Adapter LED flashing, laptop not switching on

[aaronmarsh632]

Hi,

I did reply to a previous thread but I thought I'd create a new 1 for my own problem and provide an image with it.

Basically if I plug the laptop charger in the LED on the charger flashes rapidly and the machine wont boot up. I have stripped the laptop and tried changing the jack but problem is still there. After reading the previous post it sounds like it could be something called the 'startup cap' I have taken a picture of the motherboard where the DC jack is connected and circled the part which I think is the 'startup cap'. Can anyone confirm if this is the correct part and if not can anyone help me with this problem please? Also how can I test the cap to see if it is faulty before replacing it?

Thanks

Aaron

[retiredcaps]

Re: Adapter LED flashing, laptop not switching on

The startup cap that they are refering to is inside the AC adapter and usually an electrolytic capacitor. It is not on your laptop motherboard.

[lord]

Re: Adapter LED flashing, laptop not switching on

Did you try another charger?

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Hi, yeh I tried another charger before stripping down the laptop. I have seen this lots of times and trying a new charger has never solved the problem for me atleast. I also changed the jack which hasnt fixed the issue, have you any suggestions as to what may be causing the problem?

thanks for your replies.

[lord]

Re: Adapter LED flashing, laptop not switching on

Measure the resistance between the + and the - on DC jack on the motherboard.

[xaviero1412]

Re: Adapter LED flashing, laptop not switching on

maybe, shorted bipolar caps

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Hi, thanks for the replies. I have tested the jack with a multimeter and its giving an output of average 2.5v (should be 19v in my case). Which would be the bipolar caps? I'm guessing the large cylinder cap between the battery connector and cpu?

thanks

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

EDIT: I think I may have found the problem, I left the charger plugged in for a few minutes and if I get close I can smell - not burning as such but smells like heated flux, then I noticed some bubbling from 1 of the (if im not mistaken) voltage regulators. Not the 1 I have marked blue, the 1 above it. On the top of the component is where I can see it bubbling where its soldered (not the pin side). I will have a look to see if I can get a replacement from ebay orsomewhere and once I replace it I will post results.

Thanks

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Sorry for the tripple post but im having trouble finding a replacement. The information I can get off the component is...

1H34SB
FDD
6685

Both those parts on the board are the same. I dont currently have ano other motherboards which I can transplant the parts from, and I cant find any information regards these on the net so I dont know what an equivalant alternative would be, can anyone offer any ideas please?

thanks again

[trebo]

Re: Adapter LED flashing, laptop not switching on

Sorry for the tripple post but im having trouble finding a replacement. The information I can get off the component is...

1H34SB
FDD
6685

Both those parts on the board are the same. I dont currently have ano other motherboards which I can transplant the parts from, and I cant find any information regards these on the net so I dont know what an equivalant alternative would be, can anyone offer any ideas please?

thanks again

Data sheet here
http://www.alldatasheet.com/datashee...D/FDD6685.html
there are plenty of replacments on Ebay found here
http://www.ebay.co.uk/sch/i.html?_tr...+6685&_sacat=0

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Hi, thanks for that, I have been searching for the top number - i assumed the others were revision numbers etc so didnt use them. Thanks for that.

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Hi, I finally got the new parts this morning and soldered them on, unfortunatly I still get the same problem - does anyone know what could be causing this please?

thanks

[ben7]

Re: Adapter LED flashing, laptop not switching on

Something must be shorting out the Vreg, burning it up. Desolder it and see if there is a short on the output (on the board, not the regulator).

[budm]

Re: Adapter LED flashing, laptop not switching on

That device is a MOSFET, you should remove it and then take the resistance reading between the chassis and one pad at a time, report the resistance reading on all 3 pads.

[ben7]

Re: Adapter LED flashing, laptop not switching on

...you should remove it and then take the resistance reading between the chassis and one pad at a time, report the resistance reading on all 3 pads.

Yes, that is what I meant to say.

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Hi, thanks for the replies. I have set my multimeter to 200 ohm which is the lowest on the settings and it gives a default reading of 1 without doing anything, so I put 1 prong on the chassis and the other on 1 of the pads but the reading doesnt change - am I doing something wrong? This happens on all 6 solder pads (3 pads per component). Also I notice with both components removed the charger LED no longer flickeres.

Thanks

[ben7]

Re: Adapter LED flashing, laptop not switching on

Hi, thanks for the replies. I have set my multimeter to 200 ohm which is the lowest on the settings and it gives a default reading of 1 without doing anything, so I put 1 prong on the chassis and the other on 1 of the pads but the reading doesnt change - am I doing something wrong? This happens on all 6 solder pads (3 pads per component). Also I notice with both components removed the charger LED no longer flickeres.

Thanks

I have a feeling that the control chip for the MOSFETS could be fried, causing them to both turn on and the same time, and overheat.

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Hi Ben thanks for your time, would the controller chip for the MOSFETS be the 48-pin surface mount chip next to the DC Jack named ISL9504? I have googled the chip and some1 is calling it the Power IC, would this be the chip you're refering to? If not could you possibly identify it from my picture please? I can replace these chips if need be as I have done 128-pin ic's in the past not much bigger than this 1.

Thanks

[ben7]

Re: Adapter LED flashing, laptop not switching on

Hi Ben thanks for your time, would the controller chip for the MOSFETS be the 48-pin surface mount chip next to the DC Jack named ISL9504? I have googled the chip and some1 is calling it the Power IC, would this be the chip you're refering to? If not could you possibly identify it from my picture please? I can replace these chips if need be as I have done 128-pin ic's in the past not much bigger than this 1.

Thanks

It appears to be some sort of buck voltage regulator controller made by Intersil.
Can't find the datasheet for the ISL9504 though.

Your pic is not big/close enough to be able to read the numbers on the chip.

[aaronmarsh632]

Re: Adapter LED flashing, laptop not switching on

Hi thanks for checking, I have taken a closer image of the chip, i cant find anything that means anything to me through a google search, maby you'll know more about it than me. Heres the pic anyway.

Thanks