IIe power supply maintenance

I have been having PSU problems too. But mine never made that buzzing noise. If the IIe is making those beeps, test the output with a voltage meter. Try opening the PSU and see if anything is looking dead.

what i ended up doing is ordering 2 PSU's from GSE-Reactive, and in the meantime, i took an old ATX power supply, got the pinout diagram, and stripped the -12v,+12v,-5v,+5v, 2 grounds and wired them to the IIe PSU connector, i added a swtich inbetween the ATX PWR_ON and a ground, and as long as its grounded it turns, on, its working fine untill i get the PSU boards in the mail...

That's a good idea, I should try doing that since my IIe PSU is also dead. I would recommend looking into your dead apple IIe PSU and just see what went wrong.

oh i did, i thought i located the problem, with the bzz and replaced the big transformer in the middle with one of my ohter power supply's, and it did the same thing, so i repalced the capacitors, and it didn't buzz any more.
its ok im getting the PSU boards for cost of shipping from GSE-Reactive, so im not too worried.

Do you think you can give me instructions on how to wire a modern PSU to the apple IIe. I'm getting another apple IIe PSU but it won't come for another 2 weeks.

sure its pretty easy, but very ghetto, (ie: electric tape)
requirements:
1. ATX standard PSU (btw: some dell power supplys are non-standard pinouts but use ATX plugs, do a google search to findout if you have a diffrent powersupply as connecting the wrong voltages to your II could cause damage)
2. Apple II power plug, (i took mine out of a busted PSU)
3. the diagram at hte bototm of this page : http://www.helpwithpcs.com/courses/power-supply-basics-inc-pinouts.htm
4. wire snips and stripper
5. electric tape

The Apple II power plug has 6 pins, 2 GND (ground) +12v, -12v, +5v and -5v

/---\
|1-2|
|3-4|
|5-6|
-----
this is probably not the standard pin numbering i'm just using it as MY guide to explain the pinouts. (hopefully it will not word wrap when i make this post) Pin 1 is top left corner when rounded end is oriented up, and pin 3 is directly below it, pin 6 is bottom left corner)

Pin 1: -12v
Pin 2: -5v
pin 3: +5v
Pin 4: +12v
Pin 5&6: GND

knowing this, you can see which wire plugs into each pin on the connector, and can match them up with the similar ATX pinout.

There is only one -5v and only one -12v connection on the ATX plug,
Blue and white, locate them on the diagram on this page(http://www.helpwithpcs.com/courses/power-supply-basics-inc-pinouts.htm)

you will need to locate and snip all the required voltages from the ATx connector, if you have trouble with this post again, its pretty straight forward

Along with the required voltages, find the PS_ON cable (green on standard atx i believe) and snip it, and snip a third ground cable.

so you should have -12v,+12v,+5,-5,GND,GND,GND, and PS_ON snipped from the PSU.

i recomend labeling these cables with some method (tape, sharpie etc so you know which is which)

Strip about half an inch off of each cable.

Strip about the same ammount off of the II Connector's wires.

Match each wire with this appropriate counterpart, +5 with +5 , gnd with gnd, and either solder them together, or wrap them together and cover with electric tape..

now we have the PSU attached to the II connector, but the PSU doesn't have anyway of knowing when to turn on. this is what the PS_On and the third GND are for.

Shorting the PS_on to the GND will cause the PSU to startup and supply voltage, but will only keep running while PS_on is shorted, you can wrap them together every time you want to turn on your II, or, I took the power switch out of the II's broken PSU, and attached to GND and PS_on and use it as an on Switch.

Plug the connector into your II, short the PS_ON, and hopefully you have all the cables connected correctly (double check) and you will get a startup!

good luck!
Ian

I have two questions. Does it really matter if -12 is connected to GND? Because I don't understand how you can get -12 volts. Also, when you said short the pwr_on, short it with what? And i use a 24 pin power connector, not a 20-pin

-12v does not connect to GND, the -12v from the Working PSU connects to the -12v lead on the II power connector,

PS_on shorts to the third ground, or any metal object such as the power suply case.

il look for a 24 pinout right now

http://pinouts.ru/Power/atx_v2_pinout.shtml

there is the 24 pinout sheet
see pins 14 and 20 are -5 and -12, those connect to pins 1 and 2 on the Apple II power diagram i drew above.
pins 5&6 on the II connector go to any 2 GNDS on the ATX
and +5 and +12 go to the many +12 and +5 pins on the ATX

hope that makes since.

My mod works! The wiring is different from diagram but I experimented. Thanks for the help.

good!
by different wiring, you mean the II connector, or the ATX?

The ATX was different from all the diagrams. But I figured it out.

yea i have made 2 of these, and my second one i realized i had a non-standard ATX pinout, it was a Dell PSU..

I think I'm giving a little too much voltage output. when I type, it types way too fast. Anything I can do to stop it?

get a volt meter and make sure you've got the right connections, its a switching PSU so ou have to have a load on it to measure voltage, so it will have to be running i belive, -12 should be top left on the Connector when you look at the pin side, wiht the rounded end on top, just to clarify the diagram
you can do damage by over powering the Mobo so double check!

Ian

I checked every pin. It seems that the -12v, or at least I thought it was -12v, is -9v. I don't have a -12v pin on my PSU. What should I do?

hmm i do not know, have you checked the pinouts on the smaller plugs to see if you can find a -12v, if you can't the PSU is really not fit to do what you want it to do... it may work, but supplying the wrong voltage for any long period of time, is bad and will cause damage.... so i don't knwo what to tell you...

None of the other pinouts have a -12v. I think my friend has a dead pc with a working PSU, I'll see if I can take his and use it.

Are you testing with or without a load on the lines? Without a load it may cause the voltage to vary.

I got my IIe PSU in the mail, works great. Thanks for all your help.