Amiga 3000 Power Supply
Information Packet
12/9/1994
Text by
Brett Johnson
ip47@jove.acs.unt.edu
HTML code By
Scandinavian User Group
We have changed to an pc power suply 230W on our A3000UX (T) .
# 0. Table of Contents #
0. Table of Contents 1. Background/Introduction 2. Disclaimer/Warning 3. Using a PC Power Supply on your Amiga 3000 4. General Amiga 3000 Power Supply Information 5. Letters and Real Life Experiences 6. Amiga 3000 Power Supply Technical Information 7. Power Connector: Hard Disk 8. Power Connector: Floppy Drive 9. Power Connector: Fan 10. Power Connector: Motherboard
# 1. Background/Introduction #
On December 31, 1993 at 2:00pm I was attempting to do a null modem
hookup between an HP 9000/360 and my Amiga 3000. I do null modem
hookups all of the time, so the experience was nothing new to me. When
I plugged in the serial cable to my live Amiga 3000, it suddenly became
dead. Later on (after a totally incompetent repairman fried the entire
board plus 10 megs of ram) I discovered a new power supply and an 8520
chip would have solved all of my problems. If I would have been able
to get a good power supply, I might have figured out my problems and
fixed the whole thing myself before someone else could have destroyed
my pride and joy...
This FAQ-type document contains much of the necessary information
to check out your existing power supply or to replace it with a PC one.
I got much of this information from a repairman at PSI (215-443-8330;
they service Amigas and stock many of the chips and parts--so you might
not need this FAQ after all...).
I have come up with my own labeling scheme for the connector
diagrams below. It is extremely simple and easy to learn. Inside the
pin there will be a number followed by a letter. The number is the
relative pin number I have assigned to it for simple labeling purposes.
The letter following it stands for the wire color for that pin. My
mwire color codes are as follows:
B: Blue
Br: Brown
G: Green
O: Orange
P: Purple
R: Red
W: White
Y: Yellow
Something like "3B" would mean: Pin 3-Blue. I have also included a
second diagram with just the plug and voltages (this may be more useful
to some people; it is the same orientation as the first diagram).
Please notice the Title and Orientation Box at the top of each
Connector-Section. If the orientation says "Looking At Back Of Plug,"
you are looking at the place where the wires COME INTO the plug (the
other side actually goes into something). If the orientation says
"Looking Straight Into Plug," you are looking directly at the pins with
the wires coming out from the back (ie. you could plug it into your
head if you brought it straight towards you--not recommended, though).
# 2. Disclaimer/Warning #
I make no claim to be a computer repairman or electrician. To my
knowledge all of the information presented here is correct. You use
this information at your own risk. Playing with power supplies can be
extremely dangerous if you do not know what you are doing (to yourself
and the computer). I cannot be held responsible for any
damage/injuries that occur due to carelessness or any other factor.
NOTE: If your power supply died, there is probably a good reason!
You might want to have your computer checked by an Authorized Commodore
Engineer to make sure your computer doesn't end up like my first A3000.
If you plug in the power supply and the chips get hot, SOMETHING IS
WRONG AND YOU SHOULD SHUT OFF THE POWER IMMEDIATELY OR YOU WILL NOT
HAVE A SYSTEM LEFT!!! [Note: The 68030, U202, U203, U701, and U714
normally run hot. A few chips that shouldn't get hot are: the 8520's;
chip RAM; fast RAM--there will naturally be a little heat, but not too
much.]
Note for Lawyers: This is not a commercial advertisement (or an
advertisement at all). All companies, special parts, or whatever
mentioned or implied have been patented/copyrighted/trademarked by
their respective owners.
And now on to our program...
# 3. Using a PC Power Supply on your Amiga 3000 #
Although I have never personally tried this, it is possible to use
a PC power supply on your Amiga. Others have done this with success.
The Amiga uses custom power connectors, so this needs to be taken into
consideration. Also watch the wiring colors. These colors have
specific meanings. It would be easier in the future to match the Amiga
colors with the new supply. It is also probable that the PC power
supply will not fit inside the Amiga casing. If this is true, make
sure the wire is thick enough to avoid any voltage loss. [see below]
3000 Power Supply Wire Length Specification (External--near computer)
Motherboard Connector: 3'
Hard Disk Connector: 3', 4'2"
Floppy Connector: 3', 3'6"
Fan Connector: 1'8" [for using old PS fan]
Power Switch: 2'
PC Power & Cooling (1-800-722-6555) has an option where they can
refurbish your old/dead power supply (they haven't done Amigas before,
so you would need to send them the following diagrams). The cost (as
of November 1994) was $140-$160. The new unit would be:
Watts: 220
+5V: 23 amps
+12V: 8-9 amps
-5V: 0.5 amps
-12V: 0.5 amps
As of this date, this is a little less than the going cost of a 200
Watt Amiga supply. The only thing a PC supply would be lacking is the
TIC signal (+5V 60 Cycle Square Wave).
For a PC supply without TIC (+5V 60 Cycle Square Wave), change
Jumper J350 to VSYNC (most are on TIC). TIC provides sync to something
like a genlock. Setting J350 to VSYNC gets the signal from an internal
source.
# 4. General Amiga 3000 Power Supply Information #
Green Wire (+5V) is a special line to power up something like a genlock. All of the like colored wires come together in the Power Supply (except for the Red Fan Wire which gets +12V--as opposed to the -12V Red wire on the Motherboard). The original A3000 power supply should run at full speed when not connected to anything. In other words, it does not need a load to run properly (at least mine doesn't). If the fan power line becomes unplugged, the original A3000 power supply will not run (for safety reasons, of course).
TIC is a +5V 60 Cycle Square Wave that is used to sync something like a genlock. The TIC signal can come from an internal (your computer) or external source (power supply). Change Jumper J350 to VSYNC (most are on TIC) if your power supply does not furnish this signal. Setting this jumper to VSYNC gets the signal from an internal source.
Noisy Fans. If a fan makes a noise, obviously there something wrong. One probable cause is a wire has gotten too close to the blades. Simply opening the power supply and moving the wire will solve the problem. Cleaning the fan might be a good idea also. WARNING: A power supply has large capacitors that hold a charge after the unit has been unplugged! [I have verified this myself; very impressive sparks.] Wait about 10 minutes after unplugging the power supply from the wall before servicing.
# 5. Letters and Real Life Experiences #
Dirk Hill (dirk@shell.portal.com) Monday, December 5, 1994 I spent most of Saturday making a PC power supply fit into my A3000. I found a 145Watt supply for about $8. I pulled it out of the case and also took the 3000 PS apart. It required a fair amount of soldering to get it to fit. Almost all the wires needed to be extended. The four important connections (fan, power cord receptacle, switch, and output voltage) were not in the same areas as on the 3000 supply. The PCboard was also about 1/8 inch too wide. I put electrical tape on the bottom to keep the casing stand-offs from shorting. I also put some nylon stand-offs in the holes where the bolts used to go. It was necessary to bend the heatsink flanges over to fit in the 3000 PS's casing. The only real problem I had was the signal DC-OK on the new power supply. When I powered up the supply, unconnected, all the voltages were there. When I plugged it into the 3000 MB and turned on the supply, there was no power. Eventually I figured out that the DC-OK needed to be connected to the +5V. I tied it to the +5V-SEP line. (That was what was silkscreened on to the old supply. 14Green on Brett's connector diagram.) I don't know if this is what C= had in mind for that line but it seems to work. If you are looking to replace your supply with a PC supply then a few things to look for are: 1. Push button on/off. I was able to use the switch already on the new supply. This save some soldering time. 2. Small PC board. This is hard to tell from outside the case but in general look for a case very similar in dimensions as the 3000's supply. It can be a little taller (you can always bend the heatsink flanges as I did.) The one I have was advertised as a mini-tower PS. 3. At least 135Watts. More is better; but the PCB size starts to increase with wattage. Dirk Hill (dirk@shell.portal.com) Monday, December 8, 1994 The +5VID [Purple Wire] is separated from the rest of the +5V lines. I suspect it goes to the Video slot. +5VID only connects to the logic +5V in the power supply through a diode/capacitor/resistor circuit. I imagine this is to keep the high frequencies from the logic from getting into the video circuitry. The +5_USER [Green Wire] goes to the video port (pin 12) and is used to pull up pin 14 on the Parallel port (through a resistor). (From this I now know I hooked up the DC_OK signal on the PC PS wrong. It should be tied to one of the other +5V lines. And the +5_USER should have it's own separate line from the PS.) The +12V and -12V [Orange, Red Wire] go through diodes and to the Serial port (both) and video port (+12V) pin 23.
# 6. Amiga 3000 Power Supply Technical Information #
Colors in General Terms (THESE MAY NOT ALWAYS APPLY!!!):
Orange = +12V
Yellow = +5V
Blue = Ground
Less Common Colors:
Purple = +5V Video
Red = -12V (Except on Fan Power Line)
Green = +5V User
White = -5V
Brown = TIC
*** Knowing Commodore designs, these colors may be subject to ***
*** change! In other words, if you don't know, get a volt meter ***
*** or look it up! ***
The original Amiga 3000 Power Supply:
Model: PB-5161-1
Level: 3
Watts: 135
Input: 120V-4A 60Hz
OutPut: 5Vdc/17.25A 12Vdc/3A
[5Vdc(user)/0.75A 5Vdc(video)/0.75A]
-5Vdc/0.2A -12Vdc/0.3A
# 7.1 Power Connector (Hard Disk) # # * Looking At Back Of Plug * #
Figure H1.1
________________________________
/ \
/ __ __ __ __ \
| / \ / \ / \ / \ |
| | 1Y | | 2B | | 3B | | 4O | |
| \__/ \__/ \__/ \__/ |
| |
|_________________________ ________|
| |
|_|
Pin 1: Yellow +5V
Pin 2: Blue Ground
Pin 3: Blue Ground
Pin 4: Orange +12V
------------
# 7.2 Power Connector (Hard Disk) # # * Looking At Back Of Plug * #
Figure H1.2
________________________________
/ \
/ __ __ __ __ \
| / \ / \ / \ / \ |
| | +5 | |GND | |GND | |+12 | |
| \__/ \__/ \__/ \__/ |
| |
|_________________________ ________|
| |
|_|
# 8.1 Power Connector (Floppy) # # * Looking At Back Of Plug * #
Figure F1.1
_ _____ _
| | | | | |
| |_______________| |_______________| |
| |
| ____ ____ ____ ____ |
| | | | | | | | | |
| | 1Y | | 2B | | 3B | | 4O | |
| |____| |____| |____| |____| |
| |
|__________ ____________________________|
| |
|_|
Pin 1: Yellow +5V
Pin 2: Blue Ground
Pin 3: Blue Ground
Pin 4: Orange +12V
# 8.2 Power Connector (Floppy) # # * Looking At Back Of Plug * #
Figure F1.2
_ _____ _
| | | | | |
| |_______________| |_______________| |
| |
| ____ ____ ____ ____ |
| | | | | | | | | |
| | +5 | |GND | |GND | |+12 | |
| |____| |____| |____| |____| |
| |
|__________ ____________________________|
| |
|_|
# 9. Power Connector (Fan) # # * Looking Straight Into Plug * #
Figure Fan.1
#############
# #
# o o #
# #
##___###___##
^ ^
| |__Blue Ground
|
|________Red +12V/0.13A
* The fan will not run if these two wires are swapped.
# 10.1 Power Connector (Motherboard) # # * Looking At Back Of Plug * #
Figure M1.1
________
| CLIP |
___________________|________|___________________
| |
| ____ ____ ____ ____ ____ |
| | | | | | | | | | | |
| | 1Y | | 2Y | | 3Y | | 4Y | | 5P | |
| |____| |____| \__/ |____| |____| |
| |
| ___ ____ ____ ___ ____ |
| | \ | | | | | \ | | |
| | 6B | | 7B | | 8B | | 9B | |10B | |
| |___/ |____| |____| |___/ |____| |
| |
| ____ ____ __ ____ ____ |
| | | | | / \ | | | | |
| |11O | |12R | |13Br| |14G | |15W | |
| |____| |____| |____| |____| |____| |
| |
|________________________________________________|
Pin 1: Yellow +5V
Pin 2: Yellow +5V
Pin 3: Yellow +5V
Pin 4: Yellow +5V
Pin 5: Purple +5V Video
Pin 6: Blue Ground
Pin 7: Blue Ground
Pin 8: Blue Ground
Pin 9: Blue Ground
Pin 10: Blue Ground
Pin 11: Orange +12V
Pin 12: Red -12V
Pin 13: Brown TIC
Pin 14: Green +5V User
Pin 15: White -5V
# 10.2 Power Connector (Motherboard) # # * Looking At Back Of Plug * #
Figure M1.2
________
| CLIP |
___________________|________|___________________
| |
| ____ ____ ____ ____ ____ |
| | | | | | | | | | | |
| | +5 | | +5 | | +5 | | +5 | | +5 | |
| |____| |____| \__/ |____| |____| |
| |
| ___ ____ ____ ___ ____ |
| | \ | | | | | \ | | |
| |GND | |GND | |GND | |GND | |GND | |
| |___/ |____| |____| |___/ |____| |
| |
| ____ ____ __ ____ ____ |
| | | | | / \ | | | | |
| |+12 | |-12 | |TIC | | +5 | | -5 | |
| |____| |____| |____| |____| |____| |
| |
|________________________________________________|
Acknowledgements and Thanks: Myself for doing all of this. Richard Huffnagle @ PSI PC Power & Cooling for talking to me. The people who send me letters and feedback.