Nestamicky and others in this group want to know how I've successfully reflowed the ball grid array (BGA) solder to solve video chipset problems in G3 and G4 iBooks and some G4 PowerBooks. I've also used the same technique to reflow the solder and fix the G4 iBook U28 chip problem, and a loose G5 iMac video chip. First, despite the fact there are a couple of companies that advertise reflows on eBay, successfully reflowing BGA solder is an art, not a science. Not even a megabuck reflow station with flux flushing and X-ray capabilities can successfully revive a computer or X-Box or other device with a BGA-installed video chipset that has one or more broken joints. I know, I've paid hard cash to learn that a professional reflow cannot perform a miracle, though it succeeds in enough instances to make it appear that way.
That's where art comes in. And the art derives from experience and learning everything you can about a particular logic board in a particular machine. If you pay close attention to an iBook, say, and patiently examine it, test it, stress it, and run a myriad of trial and error procedures, sooner or later you'll arrive at an "aha" moment where you understand whether it can be repaired successfully using the reflow method, or not. That's about all I can say. If an iBook makes a chime sound at startup, that is a sign of a successful power-on self-test (POST) that indicates the basic machine is OK. (But I've successfully revived iBooks that refused to chime, too, just as I've failed to revive iBooks that did chime.) The next thing to do is run the model-specific Apple Hardware Test. That will tell if the logic board has a video or other problem, assuming the board will support complete booting and then operation. If the board chimes and then crashes, it could be anything. But bad video will shut down a laptop every time, even if it chimes and begins the boot sequence. Beyond all this, the only way to figure out what's wrong is to play around with a completely assembled iBook and gather clues. One technique I use is to remove the iBook's bottom case and inner shield so I can position a screwdriver handle directly under the video chipset. Then I attempt to start the iBook and boot into Open Firmware, which has much less demanding video requirements than an OS boot. If the OF screen doesn't come up when I hold down Command, Option, O and F, I try it again, putting gentle downward pressure on the left palm rest above the video chipset. (I'm careful to not exert too much pressure because the fragile hard drive is directly between the palm rest and the video chipset.) Usually, this gets the OF screen to appear. Then I clear any corruption caused by previous aborted boots or bad-video shutdowns during starts by typing these three lines, hitting the enter/return key after each line is typed: set-defaults reset-nvram reset-all Quite often, the iBook will chime, start, boot and run perfectly when I finish this sequence and hit enter/return the last time. Sometimes I have to keep pressure on the chipset with one hand while I'm typing with the other. Sometimes I have to play around with this process until the right amount of pressure elicits the OF screen and subsequent successful boots. Sometimes I have to use lots of pressure, just short of making the hard drive do zing-zing noises. Once I get an iBook running and it reaches a stable temperature, I usually can remove the pressure as the heat has closed the broken solder gap(s). I then let it run for hours while I run the Apple Hardware Test and/or the appropriate Apple Service Diagnostic disk (G4 and G5 models), and watch for screen artifacts and syptoms. If arcing caused by broken joints has caused internal video chipset damage, it will show as an error during the AHT and the test will stop at that error. That error usually is not fixable with a reflow. So I stop right there and don't waste any more time on that logic board, except to try one reflow in case the error was caused by a broken solder joint and not irreparable damage to a video trace. (Some people have had the chipset replaced with a known-good one, but that's way beyond my capabilities and financial resources.) I also manipulate the iBook during testing and while it's running the AHT. Sometimes all it takes is a slight lifting on one corner to cause video artifacts to appear or invoke a shutdown. But what happens is part of the clue-gathering process, which can go on for hours until I'm satisfied the iBook has told me all it can. The process is time-consuming, frustrating and physically taxing (scrunched over for hours on end, dealing with tiny stuff), and I only do as much of it as needed. What's worse, all too often no amount of time spent can bring success as there often are multiple problems that I have neither the tools nor parts to resolve. That said, anyone who's interested in the G4 iBook U28 chip issue can learn about one person's "fix" here: <http://www.coreyarnold.org/ibook/> Some people have fixed the U28 by touching each "leg" with a fine solder gun tip while using a magnifying glass. I've found that the process I describe below works just as well, as long as you clean away burned flux and examine the legs carefully for solder shorts after a heat gun reflow with a loupe or magnifying glass. Here's where I learned the basics about how to do successful solder reflows; some of the critical elements were found at links contained within posts at this site: < http://forums.macnn.com/69/mac-notebooks/210232/diy-ibook-dual-usb-logic-board/ > My tools are simple: $20 heat gun; candy thermometer that reads up to 600 degrees F.; aluminum foil with a chipset cutout for heat shielding; a clock; 4 small rocks; solder with a melting point of 430 degrees F. (put pieces on chip being heated to determine when reflow begins; bend pieces to prevent rolling; keep solder away from U28 legs if that's what you're doing); and lots of patience. My last tool is resignation: I only do this if I have nothing to lose. My process: With the iBook upside down and the screen hanging off the edge of my workbench, I place 4 sheets of aluminum foil over the bottom of the iBook. I use an Xacto knife to make a cutout for the video chipset (or U28), being careful to not damage the board. I then use small rocks to weight down the foil so hot air isn't blown under the edges. Next, I take a small piece of solder and bend it sharply so it doesn't roll during reflow. Then I put the solder in the center of the chip and position the tip of the candy thermometer in the bottom of the u-shaped solder opening to help keep the solder from moving. I position my watch/clock so I can see it clearly. Then I take my heat gun, turn it on low and lower it to a few inches above the chip, constantly moving it in a figure-8 pattern to equalize temperatures on the chip. 1) 1-minute warm up to 300 degrees F. 2) 1 to 2-minute increase in temperature to solder melt at 430 degrees F. 3) 45 seconds to 1 minute dwell time at 400-450 degrees F. 4) Slow cool down to minimum temperature on candy thermometer. I am very careful to not jar the laptop during this process in order to avoid moving molten solder in the BGA. I also use a dual-heat heat gun with the switch set on low (750 degrees F.) during warm-up, then moved to high (1000 degrees F.) to get to solder melt and during dwell time. I switch to low and raise the heat gun slowly during cool down. Usually, I'm successful with the first reflow attempt. If not, I increase the dwell time about 15-30 seconds during the second attempt. If that doesn't do it, all bets are off because there likely will be damage caused by the reflow process during subsequent attempts. Also, if a video chipset has been reflowed previously, that logic board makes a poor candidate for a successful reflow. (Been there, done that.) Finally, as I said at the beginning, successful reflowing of solder is an acquired art. My success rate was slightly less than 50 percent in the beginning, but now has climbed to the low 70s over time. I've not had any failures for a year, but only because I have learned to pick my reflow candidates carefully and I've discovered what works best considering the tools I'm using. Good luck if you try reflowing, and don't blame me if you fail, as you most certainly will, sooner or later. Just be sure that you're prepared to write off any failure before you begin. On the other hand, the logic board already has let you down, so you've got nothing to lose. -- Jim Scott --~--~---------~--~----~------------~-------~--~----~ You received this message because you are a member of G-Group, a group for those using G3, G4, and G5 desktop Macs - with a particular focus on Power Macs. The list FAQ is at http://lowendmac.com/lists/g-list.shtml and our netiquette guide is at http://www.lowendmac.com/lists/netiquette.shtml To post to this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/g3-5-list -~----------~----~----~----~------~----~------~--~---
