My toshiba satellite a205-5804 has a problem with the main board, when its plug in it freezes but when not , when is used whith the battery it works alright. a repair center told me is the main board, but can it be repaired?

Actually your make and model of satellite was the worst of toshiba's recent production- the estimate was 16-18% have displayed what's called an intermitten i/o failure to the main board. (Input output of processing data to the mother or logic board that processes the overall functioning of the comp~ the brain of the comp). This has plagued Toshiba's production for the last 3-5 years, and 9-18% of units have been affected. The good news is: it's neither a logic board nor electrical failure! And the repair is both easy, a DYI repair for any novice, and super inexpensive (well in the grand scheme of comps). What will fix your laptop is new RAM. Your toshiba can seat up to 8gs and as little as 4g. It uses DDR3 RAM, paired. The ram sits in the main board and over sees the i/o of data, is a main part of the EFI (the firmware interface of your hardware), and is in charge of ensuring the electrical assembly circuit is complete. Cost of parts on Amazon (spring for new RAM) will run you $50-65, the repair is 3 screws, pop out old ram, pop in new, replace panel, screw back in 3 screws. It's the easiest possible repair you can do yourself, even listed in the owners manual. See links below. 1st is your ownwers manual, 2nd is to ifixit.com to your laptops ram replacement guide. I'm an A+ PC repair tech and an ACMT apple repair tech. I rarely recommend DIY, but this is cake. If you boot after and see 3 blinking lights, you didn't put the ram all the way in. good luck! Next time, buy a toshiba TV, but not a laptop.... :) http://www.manualowl.com/m/Toshiba/Satellite-L655-S5150/Manual/281632 http://www.ifixit.com/Guide/Installing+Toshiba+Satellite+M305D-S4829+Memory+%28RAM%29/5424/1

Toshiba satellite L300 is connectting adapter on turn off machine how problem?

It isn't receiving power. Try with another power adaptor.

If the laptop works fine with the battery but fails when the adapter is plugged , the there are transient voltages from the adapters SMPS. You will need to remove and check for failure of capacitors, possible the main tank capacitor is leaking or under value.
open and confirm but do not connect to laptop unless this is checked as you can damage the mother board.

How about this step, try to turn off the laptop itself. Remove the cables and battery just like what you did before, then press and hold the power button for 10 seconds. Then, reinsert the cables and battery on the laptop and then turn on the computer itself. If the laptop restarts, shuts down or freezes with the AC power cables, two things that you should seriously consider. It might be the power cable itself, AC cable port or the circuitry going to the motherboard. And since you have cleaned out the fan and heat sink, you have isolated that problem. Have you plug-in another power cable on your laptop? If yes, then check if it works. Otherwise, the main issue is that the AC port is loose or the circuitry of AC adapter going to the motherboard is not not working. You can re-open the unit and check the circuitry from the AC port going to the motherboard. You may check the circuitry from AC port to the power supply if it is ok. If symptom persist, please contact your local dealer...

It sounds like the connector from the A/C adapter to the motherboard is loose or the inside of the adapter plug that attaches to the motherboard is defective.

A couple of possibilities:

1) The power jack on the main board needs to be resoldered. Sometimes the connections break at the circuit board because of power plug flexing. This is not a difficult repair, but it means taking the main board out so you can reach the solder side (bottom) of the board. In some cases the main board can be damaged because of heating and arcing at the bad connections, and occasionally the damage is serious enough that the board needs to be replaced.

2) The main board in the computer has failed. Almost all of the electronics in a laptop is on one big circuit board, and when it fails, a "no boot" condition is a very common result.

If you don't feel comfortable taking out all the screws and covers to get the board out to try your own repair, I would suggest getting an estimate from a servicer. The shop I used to work for charged a little under $100 to repair the board if it was bad connections.

There is a video even posted about how to do it, I am sure that will be even better than text describing. A guy poured cola on his Toshiba Satellite A100 and had to clean the keyboard, for which he had to take it out. So here is the link:
http://www.youtube.com/watch?v=-TrTtNZcf44

If this helped, please rate me:)

with AC power cord plugged in
do a virus scan
in add/remove uninstall any programs you no longer use.
Do a windows update
then do a disk defrag
please let me know if this has solved

Bad battery connector on your motherboard