"DaveC" wrote in message news.net... Mac PowerBook G4 won't boot (but will give the boot "bong"). If I press on the case below the motherboard, it boots and, if pressure is maintained, functions normally. If pressure is released, video will scramble, and -- sometimes -- system will freeze. I've run the mboard out of the case with just power, and pressed, squeezed,etc. without any hint of what I'm looking for. I've examined it with a glass looking for cracked board and/or traces, separating solder joints, the obvious. It does still fail out of the case, so this isn't a short-to-case issue. Any ideas what else this might be? Do ASICS and other ICs fail (internally) in this mode? It's gotta be a trace, solder joint, or via. Try resoldering anything in the area, if that doesn't work and it's otherwise garbage, you could try heating up that area of the board with a heat gun until it's hot enough to melt solder then let it cool off. |
On Thu, 26 May 2005 14:29:27 -0700, DaveC wrote:
Mac PowerBook G4 won't boot (but will give the boot "bong"). If I press on the case below the motherboard, it boots and, if pressure is maintained, functions normally. If pressure is released, video will scramble, and -- sometimes -- system will freeze. I've run the mboard out of the case with just power, and pressed, squeezed,etc. without any hint of what I'm looking for. I've examined it with a glass looking for cracked board and/or traces, separating solder joints, the obvious. It does still fail out of the case, so this isn't a short-to-case issue. Any ideas what else this might be? Do ASICS and other ICs fail (internally) in this mode? Thanks, It's probably a bad solder connection, but as others have said, it could be a crack in the board. I've seen a number of laptops with bad soldering on the DIMM sockets. Try resoldering everything that's easy to resolder with the equipment you have. On a board like that, there won't be much that's easy to resolder. If the problem is on a BGA IC, you're out of luck. I guess you could try putting the whole board in an oven hot enough to melt all the solder. It sounds crazy, but that's how it was originally soldered at the factory. Andy Cuffe -- Use this address until 12/31/2005 -- Use this address after 12/31/2005 |
"DaveC" wrote in message news.net... Appropriate temperature for this experiment would be 375F? (Google says melting point of 60/40 is 356.) Leave it in for 10 min? 20? -- Please, no "Go Google this" replies. I wouldn't ask a question here if I hadn't done that already. You're probably better off with a heat gun so you can localize it, if you just put it in the oven the parts will fall off the bottom. |
"DaveC" wrote in message news.net... On Sat, 28 May 2005 00:15:59 -0700, James Sweet wrote (in article PUUle.10023$Ri3.5477@trnddc09): You're probably better off with a heat gun so you can localize it, if you just put it in the oven the parts will fall off the bottom. So how do they stay on for the original wave soldering? That is done with the PCB face-down, I believe. -- They're glued on, so you might have some luck, but I've salvaged components by heating them until they fell off, so maybe if you don't go quite as hot the glue won't melt. |
On Fri, 27 May 2005 23:24:44 -0700, DaveC wrote:
On Thu, 26 May 2005 21:05:36 -0700, Andy Cuffe wrote (in article ): I presume that components are physically attached to the PCB with high-temp adhesive before soldering. I'm concerned about components on the underside of the PCB falling off when the solder goes liquid. If that's not an issue, I'm ready to try it. If I destroy the PCB, I'm not any further behind; I need a new motherboard anyway... The components are glued on, but it's possible that some of the glue has cracked with age and parts could fall off. The surface tension of the solder should hold the small parts on, but heavy parts could fall off if the glue has cracked. Put it in the oven with the large parts on top. In the factory, they silk screen a solder and flux paste onto the solder pads, then glue the components on. Finally, it's pulled through an oven using a conveyer belt. It's important for the board to get hot enough to melt all the solder, but not hot enough, or long enough, to damage any of the components. I'm not sure if you could get even enough heat in a kitchen oven. I have no idea what temperature you should use, or for how long. As others have said, a heat gun might be better if you can narrow down where the problem is. What ever you decide to try, I would get a junk board to practice on. A few seconds too long with the heat gun could burn the board. Let us know if it works. I've never tried anything like this. Andy Cuffe -- Use this address until 12/31/2005 -- Use this address after 12/31/2005 |
Dave, as a suggestion perahps you could try the Mac groups etc to see if you can
find someone with a similar unit, but crook or broken screen - might be a cheap way to solve the problem. Another idea would be to talk to a Mac technician - he may know any common troublespots on your model board David - who hates to see a good Mac go down DaveC wrote: If that's not an issue, I'm ready to try it. If I destroy the PCB, I'm not any further behind; I need a new motherboard anyway... -- |
On Sat, 28 May 2005 07:15:59 GMT "James Sweet"
wrote: You're probably better off with a heat gun so you can localize it, if you just put it in the oven the parts will fall off the bottom. I've done things like this a few times, and the technique that I found that seemed to work best was to position the board just above (1-2") a hot plate, and set the hot plate to just below the solder melting point. Then I could go into the board with a heat gun or soldering iron, depending on the task, and apply the small amount of additional local heat that the job required. - ----------------------------------------------- Jim Adney Madison, WI 53711 USA ----------------------------------------------- |
"quietguy" wrote in message ... Dave, as a suggestion perahps you could try the Mac groups etc to see if you can find someone with a similar unit, but crook or broken screen - might be a cheap way to solve the problem. Another idea would be to talk to a Mac technician - he may know any common troublespots on your model board Hah! A Mac technician? I remember those guys back when I was in highschool and the labs were filled with Macs. They'd come in and start swapping boards without doing any sort of troubleshooting at all. I'm sure there's some hardcore guys out there who attempt component level work but I've never encountered one. The idea of finding another one with a busted screen is a good one, ebay is good for that too. |
On Mon, 30 May 2005 13:58:34 -0700 DaveC wrote:
On Sun, 29 May 2005 19:44:19 -0700, Jim Adney wrote (in article ): I've done things like this a few times, and the technique that I found that seemed to work best was to position the board just above (1-2") a hot plate, and set the hot plate to just below the solder melting point. Then I could go into the board with a heat gun or soldering iron, depending on the task, and apply the small amount of additional local heat that the job required. Thanks, Jim. This sounds like a good approach. It brings up a couple of questions: how can I be sure that I don't exceed the pre-heating temperature (with the hot plate)? I don't want components dropping off of the underside of the board. And once I start to heat the topside of the board with the gun, how can I be sure I don't exceed the melting point of the solder? I understand that getting things too hot will melt the solder connections within an IC (they use a higher melting point solder to avoid this problem during manufacture of the PCB, or so I hear.) You may have to work up on the hot plate temp. The trick is to use it to heat the under side of the board to just below the melting point, so that the extra heat from your iron or heat gun will be enough to melt the parts you're interested in. I don't think there is any solder in IC connections. The connections there are spot welded. The temp concern with ICs is that high temps will cause the doping ions to migrate and this migration may ruin the careful construction of the IC. This will be a time*temp thing, so you need to work as fast as you can. ICs and transistors may have the silicon die soldered to a metal base, but I'll bet that this solder will be somewhat higher temp than where you need to work, but that's why you need to be careful not to heat any hotter than necessary. Yes, it sure seems touchy, but I've managed to succeed a couple of times, with no failures so far. - ----------------------------------------------- Jim Adney Madison, WI 53711 USA ----------------------------------------------- |
"DaveC" bravely wrote to "All" (30 May 05 12:33:01)
--- on the heady topic of " Laptop motherboard fixes with pressure" Da From: DaveC Da Xref: aeinews comp.sys.mac.hardware.misc:9529 Da sci.electronics.repair:49238 Da On Sun, 29 May 2005 18:14:33 -0700, quietguy wrote Da (in article Da ): ... Da as a suggestion perahps you could try the Mac groups etc to see if you can find someone with a similar unit, but crook or broken screen - might be a cheap way to solve the problem. Da That's the backup solution. I've got nothing to lose by trying the Da heat solution first. Another idea would be to talk to a Mac technician - he may know any common troublespots on your model board Da Already have, several. They all say "replace the motherboard". Nothing Da against them; they've learned the modular-replacement method. I'm Da looking a little closer than that. Dave, They are not too far off the mark actually because a modern pc motherboard is a rather sophisticated piece of technology. To be fair, I'm assuming you have little repair experience and even less equipment than is available in a well equiped kitchen. Put it this way, it is as if you were to attempt brain surgery with stone knives and suture the wound using bone needles. Please, forgive me if my assumption is wrong. A*s*i*m*o*v .... Back when I was a boy, we carved our own ICs out of wood. |
Why not spend an hour or so with a high power magnifier and look for
obviously poor soldered components before embarking on this potentially distructive approach? DaveC wrote: On Sun, 29 May 2005 19:44:19 -0700, Jim Adney wrote (in article ): I've done things like this a few times, and the technique that I found that seemed to work best was to position the board just above (1-2") a hot plate, and set the hot plate to just below the solder melting point. Then I could go into the board with a heat gun or soldering iron, depending on the task, and apply the small amount of additional local heat that the job required. Thanks, Jim. This sounds like a good approach. It brings up a couple of questions: how can I be sure that I don't exceed the pre-heating temperature (with the hot plate)? I don't want components dropping off of the underside of the board. And once I start to heat the topside of the board with the gun, how can I be sure I don't exceed the melting point of the solder? I understand that getting things too hot will melt the solder connections within an IC (they use a higher melting point solder to avoid this problem during manufacture of the PCB, or so I hear.) Thanks, -- Joe Leikhim K4SAT "The RFI-EMI-GUY" The Lost Deep Thoughts By: Jack Handey Before a mad scientist goes mad, there's probably a time when he's only partially mad. And this is the time when he's going to throw his best parties. |
"DaveC" wrote in message news.net... On Mon, 30 May 2005 21:32:37 -0700, THE-RFI-EMI-GUY** wrote (in article ): Why not spend an hour or so with a high power magnifier and look for obviously poor soldered components before embarking on this potentially distructive approach? Thanks, REG. I did that. Yes, it's best to look for the obvious *one* failure rather than attack the whole board, but I'm down to that choice, now: heat it and hopefully fix it, or pay for a replacement board. Nothin' to lose, right? Might be helpful to poke around on the board with a sharper tool, like a philips screwdriver with electrical tape on the end to insulate it. Then you may be able to localize down to a more specific component. |
Andy Cuffe writes:
If the problem is on a BGA IC, you're out of luck. I guess you could try putting the whole board in an oven hot enough to melt all the solder. It sounds crazy, but that's how it was originally soldered at the factory. But they ususally do this before the plastic parts are attached. Try it at home and you may find slag where you once had DIMM sockets. -- David |
"DaveC" wrote in message news.net... On Wed, 1 Jun 2005 15:11:49 -0700, David C. wrote (in article ): But they ususally do this before the plastic parts are attached. Do you know this for a fact? The SODIMM sockets are surface-mount solder tabs just like all the other components. They look like they are soldered right along with all the other components... Try it at home and you may find slag where you once had DIMM sockets. Maybe. Maybe not. The board's toast, anyway. Nothing to lose. YMMV, just be very careful not to go too high or too long with the temperature. |
On Tue, 31 May 2005 18:14:38 -0700 DaveC wrote:
On Mon, 30 May 2005 20:21:42 -0700, Jim Adney wrote (in article ): ICs and transistors may have the silicon die soldered to a metal base, but I'll bet that this solder will be somewhat higher temp than where you need to work, but that's why you need to be careful not to heat any hotter than necessary. What about plastics? There are several sockets (for RAM SODIMMs) and headers (for connector cables from HD and keyboard, etc.). Also some plastic film that wraps around the edge of the PCB where it mounts to the back of the laptop's case, presumably to insulate the edges of traces from shorting to the case. You'll have to be careful of the plastics. They will soften and may be ruined. The ones I've dealt with must have been added after soldering. - ----------------------------------------------- Jim Adney Madison, WI 53711 USA ----------------------------------------------- |
On Wed, 01 Jun 2005 06:27:03 GMT "James Sweet"
wrote: Might be helpful to poke around on the board with a sharper tool, like a philips screwdriver with electrical tape on the end to insulate it. Then you may be able to localize down to a more specific component. The localized pressure idea is a good one, but I'd stick with a totally nonconductive tool. There are many possibilities: popsicle stick, Bic pen turned around, plastic knitting needle, plastic tuner alignment tool, etc.... - ----------------------------------------------- Jim Adney Madison, WI 53711 USA ----------------------------------------------- |
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