cramer@sun.com (Sam Cramer) (08/18/90)
I've fixed a few Mac Plus power supplies, following the directions in Larry Pina's "Macintosh Repair and Upgrade Secrets" book. I've always had problems soldering a replacement diode to its heat sink; I could never get the solder to stick. Thanks to the folks at Soft Solutions (from whom I bought the upgrade parts), I now know what the problem is. The heat sink is very effective at drawing away heat, and so the solder does not get hot enough to stick to the metal (steel?) surface of the heat sink. The solution is to use a higher wattage gun. I borrowed a temperature-controlled Weller soldering iron from work and cranked it up all the way (to 11). This gave the solder the final push over the edge. I attached a pliers and some alligator clips to the diode lead to avoid burning it up in the process. Sam