128K Mac Logic Board Repairs

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Joined: Dec 17 2011 - 12:16
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128K Mac Logic Board Repairs

I have had some success replacing bad RAM chips in 128K logic boards after identifying the bad chips using information in "Dead Mac Scrolls" . I have several more defective boards and need help in identifying the bad components. One displays a Sad Mac Code '040015'. I cannot find this code in any of the material I have. Does anyone know what component(s) this code indicates is bad?
Also, I have another board that has a problem in that the clock will not keep time when the computer is powered off. This usually means a bad battery or a problem on the analog board but in this case the problem is on the logic board. Does anyone know which components on the logic board would be suspect?

In general, I need detailed information on the 128/512K logic board so that I can troubleshoot and repair bad boards.

I am new to this forum and any help or suggestions will be appreciated.