Unbootable G5

[CelGen]

I have a dual 2.5 liquid cooled G5 (o-rings were replaced so there is no leaking) that will power on and chime and do all the pre-boot jazz with absolutely no problems (I can even get into the Open Firmware) but the moment you try to boot it the system hangs.

I gave it the original install CD's. It gets to the apple logo (but does not show the spinning animation below it) and then hangs.
I gave it my 10.4 install DVD. Same as above.
I tried my Ubuntu 5.10 PPC discs. That booted a little but just after the kernel is unpacked the system hangs.
I booted into the hardware test disc no problem and it went as far as the memory tests before hanging. I think I know what is wrong
I replace the memory with two matched 512mb sticks (PC3200 400mhz CL3) that I know are working and Mac compatible and run the test again. Same result.
So I guess the ram was NOT the problem.
I reset the PMU. No change.
I checked the battery. Still reads 3.6v
I replaced the optical drive with a known good one. No difference.
Unplugged both 250gb SATA drives (neither have an OS on them). Nothing.
Removed all additional cards but the video card. Nada.
I have run out of ideas on what might be the problem.

[CelGen]

Should of known.... G5 #2 has died on me.
During fuether troubleshooting the red lamp lit up on the primary CPU and the system stopped chiming.
Considering it's less than likely the CPU module itself has died, I'll put $100 on the god damn bridge chip detaching from the logic board. I guess that would explain the previous problem as well.

[beachycove]

Did you clean up the processor cards yourself? If there was any leak at all before the O rings wre changed, there is likely to be crud on the CPU that minimally needs cleaned off.

[ClassicHasClass]

Do any of the front service lights come on? (EDIT: Oh, the red light. Yeah, you're hosed. Logic board.)

[CelGen]

This is pissing me off. That was my second G5 and now I ahve to find another one that's working.
Is there nothing I can kludge? Cardboard shim?

[techknight]

I fixed my imac G5 that was irratic using my IR reflow station.

If you want, you could send the board to me and I'll reflow that chip, but I dont have a tower to test it in. just my imac g5.

So you could ship the whole machine and pay out the a$$ in S&H, or just send me the board, but youll have to test it.

[CelGen]

How big is your IR reflow station?
I have access to one here but the G5 logic board is so large that evenly heating it was impossible and the board warped and killed itself.

[techknight]

You have to clamp the area your going to reflow. cant just "sit it down" that never works.

its the ACHI station that I have. Also you have to know how to use the machine properly, sounds like the wrong profile was ran.

[CelGen]

ACHI covers several models of stations.

[techknight]

I dont remember the model. Actually, I dont care. lol. I just know how to use it, and use it well. I know we bought it in august, and its what they had out at the time.

I had to run a dedicated 220 line to it.

[mcdermd]

Hmm...Are you willing to do IR reflows in general?

I have a 2007 MacBook Pro that may benefit. It seems like one or more of the BGAs are lifting from the board slightly. When it gets cold, I think the solder is thin enough to crack. If I do the XBox 360 fix (cook it upside down in a towel then let it cool) it works well for a good while.

Then there's my late 2006 20" iMac C2D that is in a similar situation as CelGen's unbootable G5. It might work for a few minutes, then freezes and won't reboot to anything but fans. I think it's the Radeon X1600.

Thoughts? Do IR reflows on the BGAs help these types of situations or are they hopeless without a complete reball?

[techknight]

Hey man, No offense, but in my experience is this:

OMG. cook with a towel. ugh....

I have seen SOO many xbox360s that have had this done, plus various other quick fixes, come to me not to be repaired ever again.

Why? there are plastic supports under the GPU and CPU clamping mechanism, and they WILL melt and eventually will squeeze out and short the metal clamp against the board and its supply rails, blowing out the entire DC-DC switching supply.

I was able to fix one of these by rebuilding the DC-DC circuit, and then heatgunning off the melted/fused clamp assembly, with the loss of a few SMD 0402 caps. (hard to rework). But i managed to fix it. the 360 is a 16 layer board as well, and ive seen them short between layers from excess stress, and once that happens its game over unless you have a donor board to transplant the chips as I have done this before as well and its a royal pain in the ass.

Just my 2 cents on the "towel trick" or any other dumb tricks.

As far as doing IR reflows, Yes i can do it, and I am in the states, and it is my day job mostly. I know what im doing As far as reballing, I dont reball unless its absolutely necessary, because reballing as actually worse than reflowing as the leaded solder balls break down more with tension than lead-free, plus reballing requires you to have a 100000% flat board. cannot budge, move, or warp within a micron. Reflow you have a little more give, little less error.

Lead free breaks down more with heat, but leaded is softer so it breaks down under tension. I just use the right flux and reflow them. make sure the balls get all nice and shiny, its good to go for a long time. What allows them to crack is there isnt enough surface tension to stop the solder from being able to rise and crack. Leaded balls, its a bad idea to have tension against it, because it will flatten and bridge. This is why PC CPUs have so much god-awful tension and extreme board warp from the heatsink. There is a reason for that..... xbox360s lack this, and thats why they fail

as far as any other reasons the solder fails, theres a vast majority and its a crapshoot to know the EXACT cause of the solder failure, but my findings if there is enough tension, it does not fail. But the solder that i have seen that does fail, only seems to be on chips that have very large thermal contrast during operation. Such as the G5 system processor running close to 90c then falling down to room temp, and fluctuates during sleep, and in the imac G5s, its a spring tension heatsink, which allows the system processor to be able to expand and has give, which results in what? cracked solder, and air pockets in the solder leading to failure. iBook G3s failed the BGA test as well, well what have we all noticed? yea it gets RED hot under the GPU. plus its not clamped, it has GIVE. and guess what, CRACK, fail....

[mcdermd]

Okay, no more towels! I can't quite figure the MBP. It's fine unless I leave it in an unheated room. Then it doesn't want to post anymore. If I leave it "on" upside down (so the CPU/GPU are right side up) for a little while, it will magically start up and everything is good.

The iMac just KPs after a few minutes of running. I'm fairly certain it's either the Radeon GPU or the VRAM.

Do you guys do reflowing for end users like us? Are you any cheaper than the $200+ that places on eBay charge?

[techknight]

Yup, and hell yea, much cheaper. Sometimes I think I am too cheap, because every once in awhile i just get flooded in game system repairs. But whats even more funny, is I get laptops, mainly the DV7 and DV9 series to get reflown from other PC shops around here too.

The occasional problem I run into though is that stupid epoxy they love to put around the chip. that makes my job just terrible sometimes, because removing that epoxy especially without killing the traces is difficult as best. PC laptops love to use that red shit. Most of the time i just break it loose from the red "crap" enough so i can shoot flux under there to reflow it.

[switch998]

Oh.. My.. God. i thought I was the only one who had issues with that epoxy crap! The BGAs on the iphones are underfilled and the ICs require EXTREME heat to be removed... what a pain in the ass.

Also, with the DV7s, the 1000 series in particular, the FETs on the power in lines go bad more frequently than the graphics do. DV7 2000 and up usually are GFX cards, but a few of the DV7-3000s I got in have had bad power management chips. In short... if you buy HP, you're in for a world of hurt.

One more thing to watch out for on these G5s is the RAM slots, which have really really bad solder joints. I had to repair a few dual 1.8s for that issue so far.

[techknight]

Doesnt matter what you buy anymore. its all of the same design, and the same 2 or 3 manufacturers make ALL of it.

Speaking of which, I have one of those newer all-in-one touchscreen HP systems that is junk, because the ENE System power management controller IC has gone south. It responds to nothing, no input, no LEDs, no power, dead... But it has standby 5V and the keymatrix is toggling the control lines properly when pressed.

[Outlander]

This thread might be a little old, but I just wanted to add that all G5's, and any Macintosh's made from about 2004-2006 are going to be defective. The primary reason is the capacitors on the motherboard. When I worked for apple in those years, they (apple), HP, and Dell decided to use the cheapest capacitors they could buy, and it turned out that the ones they used were purchased from a company that stole the capacitor "recipe" from a major name brand manufacturer, except that they only had part of the recipe to make the capacitors. Anyways, the incomplete electrolyte dries out inside the capacitors in about 6 months to a year, and the capacitors literally pop or explode and leak all over the place. I've repaired many G5's in my day, replace ALL the capacitors, and they magically come back to life.

The second thing is what everyone else has already posted. BGA style electronics SUCK! They can't tolerate flexing like thru hole or SMD style designs, and the solder "balls" literally pop off the motherboard. However.... BGA was used in the past with great success until the arrival of the dreaded "ROHS" compliant solder. Basically a bunch of hippies decided that the small amount of lead was dangerous and had to be removed from solder, well... Lead is what gives solder its flexibility and allows it to stick to the pads and traces. Without leaded solder, BGA electronics literally "pop" off of the board with a little bit of flexing. The fix is to purchase the re-flow kits with the screens for the right BGA chips and use LEADED solder balls, otherwise the repair will just fail again when the motherboard flexes, expands, and contracts. You can just re-flow the boards by sticking them in an oven, like mentioned, or by using a heat gun, but, as I just mentioned, the repair will eventually fail again.

Hope that helps somebody

[CelGen]

We already knew about the caps stuff for a while. I have seen the stream of imacs with vented caps for years now.

I can however agree with you on the ROHS crap. Nobody ever liked it and the transition was a disaster for everyone.

[uniserver]

bought a whole pallet of g5's last year, 1.6, 1.8, 1.8dp, etc, there was quite a few machine that all they needed was to pull the video card out, and pop it back in and it would boot just fine! there were some that were so dusty inside, it was causing dust shorts across the ram, witch an air compressor fixes. out of all the ones on the pallets ( i even had 4 that were so badly smashed that i had to use a sledge to beat the case back to some what of a normal shape and use jb weld and a clamp to get the case back to a semi un-mangled , useable condition,,,, and only had one that had a bad psu and cooked some parts on the main board, but like i said only had 1 that was totally un-fixable, that one i gutted and, turned into a really cool intel mac clone!

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