Toshiba C850 only wants AC power

[sparker1]

I have two of these and they have the same problem. If the battery is present and the laptop started on AC power it will go to a black (Backlit) screen with a fixed cursor, the numlock will light and then the screen will go black, as if it is going to go to the OS, but then goes back to the unblinking cursor with lighted numlock. It repeats this cycle. However, if the battery is removed and just the AC power is used the laptop boots fine. Some other information: The charge light comes on, as if the battery is being charged when the laptop is turned off with AC power in. At this stage I don't know if it is really charging the battery. How can I check this? Any ideas where I might start looking? Is there a schematic out there?

This is just a hobby and I don't have much in the way of experience or knowledge but I appreciate any help.

[spidey]

Re: Toshiba C850 only wants AC power

seems like nec/tocin issue.

[sparker1]

Re: Toshiba C850 only wants AC power

Thanks Spidey, I have done a successful repair of a different Toshiba with a nec/tokin issue.Thanks to the info on this site. However, these don't have the big capacitor that is involved in those repairs. As an update there is no voltage output from the battery terminals of the motherboard. Strange that it works without a battery.

[Tuomo]

Re: Toshiba C850 only wants AC power

I have two of these and they have the same problem. If the battery is present and the laptop started on AC power it will go to a black (Backlit) screen with a fixed cursor, the numlock will light and then the screen will go black, as if it is going to go to the OS, but then goes back to the unblinking cursor with lighted numlock. It repeats this cycle. However, if the battery is removed and just the AC power is used the laptop boots fine. Some other information: The charge light comes on, as if the battery is being charged when the laptop is turned off with AC power in. At this stage I don't know if it is really charging the battery. How can I check this? Any ideas where I might start looking? Is there a schematic out there?

This is just a hobby and I don't have much in the way of experience or knowledge but I appreciate any help.

Looks like Battery control mosfet is OPEN all time?

[sparker1]

Re: Toshiba C850 only wants AC power

Looks like Battery control mosfet is OPEN all time?

Thanks. I thought it might be something like that. I tried to find a schematic but no luck. Even the guy on ebay didn't have it. I think the best bet would be to check the mosfets around the battery compartment area, I guess. Again, thanks to this site I now have an idea how to check them. I think I'll post a photo of the area of the motherboard when I get home.

[spidey]

Re: Toshiba C850 only wants AC power

Thanks Spidey, I have done a successful repair of a different Toshiba with a nec/tokin issue.Thanks to the info on this site. However, these don't have the big capacitor that is involved in those repairs. As an update there is no voltage output from the battery terminals of the motherboard. Strange that it works without a battery.

it seems like protection circuit error, it is in charging circuit.Need to check shematic.

[sparker1]

Re: Toshiba C850 only wants AC power

it seems like protection circuit error, it is in charging circuit.Need to check shematic.

Lol, if only I had one.

[sparker1]

Re: Toshiba C850 only wants AC power

I apologise for the photo quality. My camera was stolen and I haven't got a replacement yet. I have checked the two mosfets in the vicinty of the battery/power area and they checked OK. I did find an SMD ceramic capacitor that is open circuit and fails my ESR meter test (ringed in red). I am going to replace it but I don't know it's value. I could take a punt and use one from another board of the same physical size and appearance but I don't know how fussy the circuit is. alternatively, I could try and find one the same physical size and characteristics as the other ones on this board, assuming that this one is also of that value or should I just use the highest value SMD cap I can find that is the same physical size?

[sparker1]

Re: Toshiba C850 only wants AC power

I replaced the capacitor and another one I suspected but it made no difference. There is another IC I am concerned with. It's possible that it is involved in the charging circuit but it has only got the the symbols of
0151
G991
It looks like an 8 legged mosfet and has an indentation on it for pin 1.
That's the only ID on it. Does anybody know what it is or how I can identify it?
Here is another awful mobile phone photo [/URL] Uploaded with *************[/IMG]

[sparker1]

Re: Toshiba C850 only wants AC power

The reason I suspect this IC is that the source pins are open circuit - if it is a mosfet

[sparker1]

Re: Toshiba C850 only wants AC power

The reason I suspect this IC is that the source pins are open circuit - if it is a mosfet

I found it here http://www.gmt.com.tw/product/datasheet/EDS-991.pdf
It's a linear fan driver. I guess it drives the fan (brilliant!). Nothing to do with the charging circuit so the search goes on.

[Tuomo]

Re: Toshiba C850 only wants AC power

I found it here http://www.gmt.com.tw/product/datasheet/EDS-991.pdf
It's a linear fan driver. I guess it drives the fan (brilliant!). Nothing to do with the charging circuit so the search goes on.

Do it works just battery not AC inserted?

[spidey]

Re: Toshiba C850 only wants AC power

can you give me te mobo code ? with a schematic we can move on..

[sparker1]

Re: Toshiba C850 only wants AC power

Do it works just battery not AC inserted?

It's a good question. However, I have 2 batteries and both are flat. Neither laptop will charge a battery.

[sparker1]

Re: Toshiba C850 only wants AC power

can you give me te mobo code ? with a schematic we can move on..

Spidey, I really hope you can help with a schematic. I think the code is H000050950. Thanks.

[sparker1]

Re: Toshiba C850 only wants AC power

I haven't been able to get a schematic and with my level of knowledge it may not help a lot anyway. Since I had two of these with the same problem (neither will run with a battery inserted) I bought a new motherboard and I have compared the new working board to the broken ones around the battery area. The new board is revision 1.1 whilst the old ones are 2.1 and that is a complicating factor. Nevertheless I have found the component in the picture gives different readings on resistance (apologies if this is not set out properly).

Old IC-Identity on board 21/23 New Board identity C96MH

Pin1 to Pin 4 old board=infinity (i.e. 1 on DMM) new board=infinity
pin1 to pin 5 old board = infinity new board= 938 ohms
pin1 to pin 6 old board= infinity new board= infinity

pin2 to pin 4 old board = 910 new board= infinity
pin2 to pin 5 old board= 447 new board= 460
pin2 to pin 6 old board = 957 new board= infinity

pin3 to pin 4 old board = infinity new board= infinity
pin 3 to pin5 old board = infinity new board= 938
pin 3 to pin6 old board = infinity new board= infinity

The components look the same but have different markings. I don't know what they are and would like help identifying them. Finally, do the readings indicate a failure of the component on the old board or could it just be in a different state? What are these things??

[Tuomo]

Re: Toshiba C850 only wants AC power

I haven't been able to get a schematic and with my level of knowledge it may not help a lot anyway. Since I had two of these with the same problem (neither will run with a battery inserted) I bought a new motherboard and I have compared the new working board to the broken ones around the battery area. The new board is revision 1.1 whilst the old ones are 2.1 and that is a complicating factor. Nevertheless I have found the component in the picture gives different readings on resistance (apologies if this is not set out properly).

Old IC-Identity on board 21/23 New Board identity C96MH

Pin1 to Pin 4 old board=infinity (i.e. 1 on DMM) new board=infinity
pin1 to pin 5 old board = infinity new board= 938 ohms
pin1 to pin 6 old board= infinity new board= infinity

pin2 to pin 4 old board = 910 new board= infinity
pin2 to pin 5 old board= 447 new board= 460
pin2 to pin 6 old board = 957 new board= infinity

pin3 to pin 4 old board = infinity new board= infinity
pin 3 to pin5 old board = infinity new board= 938
pin 3 to pin6 old board = infinity new board= infinity

The components look the same but have different markings. I don't know what they are and would like help identifying them. Finally, do the readings indicate a failure of the component on the old board or could it just be in a different state? What are these things??

Remove Battery and measure Battery PINS on motherboard.

This way you see if AC voltages go to Battery.

[sparker1]

Re: Toshiba C850 only wants AC power

There is no voltage at the battery terminals

[Tuomo]

Re: Toshiba C850 only wants AC power

There is no voltage at the battery terminals

Not even 3.3V?

[sparker1]

Re: Toshiba C850 only wants AC power

I'll measure it again and get back.