(Topic ID: 307484)

sys11 b - u25 ram failure

By mr-zed

2 years ago



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  • Latest reply 2 years ago by mr-zed
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    #2 2 years ago

    Power measurement, that depends on where you measured. Should be seeing close to this:
    MPU IJ17 Pins 4,5,6 = +5.03 VDC @8.1 mV AC ripple
    U26/U27 ROM Pin 1 = +4.91 VDC

    If you measured 4.86 at the PSU you are going to probably find even lower at these points. BUT, the common symptom of low power is random resets and lockups. The failure you are seeing, my guess, is corrosion related most likely. If not, it could be another IC that is on the address/data bus that the RAM is having trouble with.

    #6 2 years ago

    Yes, its bad enough. That corrosion is likely to migrate, or creep, into many of those components, and possibly already has. It could cause many problems. There is a few good threads on the subject of correcting it properly on this site, in order to repair and ensure reliable operation in the future. In a nutshell, removing all potentially affected components, carefully neutralizing and removing all traces of corrosion, and reinstalling new components. Not an easy quick fix for this series of board, but possible.

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