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Mac II relife

E

Elvi

Experienced Member
Joined
Nov 23, 2011
Messages
275
Location
Munsala, Finland
Ok so some of you probably have seen this macintosh II i have on my site, now heres the thing, it won't start at all aka no poweron after i hit the power button, been trying to figure it out slightly over the years but as i'm not really used to mac's it's not so easy.
From left to right the psu has 1 orange, 4 red, 5-6 black 1 yellow and 1 white cable, anyone know if there is a way to trick the psu to starting on it's own if you plug in the power cable like you can do with atx psu's? atleast then i'd know if it's the psu or something else.
 
For starters, the two 3.6v cells are probably dead. They are needed to supply the latch power foer the PSU to tuen on when you press the power button.
A good substitute for one 3.6v cell is two 1.5v AA batteries.
 
Any ideas if it's possbile to hotwire the psu or the batteries so it would start up?

Edit: just mesured the 2 batteries and they arn't dead but i doubt they have enough charge to start the pc, nr 1 3.20V, nr2 0.15V so they arn't dead at all but they might aswell be since they are lithiums.
 
Last edited:
Elvi said:
Any ideas if it's possbile to hotwire the psu or the batteries so it would start up?

Edit: just mesured the 2 batteries and they arn't dead but i doubt they have enough charge to start the pc, nr 1 3.20V, nr2 0.15V so they arn't dead at all but they might aswell be since they are lithiums.
Click to expand...

Before you go trying to hotwire the PSU, I would replace the batteries, though it sounds like NR1 is still good, but for sake of argument I would replace both. You shouldnt need to replace them with exact matches, like NeXT said you can replace each one with 2x AA or AAA cell batteries. Being you are from Finland I cant tell you where to find battery holders, but if nothing else they are cheap on ebay from china. I have done this in a number of vintage computers, using AA/AAA battery holders makes future replacements VERY easy, plus you can mount the battery holder away from the board so if they leak they wont corrode the board.
 
I don't wanna put out any money on this thing before i even know if it's the batteries or the psu that's bad, read somewhere it "should" start with 3.0-6.5V on the pfw line, the white cable so... i tried to jumper from the red +5v to the pfw and nothing, with the mobo disconnected ofcourse.
So any other ideas?
 
Just tried to wire in a 3v cell on the battery that didn't have much power left... nothing still doesn't start.

Edit: also suddenly the second battery is showing 2-2.5v charge o_O how is that possible if it's a lithium battery!?
 
Last edited:
Elvi said:
Is it possible to start this mac with a at or atx psu at all?
Click to expand...

Yes - I have a Mac II and a IIx running on ATX power supplies. Here's the pinout for the power connector:

Pin # Function
----- --------
1 +12V
2 +5V
3 +5V
4 +5V
5 +5V
6 +5V
7 Ground
8 Ground
9 Ground
10 Ground
11 Ground
12 Ground
13 N/C
14 -12V
15 /PFW

http://support.apple.com/kb/TA39976?viewlocale=en_US

It may not be a good long-term solution, but at least it will let you test the board.
 
Another issue might be capacitors, I had to rework both of my IIx machines because of leaky caps, the original II will have the same issues. One of the batteries hold PRAM info while the other jump starts the computer (and that one goes dead first). Try reseating the ROM SIMM (forget if that model had SIMM or chips).
 
scott-k said:
Yes - I have a Mac II and a IIx running on ATX power supplies. Here's the pinout for the power connector:

Pin # Function
----- --------
1 +12V
2 +5V
3 +5V
4 +5V
5 +5V
6 +5V
7 Ground
8 Ground
9 Ground
10 Ground
11 Ground
12 Ground
13 N/C
14 -12V
15 /PFW

http://support.apple.com/kb/TA39976?viewlocale=en_US

It may not be a good long-term solution, but at least it will let you test the board.
Click to expand...

I've seen these numbers before but i can't really make heads or tales off them especially pin 13 and 15, doubt a atx or at psu has those.

If i had some shematics then i probably could work it out some day but i've seen none on the net for either at or atx.
 
Elvi said:
I've seen these numbers before but i can't really make heads or tales off them especially pin 13 and 15, doubt a atx or at psu has those.

If i had some shematics then i probably could work it out some day but i've seen none on the net for either at or atx.
Click to expand...

I am guessing N/C means "No Connection", as it frequently does in pinouts. PFW is power-fail/power-on circuit, something which I am pretty sure doesn't work the same on ATX, and something that would be dangerous to "fake", its purpose in the Mac is to 1. respond to power key on ADB keyboard (less critical) and 2. be able to initiate SHUT DOWN on the Mac in case of thermal runaway or other damaging events. If you really want to fake it and power-up with an ATX supply (and very likely destroy the board) +5v should in theory be applied to PFW to bring the power online.
 
I really don't have anything to loose here as i have no spare parts to test with and it won't turn on at all, i guess this would be easier with an AT psu as if the PFW is the one that needs +5 and the rest of the pinns are allready on a AT psu so i'd just have to hit the on switch on the psu... hopefully, thoughts?
 
Elvi said:
I really don't have anything to loose here as i have no spare parts to test with and it won't turn on at all, i guess this would be easier with an AT psu as if the PFW is the one that needs +5 and the rest of the pinns are allready on a AT psu so i'd just have to hit the on switch on the psu... hopefully, thoughts?
Click to expand...

AT or ATX, either one should supply the voltages needed, but either one will leave the PFW not working as it should, try it at your own risk, but its likely you will toast that thing.

Best bet if you want to see this thing live again would be to replace all the electrolytic capacitors, those are the likely culprits to why its not powering on now. I would say after you have replaced those, and put fresh PRAM batteries in it and it STILL wont power on.....then I would say you have nothing more to loose, those are NOT expensive things to try first, you are looking at about $10-15USD (with postage) in parts and an hour of time. Those shouldn't be TOO expensive of parts in Finland either, there has to be SOME kind of electronics store (local or mail-order) that sells those types of parts, even if its a touch more than they would cost here in the states, if nothing else you can order that stuff for next to nothing from china it you have the time to wait.

In the end its your stuff, if you want to just "apply power" and see, its up to you, just saying I would be trying a few things before that step.
 
Shouldn't the capacitor tops be bulgy or leaking if they have failed? i can't see any of that.
Also it doesn't tell me if the PSU itself is bad or not.
 
Elvi said:
I've seen these numbers before but i can't really make heads or tales off them especially pin 13 and 15, doubt a atx or at psu has those.

If i had some schematics then i probably could work it out some day but i've seen none on the net for either at or atx.
Click to expand...

This is what your connector should look like:


http://i1246.photobucket.com/albums/gg614/scott-k/power.jpg


1 Yellow (+12V)
3 Red (+5V)
12 Black (GND)
14 Blue (-12V)

Ground the green wire on the ATX power supply to turn it on.
This powers the Mac directly, so you don't need pin 15.
 
scott-k said:
1 Yellow (+12V)
3 Red (+5V)
12 Black (GND)
14 Blue (-12V)

Ground the green wire on the ATX power supply to turn it on.
This powers the Mac directly, so you don't need pin 15.
Click to expand...

Guess this would even be easier with an AT psu, i have a few of those, just start the psu and away we go... hopefully.

scott-k said:
The caps probably won't bulge... Look for a greasy stain around them:

http://i1246.photobucket.com/albums/gg614/scott-k/leaky.jpg
Click to expand...

Uh oh, i saw a few that i think have leaked, not good :/ never thought those small things were caps tho.
 
HAHA would you look at that, it booted right up with a AT psu, nothing wrong except that the OS is busted but i knew that from before, and as i don't have any OS diskettes i can't fix it, the hd seems ok even with the leaking caps... for now.

Thanks alot scott-k now i atleast know that the mobo is somewhat ok so i can play with it, maybe i should open up the mac psu and check it's innards to see how it is, also noticed that the traces to the button has started to flake, that might be a reason it's not booting either.
 
Does anyone have the schematic for this mac or know where to find one? trying to figure out of the power button leads are busted, 1 of the 6 pinns seem to be minus and goes almost directly to 1 of the batteries, the other one along side it go to 1 of the caps so i know these 2 work atleast, the other 4 is another matter, i realy can't see where they are going.
 
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