Pinout and info on old Mac II power supply (Astec AA13780)?

[joemck2004]

I found an old Astec AA13780 power supply that someone threw out. It's Apple part number 699-0389. Some Googling told me that it's for the Macintosh II. There are a few things I'd like to know:
-Is there a way to find out if it works without plugging it in and seeing if it blows up? (Any resistances I could mesaure, etc.)
-How do I turn it on? I see a yellow and a white wire on the connector that are apart from the others and suspect that those go to the switch.
-What is its pinout?

Looking at its connector, the wires are: 1 thick orange, 2 thin red, 3 thick red, 6 black, an empty pin, 1 yellow and 1 white. It says it has three voltages: +5 (18A), +12 (2.5A) and -12 (1A). At one end is an input socket and a passthrough for a monitor. At the other end is a LED, a fan on the side and the output power connector. There is a sticker giving the date code 8849T, revision 04B and serial number 585193360.

I don't have a Macintosh II to use it with, but it would be nice to have a higher power DC power supply for electronic projects.

Thanks in advance for any information you might have about it.

 

[PeteWeedon]

Hi,

Apple Macintosh Family Hardware Reference Manual (ISBN 0-201-19255-1) published by Addison-Wesley gives the following:

All power for the main logic board, internal disk drives, fan and Nubus cards in the Macintosh II computer is provided by the Macintosh II power supply. The power supply is switched on by a signal line on the ADB connector and is switched off by a signal generated by software.

The Macintosh II power supply can accept any AC line voltage from 90V to 140V (RMS) and 170V to 270V at any single phase input line frequency from 47 to 64 Hz. The power supply generates output DC voltages of -12, +12 and +5 V.

There's a diagram which I can't reproduce here but I summarise below:

Pin #1: +12 V
Pin #2: +5 V
Pin #3: +5 V
Pin #4: +5 V
Pin #5: +5 V
Pin #6: +5 V
Pin #7: Ground
Pin #8: Ground
Pin #9: Ground
Pin #10: Ground
Pin #11: Ground
Pin #12: Ground
Pin #13: No connection
Pin #14: -12 V
Pin #15: /PFW

You should be able to identify pin #13 fairly easily and work out the rest from that.

Minimum load: +5 V: 3.0 Amps, +12 V: 20 mA, -12 V: 20 mA
Maximum load: +5 V: 18 Amps, +12 V: 2.5 Amps, -12 V: 1 Amp.
Peak* load: +5 V: 18 Amps, +12 V: 4.5* Amps, -12 V: 1 Amp.

* For a period of 15 Seconds, maximum 10% duty cycle. The +12 V may drop to 11.0 V during the peak load; the +5 V and -12 V supplies conform to the listed limits.

The above is a quick extract of the main stuff. If you need more info, e.g. about the /PFW signal, post here again and I'll dig deeper into the text. At least the above figures should enable you to prepare some suitable dummy load resistors.


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!

 

[joemck2004]

Thanks! Could you please see if it explains how to use the /PFW signal. Also, does it say what happens if the minimum load isn't met?

-Joe McKenzie

 

[PeteWeedon]

Hi Joe,

I've had a quick look but not found anything yet. Bear with me, I'll keep looking.

In the meantime, someone else may know and post.

As regards the minimum load, I understand that the PSU won't run at all unless the load on the main output line (most probably the +5 V) exceeds the minimum. If the load on the other lines is less than minimum, their regulation may not be adequate.

In the interest of brevity, I didn't feed you everything the book said; for instance, the PSU is short-circuit protected.

I'll post here again when I've had the opportunity to study the book some more.


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!

 

[joemck2004]

So all I have to do to get power is plug it in and put on a load? If so, I don't need the info on the /PFW signal. I assumed it had to do with turning it on.

I'm used to the type of PSU that either has a switch on the side or a couple wires you wire to a switch.

 

[PeteWeedon]

I didn't say that. Or, at least, I didn't mean to say that.

The power switch in the keyboard of the Mac II shorts a line to ground. The bit I haven't confirmed yet is whether that line is directly connected to /PFW or if there's some other circuitry in between.

Need more time!!!


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!

 

[PeteWeedon]

Just re-read my last post and see that it is a bit ambiguous.

I didn't mean to convey that 'all you have to do to get power is plug it in and put on a load.'.

Yes, the /PFW signal is associated with switching the PSU on and off. The way the book is divided into different sections makes it a bit laborious to understand whether there's any level changing or other circuitry between the power switch line in the keyboard and the /PFW pin on the PSU.

If you can wait a bit longer, I'll keep digging.


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!

 

[joemck2004]

Please try to find out how I can turn the thing on.

-Joe McKenzzie

 

[PeteWeedon]

OK, Joe,

I'm going to have a serious look through the book now.

Sorry not to have done it before but things kept cropping up!


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!

 

[PeteWeedon]

Hi there, Joe,

I've found some more description of the Mac II power control circuit:

Starting with the PSU off, a voltage between +3 and +6.5 Volts applied to the /PFW line will switch the PSU on.

The Mac II power control circuit then feeds back a signal derived from the +5 Volt output to the /PFW line to keep it on.

With the PSU on, pulling the /PFW line low (i.e. below +3 Volts) causes the PSU to shut down.

The PSU itself can also control the /PFW line and hence shut itself down, e.g. if its primary switching device heat-sink temperature exceeds 125 degrees Centigrade or if it senses a line input voltage failure. In the latter case, it pulls /PFW below +0.6 Volts.

So it looks as though you'll have to contrive some diode-resistor and/or relay logic to apply +3 to +6.5 Volts (from a battery?) to /PFW to switch the PSU on, feed back a sniff from the +5 Volt line to keep it on and to pull /PFW low to switch it all off, all without the three aspects conflicting. I'll leave you to design that!!

I hope that I've helped.


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!

 

[PeteWeedon]

Joe,

An afterthought:

I don't think you need bother to use the switch - it's a momentary contact type and works through the Mac II internal logic.

All I wrote in my previous post assumes you've applied primary mains power to the PSU.


Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!

 

[joemck2004]

Thanks. One question: Where's the Mac II get the 3-6.5 volts to turn on? From the internal battery?

 

[PeteWeedon]

Yes.

Best regards,

Pete W.

If you can keep your head when all about you are losing theirs - you haven't seen the latest Change Note!