Atari AC Adapter Output Voltage

[Banquo]

I have two Atari 2600 AC adapters here which are rated to output 9v DC, however they are both going quite a bit over that.

 

CO10472 14.6 V

C016353 15.2 V

 

I know the 7805 regulator can handle even more than that but that's just more heat, I'm curious why these adapters are putting out way higher than 9 volts, are they going bad or is this just how they were? Should I replace them with a modern 9v power supply? I want my 2600 to live a long and happy life.

[Umberto]

Normal, test while plugged in to 2600

Edited February 16, 2019 by Umberto

[Banquo]

Thanks, just wanted to make sure they were ok and not end up frying the console someday if they failed.

[+Stephen Moss]

I know the 7805 regulator can handle even more than that but that's just more heat, I'm curious why these adapters are putting out way higher than 9 volts, are they going bad or is this just how they were?

Generally I would expect more 12-13v but it depends on the transformer, much higher than 15 would be a concern.

To save money on components they use a transformer that can output less current that required by the console but at a higher voltage (P= V x I so less I means more V), when connected to the unit more current it taken from the transformer than it was designed to supply, consequently as the output power (P) of the transformer is fixed V is exchanged for I and the output voltage drops in proportion to the extra current being drawn and subsequently you get around 9-10V going in when the console is on and drawing power.

It is standard design/practice on cheap unregulated/unstablised power supplies. The down side is that the VI losses involved in such an exchange manifest themselves as heat with is why the power unit gets quite warm during use.