Old laptop power system has failed

[hawkeye_wx]

I've been using an old G50-133us laptop.  In recent months, the power system went bad.  There was a worsening screeching sound when the AC power cord was plugged in.  I've recently discovered that the power from the cord was very intermittent, causing the system to constantly alternate between the external power and battery power.  The screeching noise has been continuing even after the system was powered off.  The system was not able to run with only the external AC power cord connected.  Unfortunately, today I tried running on only battery power.  It worked for 30+ minutes, but when the charge indicator was down to about 80%, the system powered down.  I have not been able to power it up again.  It seems clear some component in the power system has failed.  It's a long shot, but does anyone have any idea what I might try doing/fixing before I consider this old laptop dead?  I just took the system apart to examine the motherboard, but I don't see anything obviously wrong.  I actually just installed a new ssd (two days ago, because the old hard drive was failing) in an attempt to keep the system going for a while longer while I decide what to buy/build for a new computer.  It appears my luck ran out.

[Huffer · Accepted solution]

Yes the problem is almost certainly the motherboard. This is the part number:

For use only with HP G50 and Compaq CQ50 computer models equipped with a GL40 chipset, Digital Media Slot, and HDMI port 485219-001

Service Manual

It might possibly just be the power jack module which plugs into the motherboard:

Power connector cable 486637-001

See pp. 83-84. 

The power jack is very cheap:

https://www.ebay.com/itm/486637-001-50-4H513-001-GENUINE-HP-POWER-DC-IN-CONNECTOR-CQ50-115NR-CA31/27...

The motherboard does not cost much more:

https://www.ebay.com/itm/HP-Pavilion-G50-G60-Motherboard-485219-001-55-4H501/173495473693?hash=item2...

This is a pretty "vintage" laptop but assuming you can do the replacement, an investment of $6-40 might make some sense since you just popped for a new SSD. 

Post back with any other questions and please accept as solution if its the info you needed. 

[hawkeye_wx]

Thanks for the response. 

I forgot to add that the screech/static sound, when the system is off but the power plug is connected, is a repeating, 2-3-second cycle, and it seems to be coming from the general area of the chipset, roughly halfway between the cpu and the battery plug.  It's driving me nuts that I can't specify the exact source.

Also, one other thing I noticed when the system was working was that the noise diminished when the cpu was being stressed, then became noisier again when the cpu was idle.

You are probably right that the way to "fix" this issue is a motherboard replacement.  I appreciate the ebay links.  However, even though the $30 cost isn't bad, I really shouldn't be putting any additional money into this old system.  I bought the ssd because there was a good black Friday sale and I was just hoping to milk the laptop for a while longer.  I knew the noise likely meant it was on its last breath and could die at any time.  Whenever I buy/build another system I can throw the ssd in there.

Still, I'll keep trying to pinpoint the noise and try to pull a miracle out of my hat.

[hawkeye_wx]

I guess the noise is not always that loud screech.  At the moment it's more subtle, briefly stopping once every several seconds.  When it briefly stops, the charging light flickers one time.  Then, it repeats.  Of course, it's likely none of this really matters.  I'm just adding any details I can think of.

[RacerRex]

Hey, here's a thought: have you tried cleaning/lubricating the cooling fan (CPU heat-sink assembly) ? 

Not sure what else could be making that noise except the old hard drive cyls.

Just got an idea... This is stupid mind you. If this is it your gonna kick yourself: check for an old cd/dvd in the optical drive??

Best of luck 😉

[hawkeye_wx]

RacerRex,

Thanks for the suggestion, but this HP laptop is no longer being used.  Back in January, the AC power finally stopped working completely and the battery quickly ran out of juice.  Fortunately, my brother had an old iMac he could pass down to me.  It's the same old age as the laptop(2008), but it's a much better system.  The 35W laptop was quite underpowered, more than I realized.