APPLEBOX 
 
 
    Apple Power Supply upgrading Story
 
Working with the computers of the Apple II series ( II+, //e or IIGS ) is usualy quite full with pleasure ... untill you start to enhance those systems with a couple of Interface- or expansioncards..... specially if you start to raise the amount of memory or if you start to eqip your computer with additional floppydrives or use coprocessorcards with additional memory ( unlike the simple "Softcard" with the Z80 Processor ) you will find out that the inside of the apple will slowly turn into a stove heating the entire area around the computer and you will also find out that the system turns to a rather instabil status - causing unpredictable crashes and freezes...

The normal reason for this is the unsatisfying problem of a weak powersupply in the applesystem. This problem is related to all computers throughout the entire series....
this is the result from the fact that in those days the market did not offer many chips for switching-power-supply-control and the powersupplies from those days where rather weak all together or like later with the arrival of the IBM PC the switching-power-suplies became rather "bulky" and waisted much space and needed large cases.

Years later the switching-power-supplies started to "shrink" dramatically and the power raised at the same time dramatically....

The first powersupplies for the IBM-systems provided a summary of 120 Watt the next generation offered 150 Watt and few years later the supplies commonly offered 250 to 350 Watt (summary-) power. Nowadays in the same cases powersupplies with 450 Watt to 550 Watt are usual. In the same time the cases of those powersupplies started to shrink in size and became smaller and smaller......

Some "slimline"-systems have realy tiny liitle switching-power-supplies in this days.....

So i for example started few years ago to collect the cases of old powersupplies from Apple II clones just to get an amount of cases for power-supplies that fit in the Apple III series computers..... i really didnīt bother if those supplies were working or not ... i just wanted the cases and the electronic inside the cases went to the recyclingyard.

At the same time i started - when visiting a electronic-shop - to keep an open eye for PC-powersupplies from small slimcase-systems and if some were offered with correct dimensions ( i.e. it would fit in one of those apple-power-supply-cases  ) i bought that supply and time by time i collected a cheap little amount of "fashionable" fitting supplies ( usually paying some $15 to $25 for that used supply.... sometimes you could get them by a visit at the recyclingyard for $5 bucks per unit....

Thereafter at home again i warmed up my solderingiron and did a small "heart-transplantation" by moving the interior electronics from the PC-supply into the case of the apple-power-supply-case from those collected apple-taiwan-clone computers.
 

 
To explain the difference of the power of such a supply after the "heart-transplantation" examine the table below:
( the applepowersupply offers 65 Watt while the LITEON-powersupply offers 200 Watt ! )

 
 
 
 

Applepo

wersupply

 

ATX Po

wersupply

 
  Voltage Power   Voltage Power  
  + 12 1,5 A   + 12 V 6 A  
  + 5 4 A   + 5 V 15 A  
  - 5 0,15 A   + 3,3 V 12 A ( unused )  
  - 12 0,15 A   - 5V 0,5 A  
        - 12 V 0,5 A  
             
 
 
here is a picture ( as example ) of such a PC-system slim-line-power-supply from LITEON with 200 Watt:

 
 

 
 
 

In this pictures both powersupplies are just set beside eachother to compare the dimensions of both powersupplies...... the LITEON-powersupply is 3 mm less high and the measure turns out with the same wideness. The LITEON-powersupply turns out to be 46mm less in the length than the applepowersupply and this permits to mount inside an additional fan. The second advantage of the powersupplies usually used in the taiwan-clones is that the engineers kept enough spacing in the case to make a good venting of the air possible. And dragging less power from the LITEON-powersupply ( normally i only drag about 140 Watt from that supply with a full loaded apple II system with 3 or 4 external floppydrives or with 2 floppies and a harddisk-system and also a 1 MB RAM card inside too and usually also a processorcard included ) that LITEON-powersupply wonīt get that hot like the one from apple.... because only 65% to 75% of the maximum from the limit is pulled out of the source.
 


The only tricky thing is the fact - that 2 cables must be connected internal - to make sure that the LITEON-powersupply gets switched "on" and "off" by the powerswitch on the backside and not by a "Power-button" like in the PC. The green cable from pin 14 an a black cable from pin 15 ( connected to ground ) must be short-cutted
( i.e. connected ) internaly.

 

 
  So after removing the electronics of the LITEON-power-supply out of its case i first equip the apple.power-supply-case with isolating plastic to make sure that there is no contact between the PCB of the power-supply to the powercase of the applesupply.  Before this is done there have been drilled the needed holes to fit the PCB in the applepowercase and the PCB is mounted using plastic-distance-holders to make sure that the PCB has a firm seating and remains without contact with the case of the supply itself.
Thereafter the cables of the ATX-powersupply-plug are carefully unsoldered and replaced with the according apple-powersupply-plug line by line. The colorsqares in the table of the ATX-table indicate the canlecolors !
see the drawing below !
 



Next the green cable from pin 14 and the black cable from pin 15 are shortened and soldered together and isolated carefully with shrinkingmaterial. Next step is to solder the switch between the one powerline of the plug-connector and the line to the PCB. The the remaining connection between the powerplug-connector and the PCB is soldered.

Finally connect for testing purpose a very old outdated harddisk with the powerlines +12 V, +5 V and Ground and switch the power on and measure with multimeter the  voltages at the plug.

If the voltages including also the - 5 V and -12 Volt are all O.K. - enjoy the new powersource for your apple II series computer - otherwise check and review all connections.
 

The picture below shows a modified powersupply:

 
   
 
 Added remark:

 Some people prefer to instead make an external Powersupply from large old PC powersupplies similar to the Buggie supply.
 In such cases nowadays it might happen, that that supply does not distribute the - 5 Volt power rail.
 In such cases itīs rather easy to drag the - 5 Volt out of the - 12 Volt rail by simply adding a small PCB with a 7905 negativ power
 regulation IC. That ICīs are distributed with different strengths. Itīs recommended to use a 1 Ampere typ or stronger. That IC should
 be supported by a small heatsink that might handle at least 3 Watt powerdisaption.
 The rest of the ecplenation should be taken from the following picture: