Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: xaccrocheur on March 26, 2003, 07:51:30 AM
-
I bumped into another readme regarding the fitting of an old AT PSU to a 1200.
this link (http://onlyamiga.kicks-ass.net/main.xgi?page=a1200power)
My question is : If I use a 3.5' HD in (or out of) the 1200, how can I power the drive THRU the MoBo, to avoid an additionnal cable to be dangling from the side ?
since it HAS a power plug, unlike the 2.5 HDs... Where should I plug this latter power plug on the MoBo ?
Thank you
pX
-
You could splice the floppy power supply, which is what I did.
Be carefull! Normally, the amiga power connecter uses yellow as +5V and red as +12V whereas a PC molex connector is usually reversed, yellow is +12V and red is +5V. Grounds are always in the middle. You should look at the pinouts for a molex connector and verify the voltage on the Amiga side with a multimeter before striping soldering and insulating.
Other than this operation, I don't really know of an eaiser way.
-
Before getting a tower, I used an old PC supply.
I was worried about the current levels that would pass through the standard A1200 power socket, so I fitted an additional one.
I used a standard male hard disk power connector (from maplins), fitted into the back of my A1200, having cut a wee hole with a hacksaw and used a bit of super glue. I then powered the floppy disk/hard disk from this socket, and later added an additional feed to the mainboard via the original floppy power connector (be careful of the pin arrangement else you'll pump 12VDC into the 5VDC line!)
The upshot was that I had 2 power leads going into my A1200, both of which needed to be pugged in else it wouldn't work ;-)
This worked perfectly as a temporary fix until I got a tower.
-
Karlos wrote:
Before getting a tower, I used an old PC supply.
I was worried about the current levels that would pass through the standard A1200 power socket, so I fitted an additional one.
I used a standard male hard disk power connector (from maplins), fitted into the back of my A1200, having cut a wee hole with a hacksaw and used a bit of super glue. I then powered the floppy disk/hard disk from this socket, and later added an additional feed to the mainboard via the original floppy power connector (be careful of the pin arrangement else you'll pump 12VDC into the 5VDC line!)
The upshot was that I had 2 power leads going into my A1200, both of which needed to be pugged in else it wouldn't work ;-)
This worked perfectly as a temporary fix until I got a tower.
Sounds fine, that's what I envisioned in the 1st place. On the other hand GreggBz's solution is much more elegant : That way you only have 1 cable.
thanks for the options !
Now I'm wondering, this time on my 4000, can I plug *that* much items init ?
A4040 w/ orgiginal DaughterBoards
GVP HC+8 Ser.II Rev.II (has a PSU socket, drains it from the ZII port)
TEAC SCSI CD-ROM (x32 I guess)
Original HD FLoppy drive
Conner CP30540 (http://sunsolve.sun.com/handbook_pub/Devices/Disk/DISK_Cnnr_CP30540.html?wrapper=false) 520 Mg SCSI HD (came w/ the machine I guess, am I correct ?)
IBM DDRS-HG (http://sunsolve.sun.com/handbook_pub/Devices/Disk/DISK_IBM_DDRS_34560.html) 4560Mg SCSI HD
Seagate Hawk (http://www.seagate.com/cgi-bin/view.cgi?/scsi/st15230n.txt) ST15230N (the BIG one, server stuff, double the thickness and heavy metal case)
The two latter disks are not mounted yet, since I'm quite concerned about power issues. I don't want to be losing data by corruption or long stress-inducing revalidations...
pX
-
I've heard that one could feed extra power into the A1200 mobo by using the floppy connector.
Is this true? It sounds a little bit dangerous...
-
I'm running the standard 135 Watt PSU on my 3000 and have 4 Zorro
cards, 2 HDDs, 1 cd rom, HD FDD, CS060 plugged in with no ill effect
on the power. I have had 2 more HDDs and another cd and a cd-r
plugged into this system as well in the past, probably pushing the PSU
to the point I would not have added anything else :-) You should not
have a problem with your PSU.
-
miles wrote:
I'm running the standard 135 Watt PSU on my 3000 and have 4 Zorro
cards, 2 HDDs, 1 cd rom, HD FDD, CS060 plugged in with no ill effect
on the power. I have had 2 more HDDs and another cd and a cd-r
plugged into this system as well in the past, probably pushing the PSU
to the point I would not have added anything else :-) You should not
have a problem with your PSU.
Wow, indeed, that's reassuring. But then again, you have a 3K (lucky bastard) because my A4K's PSU reads "Output : 45W" witch is scary : I have a 250W PSU in one of my LinBoxes, is it really 3 times more powerful ? Or does the notation of those voltage are as serious as, say, the size of the monitors ? :-P
pX
-
whabang wrote:
I've heard that one could feed extra power into the A1200 mobo by using the floppy connector.
Is this true? It sounds a little bit dangerous...
Sure. I do that in my tower too. As long as your careful about not mixing up the lines.
In fact, if you have a greedy accelerator, ram, gfx card etc. (ie BlizzardPPC/BVisionPPC) its a must ;-)
-
xaccrocheur wrote:
Sounds fine, that's what I envisioned in the 1st place. On the other hand GreggBz's solution is much more elegant : That way you only have 1 cable.
thanks for the options !
Well, as I thought I said the point of having two cables was to alleviate the current levels flowing through the standard A1200 power socket - I didn't want to overload the regulators on there (which happened to an older mainboard of mine).
Better to be safe than sorry. Also, since I used a spare A1200 power cable (from an old PSU) it didnt look untidy, it was just another cable into the back of the machine.
-
So in theory, I could connect an AT PSU to the miggy via the floppy connector?
-
whabang wrote:
So in theory, I could connect an AT PSU to the miggy via the floppy connector?
You could, but I wouldnt reccomend it as a sole power feed. For example, you wouldn't get -12VDC in which case your sound would be screwed up and your serial port probably wont work properly. The 5VDC and 12VDC lines are the most loaded, esp 5V when you add a few extra tens of millions of transistors in the form of a bigger processor, more memory, gfx card, etc. etc.
If you want to jam the juice in, use both. Also (obviously) power all your drives / fans straight from the PSU.
-
@Karlos
Of course...
Thing is that the miggy hangs every now and then. The sound is corrupted etc. etc...
Conclusion: I don't think that ol PSU of mine is enought to power accelerator, HD, floppy, mobo...
-
whabang wrote:
@Karlos
Conclusion: I don't think that ol PSU of mine is enought to power accelerator, HD, floppy, mobo...
What do you have? It's not a standard C= PSU is it?
-
Yes it is... :) A bog standard A500 PSU. ( The machine won't even boot with the A1200 PSU :-P )
-
BTW. Do the different revisions of A1200 motherboards have a different power usage?
-
I assume you have gotten to the point where you have chopped the lead of the AT Power supply and connected to the A1200 connector.
Now once you have done that you can either:-
Splice the floppy connector to power the hardrive.
I would recommend this method as putting too much load on the floppy connector can lead to tracks burning out as they are very thin.
Take the motherboard out of the A1200 turn it over using a multimeter find out the voltage on the pads where the power connector is soldered.
For Hard Discs / CD-Roms you need +5v GND +12v
Cut one of the D-connects of your AT Power Supply with plenty of wire, as close as to the Power supply as possible.
Solder the Yellow (+12V) to the +12v Pad
Solder the Black (GND) to the GND Pad
Solder the Red (+5V) to the +12v Pad
Obviously verify the colours and voltages using the multimeter on the AT power supply first.
This way the load you require is not being drawn through the motherboard.
If you are feeling confident you can solder directly on the back of the Power Connector in the A1200.
-
Corrupt sound is usually a -12v problem
Middle Pin on the power connector, use a multimeter to see if -12V is coming out.
-
Just an aside: the 4000 PSU is 145W, not 45. I think the number '1' has been rubbed off yours.
I was always unhappy about the PSU in my 4000 - the fans used to slow down whenever the CD spun up. Now that it's in a tower with a proper ATX supply, I'm much happier.
tony
-
Can somebody confirm that the A4K PSU is only 45W, whereas for example, that of the 3K is 135W, and that of a basic PC is at least 200W...
That would place the A4K PSU just above "the brick", the tiny toyesque A1200 PSU...
Anyway I'm very concerned that it could not cope with the amount of W needed to fully operate my 3 big SCSI drives...
How can I make this sure ? the Electric specs are not even stated on one of the drives, the BIG Seagate HAWK (http://www.seagate.com/cgi-bin/view.cgi?/scsi/st15230n.txt)...
Well, if somebody has his 4000 as crowded as this, please drop me a line to reassure me ;-)
pX
-
Missing a "1" ?
145 W is perhaps nearer the right figure.
-
whabang wrote:
BTW. Do the different revisions of A1200 motherboards have a different power usage?
Possibly, but they all use the same voltages which is the important issue. The thing is, any piece of electrical hardware will only draw the power it requires irrespective of how much the PSU can deliver. It's when the hardware needs to draw more power (ie higher current) than the PSU can deliver that you get problems.
Basically you can end up getting voltage drops (so drawing too much current from the 5V line can pull the voltage down) so that the hardware becomes unreliable. Worse still, the PSU can burn out and take the hardware with it :-o
Anyway, bear in mind that the mainboard voltage regulators have a max current rating before they start to fry which is why I strongly advise a dual power input to the A1200 mainboard.
I know because this actually happened to me once when I had a dsektop 1200 using just the standard power connector with a 200W supply :-(
Luckily, I had an electrical engineer flat mate at the time who replaced the surface mount regs (in the lab at his workplace) so I got away with it ;-)
-
All wattage outputs quoted on power supplies is the MAXIMUM output not the continous sustainable output.
Cheers
Phoenix :-D
-
I never had Power problems in my 4000
(the only bad thing is the noisy fan)
I replaced it with silent one...
-
I cannot confirm the 4k has a 45 Watt PSU but I can say that a standard PSU for a PC is not a standard thing. I pulled a 130Watt PSU out of a Compaq POS with k6-2 400MHZ just the other day. I have seen old Dell computers with 65Watt PSU and i286. Now when you're talkin Athlon and P3 you wont see anything less than 250watt. but the newer Athlons and P4 will have 350 to 400 watt.
I don't understand what these guys are saying about "pumping" too much power into the mobo if the Wattage of the PSU is larger. What that says to me is that if you cross the 5 and 12 V you get more smoke.
Also, Hook the damn drive up to the Floppy connector and use a bigger PSU...
Problem solved