abe@j.cc.purdue.edu.UUCP (01/24/87)
The high voltage power supply of my fat Mac went up in smoke about a week ago. The smoke was produced by the failure of a silicon rectifier diode, CR1 (Apple part G1854 8418). After much trial and error I have replaced it with an SK3925, which is an Si-Sw, Fast Recovery Damper diode. It runs very hot. An SK9004, an Si Rectifier (3A 100 PRV) works as well (runs as hot). Some of the inadequate trial replacements were Si Rectifiers with much higher voltage and/or current ratings. Some of them ran so hot they desoldered themselves. I would like to know the proper replacement for CR1. Does anyone know? This is the second failure of CR1 I have observed. A friend's fattened Mac developed bad solder joints on CR1, which produced breakup in the display. He resoldered the joints and has had no problem since. His first suspicion was manufacture error, but I suspect it was a failure caused by overheating. It appears to me that a cooling fan is in order. I would appreciate any recommendations. Please reply via E-mail. I will summarize significant replies. ...!ihnp4!pur-ee!j.cc.purdue.edu!abe abe@j.cc.purdue.edu