Anyone want to sacrifice a 6500 mobo for an experiment?

[Quadraman]

I was looking at this

http://en.wikipedia.org/wiki/PowerPC_G3

and found this

"The PowerPC 740 is completely pin compatible with the older 603, allowing upgrades to the PowerBook 1400, 2400, and even a prototype PowerBook 500/G3."

So it got me to thinking that MAYBE you could desolder the 603 from a 6500 motherboard and solder a G3 in it's place and MAYBE get a recent version of OS X running on it. I don't have the solder skills or the parts to spare for something so delicate, but maybe someone here does? Does anyone think it's possible?

 

[Bunsen]

First of all, follow the links through to the source documents and find out if this is in fact true.

Second, find a 740

 

[Franklinstein]

I've looked into it and read several IBM documents regarding BGA devices.

Essentially, it IS possible to do with a heat gun and a NEW PPC 740, but don't try to do it with a pulled 740 unless you've had it re-balled with all new solder balls.

Ideally, one would have a new chip and a specialized workstation that uses very hot gas, the temperature of which is precisely controlled. A precision tool would be used to remove the old BGA device and clean the pads on the board, including removing any balls that remained stuck to the board. Then, the new chip would be mounted precisely and melted into place.

Reworked BGA devices use the same setup, but the device to be reworked is pulled and the balls are removed. Then, the chip is placed in what looks like a garlic press, and new balls are installed thru the holes in the bottom and adhere to the chip. Then, the chip with its new solder balls is replaced onto the board and melted down again.

Some of the IBM documents showed that on each subsequent removal of a BGA device from a board, it gets messier every time. Typically, more and more balls stick to the board as opposed to remaining on the BGA device, and the pads can become worn and reluctant to hold solder.

It's a neat idea, and I still wanted to try, only more with replacing the 250 or 292MHz 750s on Wallstreet daughter cards with 750L chips in the 400-500MHz range. I really don't think any upgrades from Newer or anybody utilized the 83MHz system bus. I also thought about replacing the BGA 603e in a PowerBook 3400 with a faster one, but it's hard to find a 603e over 300MHz, so it's a bit pointless.

Anyway, the OS X issues on the Gazelle models (and Tanzania machines like the 4400 or Starmaxes) are related more to the other system hardware rather than the 603. I mean, a 3400 and a 2400 can run OS X to 10.2 without much issue (though slowly), and they're both 603e machines.

 

[Unknown_K]

Sounds like expensive equipment will be needed, know of any place you could find it?

 

[Bunsen]

Expensive is an understatement.

Even if you get a faster clock-rated CPU in there, it'll still be running at the same speed as the old CPU, won't it?

And are the 603s in the desktops also BGA? I wasn't aware of that.

 

[Franklinstein]

@ Unknown_K: I have no idea where to get stuff like that locally. There are some shops that'll do the work for you, as there are for repairing the BGA GPU on defective iBook logic boards. I'm not willing to pay for it, though.

@ Bunsen: It depends on the model. The 54/6400 had 120, 140, 160, 180 and 200MHz QFP chips, while the 7220/4400 had 160 and 200MHz BGA chips, and 55/6500s had 225, 250, 275, and 300MHz chips. Clones were variable, as well, but most Tanzania boards were BGA.

It's not hard to change the clock frequency of many of the later models, particularly the Tanzania clone boards (which are designed for multiple 603/604 configurations) and Gazelle models: it's just a couple of resistors to change the clock speed. Much easier than trying to figure out the clock config on a PB 5300...

 

[trag]

@ Unknown_K: I have no idea where to get stuff like that locally. There are some shops that'll do the work for you, as there are for repairing the BGA GPU on defective iBook logic boards. I'm not willing to pay for it, though.

Reballng kits with a proper stencil for the part you're reballing can easily cost in the $400 - $700 range. For example, this kit:

http://practicalcomponents.com/tools_supplies_training/bga-reballing-kit.htm

costs $650. Of course it comes with enough solder balls to reball hundreds of chips. It's not worth it if you're only going to do one or two, unless you're doing it for a wealthy client. However, there are less expensive options available on Ebay without customized stencils (you tape off the unused holes). But those Ebay options are still about $300 once equipped.

After you have the balls properly positioned, you still must heat the part with hot air or bake it to attach the ball to the part. Otherwise when you turn it over the balls are likely to fall off.

BGA soldering is probably more easily done with a customized toaster oven, than with hot air, but either way will work and both methods have ads and dsads which vary depending on your experience level.

The tricks to BGA soldering are component preparation, using good flux on the board (esential), proper (registration/alignment) placement of the part on the board and most importantly, a usable thermal profile. The thermal profile is how long the part and board spends at each temperature.

For one or two parts it probably is cheaper to pay a professional shop, and it will cost at least $75 and possibly $300.

It's not hard to change the clock frequency of many of the later models, particularly the Tanzania clone boards (which are designed for multiple 603/604 configurations) and Gazelle models: it's just a couple of resistors to change the clock speed. Much easier than trying to figure out the clock config on a PB 5300...

You must also double check whether newer fast CPUs use the same voltage levels as the chip you are replacing.

When I experimented with replacing the PPC601 on 6100 and 7100 boards I found that the original PPC601/66 or PPC601/80 ran on 5V, but the later PPC601/100 that I was trying to use expected 3.3V.

Jeff

P.S. A hardware store heat gun can be used as a source of hot air. However, it is desirable to control the heat level and the air speed. Home Depot used to sell a Milwaukee brand model with a continuously adjustable temperature dial on the back, I don't know if they still do. That would just leave applying a control to the blower, or living with the air speed which it uses.

Also, nearby parts can be masked with modeling clay, so you do not blow them off the board.

 

[MacJunky]

If you had the time could one not just use specially cut metal blocks in place of solder balls? I suppose you might want a grid of ceramic rods or something to hold the blocks in place while soldering with a heat gun but one would think that could work if you had a conductive paste that you could apply&heat to work with.. In theory I suppose.

This gets me wondering, People use rear window defroster paint in place of solder&resistors when overclocking their G4s and portable G3s, What is the resistance like with this stuff? Might it be usable? I have never actually played with it in this manner so I have no idea.

 

[Quadraman]

First of all, follow the links through to the source documents and find out if this is in fact true.
Second, find a 740

The 740 was used in a lot of laser printers. If you have a junk one laying around, you could try to remove the 740 from it for the experiment.

 

[Bunsen]

I have to agree with trag about the preference for getting a pro reflow shop to do the transplant. You will find links to decent shops in the US in the interminably long iBook G3 motherboard issues thread on Applefritter.

However, if you still want to have a DIY crack at it, here are a couple of suggestions.

You can make a solder mask by chemical etching a very thin sheet of copper, as you would etch a PCB. ie, make up a pattern for the BGA balls in your favourite CAD program, then proceed as per transferring PCB artwork to a PCB, except using the thin copper sheet instead of a PCB. With luck, you'll etch neat holes all the way through the sheet.

Secondly, check out Sparkfun's $90 toaster oven reflow controller kit.

Thirdly, even if you can't upclock the CPU, a G3 is supposed to outperform a 603 at the same clock speed.

 

[Quadraman]

I have to agree with trag about the preference for getting a pro reflow shop to do the transplant. You will find links to decent shops in the US in the interminably long iBook G3 motherboard issues thread on Applefritter.
However, if you still want to have a DIY crack at it, here are a couple of suggestions.

You can make a solder mask by chemical etching a very thin sheet of copper, as you would etch a PCB. ie, make up a pattern for the BGA balls in your favourite CAD program, then proceed as per transferring PCB artwork to a PCB, except using the thin copper sheet instead of a PCB. With luck, you'll etch neat holes all the way through the sheet.

Secondly, check out Sparkfun's $90 toaster oven reflow controller kit.

Thirdly, even if you can't upclock the CPU, a G3 is supposed to outperform a 603 at the same clock speed.

Do you have a link to the AF thread? I can't find it.

 

[register]

This gets me wondering, People use rear window defroster paint in place of solder&resistors when overclocking their G4s and portable G3s, What is the resistance like with this stuff? Might it be usable? I have never actually played with it in this manner so I have no idea.

My experience with most conductive paint is a lack of mechanical strenght. But there are some products available for industrial use, to ease the shift from usual soldering processes to RoHS compliant production. The best electrical conductive glue I have tested so far is 2-component silver filled epoxy resin from manufacturer Panacol. It is pretty expensive but allows for repair work otherwise impossible (as for parts that must not be soldered or welded but need a reliable conductive bond). The product Elecolit 325 can be used like a common 2K-Resin curing at room temperature with enough time of 2 hours to apply the sticky mixture. The electrical properties as well as mechanical strength are impressive. See the data sheet on:

http://www.panacol.com/images/pdf/el325_gb.pdf

The company supplies samples upon request, but they will charge around USD 50 for handling and shipping a sample of 10 Grams.

So if you managed to make and align a mask to apply the conductive glue in a porous printing process, to have equal portions of glue in place of each solder ball, you could try to mount a cleaned BGA device with conductive glue. You would need to prepare a spacer also, to hold the BGA device in proper separation of the pcb, or else the glue portions might combine to a film, causing shorts. And practice with some samples before attempting to work on a living board, best on a piece of glass for visual examination of the result. This method allows only for one shot.The epoxy resin gets damned hard, when cured. It is more than likely to destroy the processor or the pcb when you try to get them apart, again. Check for electrical function after the recommended curing time, or else you might mess up the connection. Also check operation with mounted heatsink, only.