7800 power supply problem.

[bradhig1]

My 7800 won't power on and I think the power supply died. It wouldn't be the first time. The original power supply died and I got another off ebay. Is there anyway to fix th power supply? I don't wanna buy another and have it break as well.

[SignGuy81]

Depends on what the problem is with it really if it is worth fixing or not. Could just be a bad solder joint never know till you get it apart. Is it an old one that you got off ebay or a brand new one that is lighter than original?

[bradhig1]

It's an old one.

[bradhig1]

Just checked the power supply with my voltmeter. It's dead no current coming from it.

[SignGuy81]

If you can get it apart look for broken solder joints, and check diodes and see what cap looks like. Could be cracked solder joint, could be open winding in transformer, could be an open diode or shorted diode which may have caused winding to blow open in transformer, I doubt it is a problem with the cap because you would still see some voltage on the output.

[bradhig1]

Is there a better one I can buy that will last?

[+Stephen Moss]

Just checked the power supply with my voltmeter. It's dead no current coming from it.

 

I think you mean voltage, not current.

The problem could just be a bad cable, particularly if you always put your system away after use and wind up the cable the same way as you eventually get fatigue breaks in the cable. There are two ways of confirming if that is the case, flex the cable and see if the voltage returns for a split second or take the unit apart and measure the voltage where the cable is attached.

 

If there is no voltage from inside the unit where the cable is attached probably best to throw it away, but if you really want to fix it before checking diodes check the AC voltage output from the transformer (should be about 9V), if you are not getting that then definitely throw it away as a new transformer will cost you at least as much if not more than a power power unit.

[edladdin]

Is there a better one I can buy that will last?

 

If you are frisky with a soldering iron its a pretty easy business to replace the weirdo jack with a modern inside-tip barrel jack, and then 9 volt power supplies are less than $10. Or, cut the weirdo tip off your dead power supply and attach it in place of the barrel plug on the new adapter. Just make sure you get the polarity correct!

 

Power supply:

http://tinyurl.com/y95vbruu

 

Jack:

http://tinyurl.com/y8x7q4yy

[+-^CrossBow^-]

 

If you are frisky with a soldering iron its a pretty easy business to replace the weirdo jack with a modern inside-tip barrel jack, and then 9 volt power supplies are less than $10. Or, cut the weirdo tip off your dead power supply and attach it in place of the barrel plug on the new adapter. Just make sure you get the polarity correct!

 

Power supply:

http://tinyurl.com/y95vbruu

 

Jack:

http://tinyurl.com/y8x7q4yy

 

 

Posted this in another thread about these but this is the route I would take to sorta replace the original power jack on the 7800 with something more universal.

 

https://console5.com/store/nes-genesis-1-sega-cd-tg16-jaguar-more-female-jack-w-pigtail.html

 

I've purchased a few of these and have them on hand, but as yet haven't had a reason to actually them in anything yet. But I did do something similar like 15 years ago on a 7800 that a friend of mine sent me and didn't want or have the actual 7800 power supply for it.

[edladdin]

 

 

Posted this in another thread about these but this is the route I would take to sorta replace the original power jack on the 7800 with something more universal.

 

https://console5.com/store/nes-genesis-1-sega-cd-tg16-jaguar-more-female-jack-w-pigtail.html

 

I've purchased a few of these and have them on hand, but as yet haven't had a reason to actually them in anything yet. But I did do something similar like 15 years ago on a 7800 that a friend of mine sent me and didn't want or have the actual 7800 power supply for it.

 

Yeah, my 7800s (one personal and two in the shop) are all still running on original power supplies, but first time one of those dies, its getting the new jack so we can use "off the shelf" power supplies. The panel mount one will require modifying the old hole or drilling a new 5/16" hole in the back of the console, but that's not big deal unless you want to keep it in pristine condition for some reason.

 

Plastic drilling tip: start with a smaller pilot hole and then widen the hole with a couple of slightly larger bits. Keep pressure light and speed slow.

[bradhig1]

wiggled the cable and it works now. Something wrong with the cable.

[+Stephen Moss]

It is possible to find the exact point of the break but it requires two people, one to read and ensure a good connection to a multimeter, the other to hold one part of the cable steady and flex the rest. Work in halves, i.e. start holding the middle of the cable and flex each half to identify which half has the problem, then hold that half in the center and repeat, and so in unitl you idenitfy where the break is.

 

If the break is not too near to the connector you can either cut the cable an inch either side of where the suspected break is and solder it back together or if the point of the break leaves the cable sufficiently long enought to use just cut it an inch closer to the connector end and solder it to the original attachment point within the power unit - just make sure to get the polarity correct, side of cable with White/Grey/Red stripe should be positive.