Wednesday, June 8, 2011

Power Supply - Conversion

Being without a power supply got me searching for alternate power solutions. The original 230V power supplies are quite hard to come by and fixing the existing aging ones is only going to get me so far. Even when I get around to fixing them how much longer are they really going to last? What I was after was a long term solution. I have seen several good examples of converting PC supplies or triple voltage supplies but these require a modification to make them output the -5V voltage. That is not a huge issue but it is more work than I had hoped for. Quad voltage power supplies are also available but they are wider than the IIGS power supply (which is long and thin) making them difficult to fit inside the IIGS. That was until now. While searching around I came across the SDS60. It's a quad voltage power supply but has a form factor that will allow it to fit inside a IIGS power supply case.

When I ordered the SDS60 I was informed that full production of these was not yet under way so I had to wait a few months for the next run. It was a long wait but well worth it. Once I had the unit it took less than an hour to do the conversion and have my IIGS up and running again. It was the easiest soldering job I have done in years. What more could I ask for? Quad voltage power supply that is small enough to fit into a IIGS power supply case, a breeze to install and uses off the shelf parts. Perfect. It even has a wide input voltage range so you could easily transport it between countries.

Other power supply conversions :-

Made by XP Power
1. SDS60UQ02 Quad Voltage Power Supply
2. SDS60Q CONKIT Quad Voltage Power Supply Connection Kit

Australian distributors :-
1. (about AUD$150 delivered)

In my junk box I had a 120V IIGS power supply which I was going to convert into a 230V supply one day. This will work very well as a base. I desoldered the PCB then just added the cable connectors. It was then only a matter of adding the standoffs and plugging in the SDS60.

Next step is to do some load tests and swap the standoffs from adhesive to screw type. This should lower the PCB and move the heat sink from sitting right up against the cable plug.

Update: 1st November 2012.

I was able to convert another Apple IIGS power supply very cheaply thanks to Mike who found a great source of these handy replacement modules.
It only cost me AUS$45 for two modules including postage to Australia.

Jameco Part no. 2081721
Manufacturer EOS POWER USA INC.
Manufacturer no. LFMVLT80-4000

Mike's power supply conversion :-

Jason's power supply conversion :-

Other interesting power supply write ups :-

The procedure was pretty much the same as my other power supply conversion.

Tuesday, June 7, 2011

Power Supply - Failure

My IIGS has been running without a hitch for the past few years. I should have known better than to have left the twenty five year old machine running unattended while going outside to do some yard work. In the half hour that I was outside the power supply had failed and produced an awful mess. The room took weeks to air out. The peripheral cards, motherboard and monitor still smell of smoke and the case now has a nice brown burn mark on top. I took the power supply apart and just stood there for a while thinking, “What a mess! Am I every going to get the urge to clean that up?”

I thought I had done well by having a spare IIGS machine which I use for testing my electronic projects. When it came to turning it on all I got was the power light flicking on and off every half second or so. Frying two power supplies in one week didn’t impress me very much. I took this power supply apart and found that a large capacitor had blown it's top. However replacing the capacitor has not fixed the problem. The same symptom still persists. More load testing needed I think.

I intend on getting the power supplies fixed but sadly my trust in old hardware will never be the same again.

Update: 7th September 2017.

During OzKfest 2017 my machine let out the magic smoke. It would have been less to clean up if someone had pulled the power cord out, instead of watching and taking photos of the power supply spark and bellow out the smoke. But then again we managed to get this great photo. Turning off the power supply in this case did not work because this older unit had the line capacitor attached across the power plug and not to the supply circuit board.