HP envy1" motherboard faulty, trying to repair it, need help

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HP envy1" motherboard faulty, trying to repair it, need help

Postby antoine » Tue Dec 16, 2014 1:34 pm

Hi guys,

My Envy 13 doesn't start anymore, nothing happens when I plug it, no led on, nothing.
I've tested the charger it's okay, I've also tested the 6 points represented below on the pic, they are ok so the alim jack is ok.

Image

Is there anything I can test more to try to find the faulty component?
I found the envy 13 schematics on the web, but it seems like a spagghetti plate to me (the pic below only represents an small part of the 45 pages document):

http://i.gyazo.com/a96ca96047b1ddcc2b75eeba857b027e.png


Is it better to buy a new motherboard instead of losing time trying to repair mine?

Thank you much for your help
Cheers
antoine
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Re: HP envy1" motherboard faulty, trying to repair it, need

Postby Karlsweldt » Tue Dec 16, 2014 5:19 pm

Almost all laptop units have three batteries. The main power battery everyone knows about. But there is a single-cell battery for the BIOS and CMOS features, plus real-time clock. Then the third battery is typically a 5 volt unit, for retention of memory when in hibernation or sleep mode. Those 'other' batteries typically are coin cells, in a shrink-wrap cover. Should have a short leads, with a small polarized plug.
If the BIOS/CMOS battery is dead, then the real-time clock won't function.. and then other bus clocks and circuits may not.
Typical life for that battery is 3 or so years, depending on use. It is a backup for when the unit is not fully active.
The sleep or hibernation battery may be a rechargeable type. Check the owner's manual about replacement for the BIOS battery.
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Re: HP envy1" motherboard faulty, trying to repair it, need

Postby antoine » Tue Dec 16, 2014 5:44 pm

Thanks for the tip, so I've just tested it and it shows 2.95V it seems pretty good...
And I don't think this battery is in cause because when the failure arrived my laptop freezed and I had to manually shut it down and them it never started again. So something has been damaged

I was also searching for some fuse, how many are there usually? I think I've got only 3 fuses and they seem ok.

Also I've randomly tested some condensers near the ACDC Jack (I suppose they are, since they are named PC45, PC625 , etc C means condenser right? there are hundreds of those on the board) and I was surprised to find some are okay (small resistance in ohms) and some seems dead since they show a infinite resistance. is it normal to have dead condensers like these?
antoine
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Re: HP envy1" motherboard faulty, trying to repair it, need

Postby evasive » Wed Dec 17, 2014 10:50 am

some C are in parallel with other components so you are measuring those, not the C. C should be infinite resistance for direct (DC) current.

It depends on the price of a replacement board and how valuable your own time is.
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Re: HP envy1" motherboard faulty, trying to repair it, need

Postby antoine » Wed Dec 17, 2014 11:00 am

yes, I've just ordered another MB from aliexpress, they are very cheap no need to worry about repairing this one.
Thanks guys
antoine
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Re: HP envy1" motherboard faulty, trying to repair it, need

Postby Karlsweldt » Wed Dec 17, 2014 5:22 pm

2.95 volts is too low for a modern BIOS/CMOS battery. If identical or similar to a CR2032 cell, should be at 3 volts. They can only be checked with a digital meter, as the analog type will load the battery excessively. You could use a 3 volt LED lamp, if it glows brightly, the cell is good. The long LED lead is the positive.
A lot of capacitors on a laptop board are Tantalum type, very stubby and may have domed aluminum tops, which is normal.
Not easy to test capacitors in-circuit. A special test unit is needed.
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