repro 2600 power supply, modded for 7800?

[J.Ivy]

So i found reproduction atari 2600 power supplies on ebay for only 7 bucks. I was thinking of scrapping my old 7800 power supply and replacing it with this modern one. They both output 9vdc and 1 amp and id only need to add a 3.5mm jack to the back of my 7800.

 

My 7800 power supply has a brittle cord and is now taped up, so rather than add a new cord to it, i figured using a power supply with a standard jack would be beneficial.

 

Is there anything that im missing, or not seeing to make this mod work?

 

http://www.ebay.com/itm/US-9V-1A-Power-Supply-Adapter-Charger-Audio-3-5mm-Jack-Same-Day-Shipping-From-US/350912770823?_trksid=p2047675.c100005.m1851&_trkparms=aid%3D222007%26algo%3DSIC.MBE%26ao%3D1%26asc%3D23423%26meid%3D7712509397993883972%26pid%3D100005%26prg%3D10050%26rk%3D1%26rkt%3D6%26sd%3D370930190981&rt=nc

[gilsaluki]

Got one. I use it on my 7800. Works fantastic. Lightweight to boot.

[J.Ivy]

Got one. I use it on my 7800. Works fantastic. Lightweight to boot.

 

Great to here. I just bought one and a jack. Should have this atari modded by the end of the month.

[fiddlepaddle]

Might also consider replacing the new 2600 connector with the 7800 connector from your old power supply. That way if you decide to/need to replace your 7800, no new mod is necessary.

[+Mitch]

Mini jacks are a bad idea for power jacks. Get one of the repro 7800 power supplies if you need a new one.

 

Mitch

[thecrypticodor]

If your gonna add a jack than I would suggest using a 5.5mm x 2.1mm power barrel jack. Which is the most common power supply jack there is and if you wire the center pin as negative you can use Master System, Genesis Model 1, and Atari Jaguar Power supplies.

 

http://www.ebay.com/itm/5-5-mm-x-2-1mm-DC-Power-Jack-Socket-Female-Panel-Mount-Connector-TR-/181293245635?pt=US_Surveillance_Cables_Adapters_Connectors&hash=item2a35eb64c3

 

This is the route I took and it's much cheaper more convenient and you won't have to stay a slave to that stupid propitiatory connector.

Edited June 19, 2014 by thecrypticodor

[J.Ivy]

Well i already picked up a domed 3.5mm jack, the repro 2600 power supply and a male to female extension cord for it.

 

3.5mm is pretty standard, so even if this power supply does go out one day in the far future, it wont be an issue to mod another to use that jack. Im not about keeping my 7800 stock, im about keeping it functioning and adding possible non invasive improvements.

[Andromeda Stardust]

IMO the original stock Atari adapters have very brittle wires. My original Atari adapter wire broke off inside, then I spliced the tip to an old Lynx adapter, which later broke as well. I then made a 9V frankendapter with a 9V Radio Shack brick spliced together with three tips, a tip negative barrel for NES/AV Famicom/Genesis/TG-16, a tip positive inverted barrel for SNES, and a tip positive stereo minijack (harvested from a headphone patch cable with the center ring / red wire grounded) for Atari.

 

3.5mm or 1/8 jacks are super common. You can even use a stereo minijack if you can't find a mono one. Tip/left/white is positive; the bottom ring/black or bare wire is ground. The middle sleeve/right/red wire can either stay disconnected or bridged to ground. IMO I don't think it really matters if the tip is round or pointy.

 

Watch out for 3rd party console replacement adapters. Many are unregulated and often putout too much juice, like 13-14V instead of the 9V that's on the face plate. Those extra volts get converted into waste heat by the 5V regulator and there's no need to run the regulator cip hotter than it needs to be. 7-11 volts 1A is ideal. 12V or more is a little much for retro consoles.

[J.Ivy]

Okay, so the 2600 power supply has arrived. I drilled and installed a 3.5mm jack. I found out what the negative and positive sides are from the transformer but..

I forgot to check the original power supply (before tossing it) for which was neg and which was the pos side.

 

When you look at the atari from the back, which side of the plug is which?

 

Sorry, i made a stupid mistake and forgot to check.

 

[J.Ivy]

okay..i screwed up, the power terminals for the o.e power supply, they were loosened by me removing the original jack. i wired them to the new 3.5mm jack and..nothing, even when i switched polarity.

 

so.. perhaps these two motherboard power lugs, now being loose, are disconnected. Ive seen a few 7800s that were modded for new power supplies, where they attached wires to a different area of the board to power it. Can anyone show me exactly where they are?

[J.Ivy]

sorry, double posted

Edited June 24, 2014 by J.Ivy

[thecrypticodor]

 

Just follow the traces from where the pins of the connector are. If you had the polarity reversed even for a split second there is a good chance you destroyed that 2200uf capacitor.

[themushroom]

The way I mod 7800s -- and made it into the CAGS.FAQ in the 90s for doing so -- is like J.Ivy's except I leave the 7800 connector intact, wire inline by the big cap, and put the mono jack in the 'strut' (an inch to the left of where it is in J.Ivy's photo).

 

I've never had a problem using a standard 9VDC 500mA Atari wallwart (7800 stock is 1000mA), and have never owned a real 7800 PS.

[ApolloBoy]

Many are unregulated and often putout too much juice, like 13-14V instead of the 9V that's on the face plate.

The reason why they put out 13-14V instead of 9V is because that's what the voltage output is like without a load on it. Once you add a load to it (i.e. connecting it to the console and turning the power on), the output drops down around to 9-10V.

[Andromeda Stardust]

The reason why they put out 13-14V instead of 9V is because that's what the voltage output is like without a load on it. Once you add a load to it (i.e. connecting it to the console and turning the power on), the output drops down around to 9-10V.

Nope, cheap electronics. My Radio Shack 9V "frankendapter" adapter puts out 10V unloaded.

[ApolloBoy]

Nope, cheap electronics. My Radio Shack 9V "frankendapter" adapter puts out 10V unloaded.

That's because those particular Radio Shack PSUs are regulated. If you measure an original PSU for say, a 2600 or Genesis, it'll be several volts above what it says because it's unregulated. Again, once you put an unregulated PSU under load, you'll get close to the voltage that's labeled on it.

[Andromeda Stardust]

That's because those particular Radio Shack PSUs are regulated. If you measure an original PSU for say, a 2600 or Genesis, it'll be several volts above what it says because it's unregulated. Again, once you put an unregulated PSU under load, you'll get close to the voltage that's labeled on it.

And a couple years back, I bought a Yobo Adapter "univeral" 3-in-1 NES/SNES/Genesis adapter, and it was rated 9V on the plate. 14.9V unloaded, but still between 12-13V under "load". IMO, that's too much juice for the 25-year-old regulator IC to handle. I'm not gonna needlessly stress my console like that. I ended up trashing the cheap junk Yobo adapter, and harvested the tips to biuld my 5-in-1 "frankendapter". For the Atari, I cut a stereo mini plug off the end of a headphone cable. No more unregulated power supplies that provide too much juice.

 

Occasionally I also use an old Bell Telephone adapter that outputs 9V AC (9.6V on my multimeter) to use with my NES. Say what you want, but I don't trust unregulated power supplies unless I test them first. There are good ones that only go a volt or two over rated unloaded, and some crappy ones that are nearly twice what the face plate says. Use whatever you want, but better to be safe than sorry.

 

Repairing the voltage circuit on an old console can be done but is a PITA, worse if you don't know how to fix it and end up trashing and otherwise good console.

[ApolloBoy]

Say what you want, but I don't trust unregulated power supplies unless I test them first.

...I never said they were any better or anything along those lines. In fact I use a PS2 slim PSU (which is regulated) along with a homemade tip adapter for most of my consoles.

[Andromeda Stardust]

...I never said they were any better or anything along those lines. In fact I use a PS2 slim PSU (which is regulated) along with a homemade tip adapter for most of my consoles.

Dude, I just checked the specs and that thing has like enough amps to power like all my retro consoles simultaneously!

 

It would be an excellent solution to someone who displays all their consoles in a little row. Just run lengths of wire to the appropriate tips for each console and lable accordingly. Assuming they've got some type of master A/V or RF switchbox, they'd never have to unplug anything, well save for carts and controllers... ;p