Amiga.org
Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: starf81 on June 01, 2005, 08:48:34 PM
-
Well... just solved the Apollo's issue, my "A1200 project" goes ahead. And, obviously, I've another problem :-D
Up to now, I've tested my configuration with an A500+ power supply but now I want to adapt an ATX one.
I had an old working 200W ATX power supply so I've adapted it using the original cable taken from the original A1200 PSU. I've found on the net some schematics to wire the ATX PSU to che Amiga cable: +12v, -12v, +5v and GND. After I've tested it with the A1200 and all work correctly.
But, as I attach the Apollo 1240, something goes wrong. The green power led is less strong, the screen is black and the fan wired to the Apollo's board turns slower.
I can't understand... I've tried two different ATX that work correctly with my PC. In addition, when I use the A500+ PSU, the Amiga and the Apollo work correctly.
Last note: to start the ATX PSU, I've linked the green "PS ON" cable with a black GND wire.
Could you help me? :-D
THANKS!
Alex
-
Is it just the 1240 card and no other expansions that this happens with?
A slower fan implies to me that there is a voltage drop on one of the rails. As far as I recall the fan on the Apollo1240 is a 12VDC one. You are definately sure the +12VDC line is correctly wired up?
-
Yes Karlos, only the 1240 and the mouse, no other devices or exansions.
I've taken the +12v line from the 4-wires molex as the +5v, while the -12v line comes from the 20 wires plug. Obviously I've tested them with a meter and are good.
In addition, as I said, I've tested two different ATX PSU, the old 200w and the 400w that I use everyday into my PC.
It's so strange... voltages are right and without the Apollo all work correctly. The Apollo works only with the A500 PSU.
Any ideas? :-?
Alex
-
Can you test the levels with the base A1200 and with the apollo attached? If possible chech the levels on the pins powering the fan and also on the floppy power header on the motherboard. If the fan is slower I'd expect the 12VDC line to be low.
I wonder if something is pulling too much current through some weak link?
-
Karlos wrote:
If the fan is slower I'd expect the 12VDC line to be low.
Or the ground could be high :-o
I'm scratching my head on this one, but since it all works with the a500 PSU I'd point to the re-wiring job.
Maybe something silly like the +/- 12v lines swapped, or a bad ground connection. Is the audio output distorted when using the ATX with no Apollo?
I was thinking about the +5v being low on the LED, but then remembered it only goes bright when after it's passed the startup checks in the ROM...which points to the CPU not working...which only confuses me more
:-x
-
You will need a AT Power unit ...
A ATX power unit will not work usually.
(power saving/stand by)
-
Tomorrow I'll measure voltages inside the Amiga. This is the only test I've skipped.
After I'll try also the audio quality and I'll let you know...
Thanks for your interest... this is a very strange case :-o
Alex
-
Hi BlobRana. Why you said this? Help me to understand because I'm very confused :-?
I've found several schematics on the net to use an ATX PSU. There are also circuits to turn on it with a switch as you can do in a PC.
In addition, you can find on Aminet little software to turn-off the computer directly from the shell only with ATX PSU...
Thanks
Alex
-
My A1200D is running from a cannibalised ATX PSU with no problems. You just have to ground the PS_ON line (grey I think, but seriously do not take my word for that).
-
Never trust wiring loom colours..
I just double checked on my mini ATX, and its PS_ON is purple, but according to the ATX spec it should be green :pissed:
Since my A1200 is laid bare on the bench with it's top casing off, I just stuck a simple toggle switch between PS_ON and GND. I dare say when I bung it into a proper case I'll use something like the circuit on Stedys site to use a nicer non-latching push switch.
Thinking about it, I might use a PIC to replace the debounce and flipflop, with the added bonus that it could time the duration the switch was held in and do a reset if it was held for >2-3 secs, or even have an input from the miggy for a soft power off too..
But now I'm waffling out loud and not helping at all... :insane:
-
I never trust any of these particular so called "colours". Nobody ever offered me any tangible proof they exist :lol:
-
I've just measured voltages from PSU and inside the A1200.
These are the values:
ATX PSU
-------
OUTPUT:
+ 11,68V
+ 5,15V
A1200 (without Apollo):
+ 11,95V
+ 4,58 V
A1200 (with Apollo):
+ 11,86V
+ 4,24V
A500+ PSU
---------
OUTPUT:
+ 12,00V
+ 5,31V
A1200 (without Apollo):
+ 12,35V
+ 5,15V
A1200 (with Apollo):
+ 12,61V
+ 5,00V
It's so strange... :-? :-o :-?
The A500 PSU provides higher voltages than the 200W ATX PSU. In addition the ATX works perfectly inside a PC and, as I just said, I've tested another ATX PSU, that was a 400W.
Looking to the values, the main problem seems to be the +5V, that is too low when I attach the Apollo. Probably it needs more energy so the Amiga doesn't start.
... I can't understand :pissed:
Alex
-
Most likely your PC is drawing most juice from the 3.3v rail so that the 5VDC one has less impact on reliability.
-
unfortunately, the problem still with the UNUSED 3.3volt output, when used on an Amiga.
Some "cheap" ATX PSUs, when used on Amiga, gives unreliable output on the 5 volt rail (see at your 4.24 volt with Apollo installed).
Often (see at the ATX PSU specs) the 3.3 and 5 v power output, are given together (as total output Amperes)
When we use it on an Amiga, those ATX PSUs, works in an unbalanced way.
The solution, would be to use more reliable (more expensive ATX PSUs, with indipendently regulated output) or give to the PSU a "dummy" charge to the 3.3 volt output.
EDIT- erm . . . about how to achieve a reliable charge on the 3.3 volts line, any help wiil be apreciated :-)
A little personal note:
i own a PowerTower4000 (but its the same even on a PowerTower1200) with those little PCB with row leds-2 drive transistors and few polarization resistors).
Seen that i had the 3.3volt ATX output line there doing nothing, i have used it instead of the 5 volt to power the leds PCB (an easy way to dimm all those leds light).
Result . . . those very, very low power drain, from the 3.3volt ATX output, screws the whole PSU output (not so much but it does).
-
It seemed a reasonable solution so I've tried but it didn't work.
As "dummy charge" I've used some car lights with a value from 5w to 45w. Nothing happens :-(
I'll look for a better ATX supply or for an old AT...
Thanks for your interest.
Alex
-
mhhh, interesting.
Just for the sake of . . . have you checked the +5volt line when the PSU is installed in the PC?
About all the ATX PSUs, has a wire tyed to the mobo (sense), that detect and compensate the 3.3Volts output.
Some others has this compensation line, even on the 5 volt rail. (it compensate the loss of the wires, and "says" to the PSU to raise the voltage if needed).
Pin 11> 3.3volt sense
About the 5volt sense, i think that only some so called "server ATX PSUs" have it.
Anyway, probably your PSU is only tired ;-)
EDIT- thers a guy her on AOrg (sorry don't remember the nick) who is using a "Antec True Precision" bla, bla that sounds interesting.
http://www.silentpcreview.com/Sections+index-req-printpage-artid-61.html
a very impressive test.
-
I have an old A1200 with a rewired PC supply and I have had similar problems in the past. In my case I discovered that the problem was inside the Amiga. I had wired all my additional internal goodies to the same plug that supplies the floppy drive et al. The problem is that this connector is not very secure and makes bad contact. In addition when the machine draws a big current load (such as at bootup) the small plug just can't deliver, especially if the connection is also dodgy (as in my case). I guess the solution would be to change the plug and put in a heavier duty one, but that would involve a lot of soldering and my motherboard is already tired and covered in my amateur solder jobs, so for now I just wiggle the connector from time to time when I have a problem and it goes back to normal for a while. Your milage may vary ....
-
I'm running a powershot (http://www.montek.com/cart/catalog/Amiga-Powershot-CD32-p-27708.html) cable from a 430 watt AT (not ATX) server P/S.
This unit has a power switch on the back, neater than having an 18 inch cable draped across the desk.
It runs my 1200 with lots of extras and plenty to spare.
-
@starf81
Did you try connecting the car bulbs to the 3.3V supply?
Measure the voltage at the PWR-OK (pin 8, wire colour Grey), it it above 2.0V?
Have you re-wired the Amiga power plug to the ATX PSU?
Try connecting pins 1 to 11 (3.3V to 3.3V sense) and see if it helps.
My 6 year old ATX PSU powers my Amiga fine. I will check a spare (more modern) PSU if I get a chance and see how well that works.
Ian
-
Hi Stedy!
Yes, I've connected car bulbs to the 3.3V. Obviously they turned very light but it was a good charge for the PSU since I listened to its fan spun up.
However, I've tried to use this charge also on the +5V and +12V channels.
I've not measured pin 8 voltage but I'll do...
Regarding the plug, I've used my original A1200 PSU cable re-wired directly to the ATX supply. So the plug is the Commodore one supplied with the Amiga.
I'll try to connect pins 1 and 11, too.
Regarding the age, I bought this PSU exactly six years ago (it was June '99) while the other one I've tested was been bought more or less 18 months ago.
Thanks for your interest
Alex
-
i'm a little confused now:
"Yes, I've connected car bulbs to the 3.3V. Obviously they turned very light but it was a good charge for the PSU since I listened to its fan spun up.
However, I've tried to use this charge also on the +5V and +12V channels."
but . . . have you done this measurements, without any charges (ie with th PSU plugged to your A1200) on the others lines?
Its absolutely uneseful to test a PSU in such way!
To be 100% sure that your PSU (or PSUs in this case) is gone, install it on the PC and test the +5volt line.
If the 5volt is within tollerance and the PC works, could be a problem on your A1200/CPU card that drain too much current (ie a short somewhere or the wires plug)
-
Had the same problem use the blue (-12)volt cable on the atx socket for ground that solved my problem try messuering b4 connecting tho to be on the safe side
adonay :-D
-
Absurd!
I've tried to connect the ATX PSU through the 4-pins floppy port adding the -12V to the standard Amiga PSU port (I've read some towers are connected in this way) and... IT WORKS!!!
I really can't understand, it's so strange. In your opinion, what could be the difference?
However, the Amiga is still very unstable. So my problem wasn't only the poor PSU... :boohoo:
At the moment this is my configuration:
- A1200 rev 1D4 (I've removed E123C and E125C component as suggested in all website).
- ROM 3.1
- Apollo 1240 w/ 32MB Ram
- Elbox Fast-ATA PowerFlyer Mk.II w/ HD 3.2 GB and Pioneer DVD-R 106
The computer is fully stable only when I use the original configuration.
If I add only the Apollo, it seems to work but sometimes reboot.
If I add only the Fast-ATA, it works quite well but continues to reboot in random way.
If I mount both the Apollo and the Fast-Ata... well, this is the most funny moment: red screen, yellow screen, black screen (sometimes with horizontal bands) or it could have also a normal behaviour for some minutes but after it reboot.
Why??? :boohoo:
I'm trying everything... and after every test I'm always more confused. :-o
Any suggestion?
I'm been out from Amiga world for many years and now I've lost my familiarity with this system, specially in the hardware side. So I really don't know what I have to do :-( ... and I'm afraid of burning the 1200 motherboard or some expansion card.
Alex
-
@starf81
Powering the A1200 motherboard via the floppy port is pretty common. My A1200T's motherboard is powered from the case PSU via this and also via all 5 voltage rails of the rear connector (most people just use this for the -12VDC line).
Naturally all other drives / fans are powered direct from the PSU too.
With this dual connection arrangement, less current has to flow throught any single point on the motherboard. Some accelerator cards (eg my BPPC 040 + BVision + RAM) can require quite some power, more than I would feel comfortable pumping through my ageing A1200 motherboard via a single place.
-
@Karlos
Just tested.
It's the same: Fast-Ata with Apollo don't start, without the Apollo, my 1200 can load the WB but it crashes after few seconds.
Could the Fast-Ata not working well without an accelerator card?
Alex
-
starf81 wrote:
Could the Fast-Ata not working well without an accelerator card?
Possibly; I don't know for a fact. The Fast ATA probably doesn't give any real speed up on a bare 020 A1200 with no fast ram anyway and I doubt the creators of the hardware envisaged it being used in such a fashion.
-
Well... just tested again the 1200 with Fast-Ata and Apollo. It started, loaded the WB and after about 30 second the green power led blinked... another crash.
I'm going mad :crazy:
Alex
-
@starf81:
Why not just use the A500 PSU you said worked?
/Patrik
-
Try to connect the Apollo NOT fully inserted (pull it ~1mm out).
Sometimes the edge connector, lacks in contact.
btw . . now how much is the +5 volt rail? (measured on the Apollo)
-
Its your lucky day i,ve a AT psu wired with an amiga cable which powered a A1200 Tower with 040 and extra,s ,the towers sat doing nothing as i got a compact flash to ide converter and dont need a big psu anymore, mail me if ya want it jabar@jabar.karoo.co.uk :-)
-
Yes, I've already tried to check the edge connectors.
Regarding the +5, where can I measure it on the Apollo? I don't have a schemathic to identify the +5v rail. I can only find the +12 where I wire the fan.
Alex
-
One of the pins on the oscillator should be 5VDC - you'd need to check the pinout for it though.
-
@starf81,
Check for the +5V and 0V here:
(http://www.ianstedman.co.uk/Downloads/Apollo-measure.jpg)
I have indicated where to probe, I can't remember which is +5V and 0V but you will soon see on your DMM.
Once you find which is +5V and 0V, connect from your ATX PSU to your Apollo card using one of the floppy drive connectors of the PSU. It may sound daft but I had to do a similar thing to get my damn SX32 to work, once I had done that, it worked fine.
As a guide, the +5V rail should be above 4.85 Volts when measured with a DMM for the CPU to work, this allows for 100mv of noise the meter will not 'see'.
-
Well, just changed the Apollo with a Blizzard 1260 all work correctly. Strange, very strange... the previous Apollo's owner confirms me that it works well on its machine.
However, now my A1200 is 100% working!!!
Thanks for your help!
Alex