New Amiga 1200/500 Power Supply

12v and 5v PSU

My A500 is about 30 years old now and although the old PSU appears to work its life cannot continue forever. My main concern is the failure of the old PSU resulting in bad voltages going to the old computer. This is certainly a problem for C64 power bricks and isn't worth the risk.

Mean Well make the RT-65B which can supply up to 5A on the 5V rail which is more than needed. The original PSU isn't great when expanding the computer with new peripherals such as accelerators or USB ports. 

Jan Beta and Ms Mad Lemon have both covered Mean Well PSUs and this is what I've done here myself. I've actually used the same case as Ms Mad Lemon due to the good fit. Jan Beta used the old PSU case, but I didn't want to destroy the original here.

I must note that doing anything with mains power supply is extremely dangerous even when using an assembled power supply. Doing any kind of assembly like this is at your own risk. There are many good replacement power supplies for the Amiga available to purchase. One example is Electroware who I used to source the 5 pin connector.

Parts

PSU parts

Power supply case is from e-bay and is a good size to snugly fit the Mean Well and wiring. 

Kettle connector is from e-bay (loads of choice on e-bay, can't recall the vendor). I decided to go for a kettle style connector to protect against pulling of the mains cable which could detach the live wiring inside the case. 

I decided to go to Mouser for the Mean Well PSU and also got the illuminated power switch from Mouser. The switch isolates live and neutral wires whilst also providing a neon bulb.

Finally I bought the 5 pin power connector from Electroware in Poland. Again this was through e-bay. This is a new and good quality connector. Easy to solder and assemble. 

Assembly

The switch and kettle connector require a bit of depth in the case. I also connected up with crimped connectors instead of directly soldering in wires, which requires more room.

There was just enough room to safely have the switch and power connector at the front of the case. Measuring out the required cutouts was simple and a Dremel did the cutting. 

A 15A solid core mains cable was used to internally connect the live parts over to the PSU inputs. 

Internal connections for mains voltage

Assembled power connectors

5 core car loom wiring was used to connect out to the Amiga 5 pin connector

Soldered 5 pin power connector for Amiga

The original power brick helpfully provides a diagram of the pin layout going to the Amiga. 

Final adjustment

Voltage can be adjusted on the Mean Well by turning the potentiometer on the supply case. Reading the 5V pin directly, without load, should be a little over 5V to accommodate for a drop under load.

It's important to check the voltage when under actual load. For an accelerated system this will vary depending on the type of card and other expansions. The voltage under load can be read by connecting to the 5V and GND pins of the Amiga floppy drive port.

Connected PSU

I think the replacement PSU looks quite smart and can be tucked away very much like the old supply. It should give more life to my old Amiga 500 as well as providing more reliability to my accelerated 1200.