co.uk (David Higton) wrote:
>
> I'd worry that the mains switch would fail due to the switch-on surge
> current. Wouldn't it be nice if the surge currents formed part of the
> ratings shown on the outside of all equipment?
They are implicit in the ratings. All manufacturers know about them. They
will not blow the switch within a reasonable lifetime, measured in years,
unless you have a bad or dirty switch. If in doubt, leave everything on and
use a sacrificial external switch of standard high current domestic design.
Paul Roegele
In article <3520B3...@madge.com>, Mark Greenwood <mgre...@madge.com>
wrote:
>
> Does anyone fancy hazarding a guess as to whether I'd get away with the
> following off one power supply?
>
> 4 x HDDs (1 gig each)
> 1 x CD-ROM
> 1 x CD-Writer
> 1 x Floppy
> SA
> 586
> SCSI card
> Sampler / MIDI
> 24 MB RAM + 2 MB VRAM?
>
Not entirely sure, but I regularly run...
1 x 32Meg SIMM
1 x 8Meg SIMM
1 x 1Meg VRAM
1 x 3.2 Gig HDD
1 x 540M HDD
1 x Floppy
1 x 8Speed CD ROM
Arm 719
486 SXL 33 (ssssslllllloooooooowwwww..)
Vidi Digitiser
Laser Direct Podule
A-Level Electronics Project - About 120mA
off my 70W supply without any problems.
Cheers,
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| (_||_|| | \(_)(/_(_|(/_|(/_ pa...@argonet.no.meat.4.me.co.uk
----------------------_|------- Posted on Sun,05 Apr at 19:50
Richard Sargeant
pa...@argonet.co.uk (Paul Roegele) wrote:
[list trimmed]
> A-Level Electronics Project - About 120mA
What did you create for this?
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Simon Burrows
Paul Roegele wrote:
> > Does anyone fancy hazarding a guess as to whether I'd get away with the
> > following off one power supply?
>
>
> off my 70W supply without any problems.
You mean without any problems _to date_.
I thought everything was fine until my PSU went up in
a puff of smoke, zapping most of the peripherals
connected to it. That was the higher rated PSU.
--
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I do not speak for Goldman Sachs
Patrick Herborn
In message <na.4e2802483...@argonet.co.uk>
Paul Roegele <pa...@argonet.co.uk> wrote:
> Not entirely sure, but I regularly run...
>
> 1 x 32Meg SIMM
2 x 32MB SIMMs
> 1 x 1Meg VRAM
Ditto.
> 1 x 3.2 Gig HDD
1 x 1.6GB Internal IDE. 1 x 9GB External SCSI
> 1 x 540M HDD
No extra internal HDD
> 1 x Floppy
1 x LS-120 Ultra High Density Floppy
> 1 x 8Speed CD ROM
1 x 12-20X PCAV SCSI CDROM
> Arm 719
SA-110 @ 202.4MHz
> 486 SXL 33 (ssssslllllloooooooowwwww..)
Ditto.
> Vidi Digitiser
Nope, but an Ethernet card.
> Laser Direct Podule
Pass, but a SCSI Podule
> A-Level Electronics Project - About 120mA
Pass, but a second fan :-)
> off my 70W supply without any problems.
Ditto. [External SCSI drive has own PSU, since it would overload the 70W PSU
if connected on it's own, never mind the rest of the RPC]
But pray do tell, how you have two HDDs and one CDROM without an IDE or SCSI
card ?
> Cheers,
Cheers,
Pat.
--
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| Patrick Herborn, | pat@nanobyte重emon縦o瞬k | Primary Mail Address |
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