1) Check to make sure the problem isn't the cable going into the plug, from the AC adapter. (Charger)
A lot of times, where the wires meet the back of the plug, that goes into the laptop DC Power Jack, is bad.
The wires have a break from becoming stretched. Makes an intermittent contact.
Same thing for where the wires meet the charger body.
AC adapter plugged into power, unplugged from laptop, use a multimeter set to the DC voltage scale.
Use the alligator clip attachments for the probe leads, attach the probe lead's to the AC adapter's plug, and wiggle the wire, check for an intermittent break.
2) AC adapter (Charger) unplugged from laptop, Battery removed, see if you can wiggle the center pin of the jack.
You may find the entire DC Power Jack will move a little.
If the center pin does not move, but the entire body of the jack does, the jack may just need to be
resoldered to the motherboard. The solder connections may be cracked.
If the center pin moves, replace the jack.
To replace the DC Power Jack, or repair the solder connections,
1) Remove all power to the laptop. AC adapter and Battery.
2) Observe Anti-Static Precautions:
Buy and wear an ESD wrist strap. (Electro Static Discharge) Connect the alligator clip to a good ground source. I connect mine to the metal frame of an open, empty desktop computer case.
(You don't need an Anti-Static Mat)
The price of an ESD wrist strap is around $3 to $8. Found in a multitude of places.
3) Completely disassemble the laptop down to the bare motherboard in your hand.
No Processor, Heatsink assembly, peripherals, nada.
A) You may wish to take photos, or make a video as you disassemble, for your first time. Also make notes.
After the first laptop the next one becomes easier.
(All of them follow a basic path when disassembling. Toshiba, HP, Acer, Gateway, you name it)
B) Use a multi-container for the various screws. Label each container for the area the screws came out of.
There may be 60 or more screws, and 12 different types of screws. Some look VERY similar to each other, but are NOT. DO NOT mix them up.
You can use a clean egg container in a pinch. Label each egg holder.
C) Take your time, use patience. Practice your soldering, de-soldering skills before working on the Toshiba's DC Power Jack, if you're rusty.
Use Desoldering Braid, and not a Desoldering Tool. (Solder S-ucker) The desoldering braid works MUCH better! (Also known as solder wick)
Pictorial, with details on how to disassemble the Toshiba Satellite A70, or A75 series of laptops,http://www.irisvista.com/tech/laptops/ToshibaA75/satA75_1.htm
You can click on each photo to enlarge.
Page 2, and 3 icons are at the bottom.
(You are on Page 1.
Page 1::Page 2::Page 3 )
One source for a Toshiba Satellite A75-S209 DC Power Jack,http://www.laptopjacks.com/view_part/For-Toshiba-Satellite-A75-S209-DC-Power-Jack-TS51625.html
Toshiba Satellite A70 series Service Manual, (Free)http://www.tim.id.au/blog/tims-laptop-service-manuals/#toc-toshiba
Go down to the line that begins with Satellite A10.
Scroll across to A70, and click on it.
This is a PDF file. May take up to 30 seconds before you see the first page.
May take additional time to fully download.
(Took me around 40 seconds before I saw the first page, with a medium speed DSL connection)