Dead 512k, rapid clicking?

[bibilit]

So you replaced the whole set of chips ??

 

[tattar8]

That’s right.

 

[bibilit]

No broken trace when removing the old chips ?

 

[tattar8]

There was one on one of the sweep lines but I fixed it.

 

[tattar8]

I verified continuity from one RAM chip to another (for the 14 pins that are all connected in each row), plus continuity from the Data pin of each chip to the 68000 and continuity from the RQ pin to the 74LS166 shift registers, the 74LS244 buffers, and the 74LS161 counters.

However, at some point I did manage to accidentally crack ceramic capacitor C47 in half; this seems to be the point at which the chime stopped playing, so I suspect that that capacitor has something to do with the sound subsystem.  Is this a correct assumption?