power supply question

[bradhig]

Both power supplies that came with my 2600s died and I used a universal 1.5-12v 300ma power supply and my 2600 worked perfectly with it. Is it okay to keep using this power supply with my 2600s or such I buy a new one?

[7800]

I personally would buy a stock one. Some people sell rebuilt stock ones on ebay, or you can just get a used one that works. But ultimately, get in the habit of UNPLUGGING it after your done using the system... this goes with any old game system.

[bradhig]

I personally would buy a stock one. Some people sell rebuilt stock ones on ebay, or you can just get a used one that works. But ultimately, get in the habit of UNPLUGGING it after your done using the system... this goes with any old game system.

I unplug them after use and even disconnect them from the tv. I could play 2600 games on my 7800 or on my modded colecovision with expansion module 1 ,but 7800 has a bad power switch and I have to disconnect ATT unverse from component connections to use Colecovision

[Osgeld]

power is power, theres nothing magical in those old stock ones, 7-9 volts dc is fine, lower the voltage, the better as all the 7805 regulator does is burn off the excess voltage as heat ,for instance (7 - 5) * 400 = 800mw, (9-5) * 400 = 1.6 watts. Most of those things have a 65c per watt so you can expect it to be around 77c in the first example (assuming the air around it is ~25c) and 125c in the second example (max is 175 it should start shutting off neat that)

 

course there's a heat sink which drastically complicates all of that, it probably runs hot as hell but fine on 12 volts

 

the original ones are 500ma, 300 is cutting it a bit short, on my bench my jr sucks 380ish, too much overload on a supply can cause a meltdown (on the supply side) so keep that in mind

Edited April 21, 2014 by Osgeld

[+Stephen Moss]

power is power, theres nothing magical in those old stock ones, 7-9 volts dc is fine, lower the voltage, the better as all the 7805 regulator does is burn off the excess voltage as heat ,for instance (7 - 5) * 400 = 800mw, (9-5) * 400 = 1.6 watts. Most of those things have a 65c per watt so you can expect it to be around 77c in the first example (assuming the air around it is ~25c) and 125c in the second example (max is 175 it should start shutting off neat that)

 

course there's a heat sink which drastically complicates all of that, it probably runs hot as hell but fine on 12 volts

 

the original ones are 500ma, 300 is cutting it a bit short, on my bench my jr sucks 380ish, too much overload on a supply can cause a meltdown (on the supply side) so keep that in mind

 

The statement that lower the voltage the better is only true to a point, yes a lower input voltage will result in less power dissipation in the 7805 however for these older non LDO versions in order for them to regulate their output voltage correctly the input voltage needs to be at least three volts higher then the output voltage therefore the minimum input voltage should be 8.

 

Any non original replacement PSU should match the specs of the original in terms of output voltage current and polarity if it is an unregulated supply, if it is a regulated supply more current is acceptable but voltage and polarity must match otherwise excessive heat and other losses in the PSU will occure.

[Osgeld]

datasheet on the lm7805 states 2 volt dropout at 1 amp for a non LDO, some of the ldo's are like 350mv drop or lower

Edited April 22, 2014 by Osgeld

[Atari-Collector]

As much as it's nice to have original parts, I won't bother with getting a original power supply for it. That would be a 30 year old unit, the capacitor inside could be weak, or other issues from it's age.

 

When I got my 2600 Jr there was no power supply with it, so I bought a brand new 9 volt Motorola unit and changed the plug, works perfectly.

 

I won't buy ones those super cheap ones from China on eBay though. Most are not approved for use in Canada or the USA and the quality is questionable at best. (yes I have tried them..)