Date: Wed, 17 Sep 2003 07:23:07 +0100 Subject: Re: SE/30 Locks up at Finder start From: Stuart Bell <[EMAIL PROTECTED]>
On Wednesday, September 17, 2003, at 05:35 AM, Nolen Scaife wrote:
Sorry for the string of posts ;)
After quite a bit of system folder copying and trial and error, I got MacTest Pro to run. "SCSI Controller Failed!" is what it says.
Makes sense!
Well, what are my options? I know I could just replace the logic board, but are there any other methods?
I fear not. Changing the controller chip would be very difficult if not impossible unless you have surface-mount soldering equipment, and the only likely source of a chip would be a donor l/b in the first place.
I think Zilog still sells the 53C80 chip. Digi-Key used to stock it but no longer appears to. A google search turns up Mentor Electronics, but their pricing is not on line, and guessing by their web appearance, I bet they have a substantial minimum order, but I could be mistaken.
All moot, I suppose, because most folks aren't going to do that kind of soldering at home. However, it is doable with soldering pencils (I use a 15 watt and a 40 watt from RS) if you also have some Chip Quik and a good bit of practice.
Chip Quik is an alloy that one melts into the existing solder and it lowers the melting point of the solder. By forming a bead of Chip Quik around the four sides of a PLCC chip like the 53C80, it is possible to heat all the pins on one side of the chip by applying a soldering pencil to any point on the bead.
Alternately heating all four sides on a small chip like the 53C80 will eventually get it to come off the board without damaging the chip or the board, because the melting temperature of the solder has been lowered by the Chip Quik. For larger chips an adjustable heat gun works well to heat all the pins on the chip simultaneously.
One last bit of useless trivia. While a donor logic board would be needed, it needn't be an SE/30 board. Most of the machines (all?) in the Mac II family used the 53C80 as the SCSI controller. The chip can be scavenged from a IIcx for example. The trick is getting someone to supply you with one of these old boards rather than just sending it to the crusher. The low value on these old machines means that the cost in time to handle them is usually greater than the selling price so a huge amount of them are going to disposal. Sigh.
Jeff Walther
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