Earlier this spring in 2019, I ran into a number of stability issues with my Amiga 2000. At that time, I was experiencing multiple problems during boot-up and general video display operations. My Amiga consistently kept crashing during my Picasso card initialization and Sunrize Cards and I had no idea why. After chatting with the folks on the Amiga forum, in particular, Damien @ Hypex , I decided to see if the problems were with my aging power supplies, on my Amiga 2000 and external SCSI Tower. From my early college electronic classes, I remembered the main reason for power supply failures, was due to high voltage and current surges demands. My Amiga was purchased in March 1989 and was operating with the original power supply. Over many years of use (30 years to be exact), my Amiga 2000 p/s and SCSI Tower was probably now experiencing multiple component failures from bridge rectifiers, diodes, and capacitors. After close inspections, I decided to replace the power supplies given their age.
The photos below indicate a sequence of events that resolved these issues. After a few weeks of replacing both my ATX P/S on my SCSI Tower and A2000, the Amiga was back online and was no longer struggling with video and sound stability issues.
I hope the photo’s below will provide additional information into my debugging activities.
Orginal 1989 Amiga 2000: The 1st Month
My initial research on power supply replacement led me to John’s “Chucky” Hertell excellent website (thank you Chucky !). At that time, I knew nothing about the ATX standard and Molex connectors:
“ATX (Advanced Technology eXtended) is a motherboard and power supply configuration specification developed by Intel in 1995 to improve on previous de facto standards like the AT design. It was the first major change in desktop computer enclosure, motherboard and power supply design in many years, improving standardization and interchangeability of parts. The specification defines the key mechanical dimensions, mounting point, I/O panel, power and connector interfaces between a computer case, a motherboard and a power supply “
Replacing the 2000 ATX power supply
You can purchase a replacement ATX unit from Amazon but you will need an ATX adapter for your Amiga motherboard.
Amiga ATX Adapter
Additional information about the ATX adapter was found on Ian’s website
+5V @ 20.50A
+12V @ 8.00A
-5V @ 0.30A
-12V @ 0.30A
Note: This system requires a ‘tick’ circuit which provides a 50/60Hz +/-10% reference signal to the video chipset or motherboard jumper J300.
Will require a simple linear regulator circuit using a 7905 or equivalent, to generate -5V