|The old Doepfer power supply with a|
The newer version is a better version, more reliable and provides a steadier voltage that is better for your system, although i personally never heard any complaints about the old transformer besides the longer warming-up time.
The old power supply has a black or blue rectangular transformer, where the new power supplies have a round silver transformer.
|The new Doepfer power supply with a round transformer|
In any case all A-100 cases manufactured later than early 2005 are equipped with the new power supply, and all cases manufactured until about of 2002 are equipped with the old version.
For cases manufactured in 2003 and 2004 it depends which version has been ordered by the customer.
It says "Power Supply II" unless it was removed by the user.
Source: Dieter Doepfer