Performa 475 Repair

[Macdrone]

200 I'm sure is for drying and getting contaminants off.

400 for 10 min for reflow is what I found what works for me more often than not. It's about 90 percent success rate for me, newer and vintage at this point.

 

[NickNick]

I as well have the exact same issue with a Performa 475 although mine worked perfectly and I was using it, turned it off then on at a different time and this issue started to happen. Recapped it and still same issue. I believe this to be a memory issue though as others have mentioned that a happy chime first followed by a sad chime is a memory issue. Did you ever figure this one out?

 

[Elfen]

Just because it looks like it is a memory issue does not mean that is a memory issue. Rotted out traces to the RAM's Data, Address, Read/Write and Memory Refresh Strobe lines can kill signals going/coming to/from the RAM, thus making it look like a RAM Problem when it is not.

One has to go in with an oscilloscope or multimeter and check every line going to the RAM and fix those lines that registers as dead. Complicating things further, those Data, Control and Address Lines going to the VIAs and other support chips can also add to this problem and they need to be checked out and fixed too. Adding tot he complication even more, rotted solder joints on the chips and the board will add to the problem, so they need to be desoldered, cleaned up and resoldered with fresh solder.

Besides the proof being rotted traces on the board, the other proof to this is that the RAM used in my 475 works well in other machines I use to test it on, so I know the RAM works. The problem is with the board, not the RAM.