Apple IIGS PSU from 110V to 220V

protek

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My Apple IIGS has been purchased from the US and the PSU is 110V only, so I have to use a step down converter. I don't find this solution very elegant, therefore a new PSU was needed. Apple IIGS euro PSUs don't grow on every tree, so I decided to change the innards of the orignal PSU.

The IIGS PSU outputs four different voltages: +5, +12, -5 and -12 Volts. I got a Mean Well PT65B, which outputs three of the four voltages. Luckily, the missing -5V can be achieved with a simple regulator circuit. I got the schematics for the circuit from a blog by a fellow named Drew Biegs, who had made this mod originally. Below is the regulator circuit:
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The PSU comes off pretty easily. Detaching the power cable from the motherbard was the hardest part. The lid comes off by unscrewing a few screws and the PSU is fastened by a couple of others. Here's the old PSU with the replacement.
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I got some Molex connectors and terminals for the job. I'm currently waiting a Molex terminal crimper to arrive. More to follow once the crimping tool arrives.
 

nivalis

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Interesting, I have been thinking about getting a 2gs from us myself, I would do something like this too in that case. Waiting eagerly for more :)
 

protek

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A little update. I attached the molex terminals to the wires. The molex crimp tool is so good that I can't understand how I possibly could have survived without.
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I also moved one of the screw posts to a new location. I still need some PCB feet.
Edited_ImageEasyImageEditor_20150131_102.jpg
 
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protek

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The new PSU is now in the casing. I used self adhesive plastic feet and one screw to secure the PSU inside the casing.
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I also tried powering it up for the first time. No magic smoke so far. :) Quick measurement with multimeter showed correct voltages in correct pins.

Still need to put the PSU case together and fit it back inside the Apple IIGS.
 
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protek

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I reassembled the PSU yesterday. Externally, it's indistinguishable from an unmodified one, with the exception of the "240V" label. Don't really know, why I put that value as it's actually rated for 230 Volts. Oh well.
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Then the moment of truth. Yay! Boots and works normally. :D When the GSOS is fully loaded, the system apparently puts more load on the PSU as it starts making a very faint humm, which can't be heard, when the OS is loading. Otherwise, no issues. The output ratings of the new PSU are sufficient at least.
Edited_ImageEasyImageEditor_20150203_109.jpg

Overall, I'm very happy with the overcome. That's one brick less under the floor as I can now remove the step down converter.
 
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protek

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Not happy with the buzzing caused by the 7905 regulator to provide the -5V, I decided to restore the PSU back to original condition and do the jumper wire removal hack to convert it to 220V. Luckily I still had the original parts available, so the restoration was pretty straightforward. After checking the connections with reference pictures and cutting the jumper wire, it was time to fire it up. No snaps, crackles, pops or blue smoke. I had naturally not yet connected it to the IIGS. I tested the voltages to be correct and happy with that I reassembled my IIGS. Works nicely as you can see from the picture and no more buzzing. :D

Photo 28.11.2016 20.37.43.jpg
 

Andreaux

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Reference pictures and PSU mod for the IIGS monitor?

Reference pictures and PSU mod for the IIGS monitor?

Not happy with the buzzing caused by the 7905 regulator to provide the -5V, I decided to restore the PSU back to original condition and do the jumper wire removal hack to convert it to 220V. Luckily I still had the original parts available, so the restoration was pretty straightforward. After checking the connections with reference pictures and cutting the jumper wire, it was time to fire it up. No snaps, crackles, pops or blue smoke. I had naturally not yet connected it to the IIGS. I tested the voltages to be correct and happy with that I reassembled my IIGS. Works nicely as you can see from the picture and no more buzzing. :D

View attachment 115166

Hi there,

How could I put my hands on those reference pictures and know what jumper wire to cut??

I also have a 110V PSU that needs conversion.

Also, does anybody now of such a mod for the IIGS monitor? It is also 110V and I don't remember having seen a swich to change that easily...

Thanks,

Gabriel
 

protek

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http://www.applefritter.com/?q=content/apple-iigs-psu-110v-220v#comment-81639

Here, and the preceeding thread is all you need to know. In my case one of the filter capacitors that are marked C1 and C2 actually blew later on, so you might want to either remove or swap those with higher rating. I’ve not changed the transistor Q1 so far but you might want to check it while you have the PSU open.
 
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