HP G62 NB reballing and undervolting

[Th3_uN1Qu3]

As promsed, here it is. This isn't the first laptop this guy brings in for me to fix, and he told me he bought it for his dad, so i tried my best to do a good job.

Apparently it had been reflowed before, but other than the epoxy being removed from the corners of the NB, i saw no other signs. And the bad solder balls were visible to the naked eye on the edges. So i think whoever attempted to reflow it used a hair drier or something... Still, better than using a heat gun and frying the board beyond repair.

Reballing went smooth with no problems, as usual for these RS880M chips. I haven't encountered problems with them yet, it's the boards that can be a pain in the rear sometimes. This one was okay.

Notice the crap brownish paste in the first pic. Don't know what that stuff was, but i cleaned that stuff off put MX-4 on it before putting it back together I also found a shim on the NB, cut to size rather nicely. I called him to ask, and he said it wasn't there, he did it. I thought it looked good so i put MX-4 on both sides and sandwiched it back in there.

I also did some undervolting to the NB core, you can see the mod in pic 7. I could've likely gone further down, but i wanted a 100% stable mod that i won't have to tear the laptop down again to tweak it. The mod i did lowers NB core voltage by about 12%. I don't recall the exact numbers right now, i'll get back with more data once i get home.

I'm posting from it right now, it's been running for a good few hours no problem. As for the temperatures, well, i can't tell you. Not that it's a secret, but it doesn't have a temp sensor! The back gets warm but not hot, and BatteryBar reports ~16W of power consumption when running on battery browsing the web. I think that's fairly good for what it is. It's got a 2.4GHz Turion II and 4GB DDR3 memory, and it's the model with integrated graphics.

I'll upload the Excel spreadsheet for calculating the voltage output of the RT8208A regulator used for the NB core in a bit. Keep your eyes peeled.

[dellxps15]

Re: HP G62 NB reballing and undervolting

good work!!! i did a g62 but was an intel version didnt think of undervolting nb because im afraid of bad stability and wont notebook come back after few days.... even if it can happen when reballing

did u go with 0.35mm balls ? or normal 0.5 ?

[Th3_uN1Qu3]

Re: HP G62 NB reballing and undervolting

Intel chipsets generally come with the right voltage from the factory. You could have undervolted GPU though.

With those AMD RS880M so far i think the chips themselves are good. The boards have too small pads and i think that's why they break.

Why would i go for smaller balls? It was made for 0.5mm balls, i used 0.5mm balls. 63/37 of course.

Spreadsheet is attached. Putting a 4k7 in parallel with the existing 2k67 in PR72 position resulted in a 1k7 equivalent resistance (they left room for it so why bother removing the original one?). This translates to a decrease from 1.1v on the high step to 0.97v, and from 0.95v on the low step to 0.88v. This may not sound like much, but a quick calculation reveals it decreased the power consumption of the NB by roughly 2W, which is still significant. A cooler machine with longer battery runtime is always welcome.

[Uranium-235]

Re: HP G62 NB reballing and undervolting

you got it so hot the solder came up on the blank places. You should try to ball some GDDR chips in those places

[Th3_uN1Qu3]

Re: HP G62 NB reballing and undervolting

Nah, the solder was there from the factory. I got it as hot as it needed to be, no more, no less.

This is the onboard graphics model, but there IS a place next to the NB for a chip of DDR2 or DDR3 (can't be arsed to look up the datasheet now), acting as "sideport memory" for the IGP. I could have fitted that in, but it wasn't my laptop. I've already given it back yesterday.

Little bit of a bonus tho, i might be hooking up with this guy's sister. He was out of town so he gave the laptop to her, and it's her again who picked it up. When i received it i was late and she was tired from work, so i didn't want to try anything as she was probably mad at me for being late, but i thought she was kinda cute and left a mental note to try and get a date when we meet to give her the laptop back.

This time i arrived on time and thought "what the hell" and went out of my way to hang around with her a bit. Then i asked if i can keep her number and call her so we can go out again sometime, and she said yes.

I love my job.