My symptoms are a black screen and 10 short blinks and 1 long blink on the power LED.
I'd second the suggestions from BLTCON0, it doesn't sound like a typical memory access problem.
@mechy - yes, the rev6 board uses the 4x256k DRAMs, it's the rev4 board that uses the 1x256k. The many you've supplied me in the past have all been great thanks.
@curtis - before ripping out all the existing DRAMs (and possibly causing more problems in the process), you might like to make a few more diagnostics. For a start check if the system if even getting as far as the memory test. An easy way to tell is use an oscilloscope to see if the memory write enable line (pin 3 on any of the DRAMs) is strobing low. As I recall, you'll see at least two low-going strobes at about 1µSec duration. If it's not doing this, you're certainly not going to get anywhere by replacing the DRAMs.
John H's
DiagROM is particularly useful at this point. If you don't see any serial data out immediately at power on, you've got some other low-level problem going on.
As others have said, if there's been battery corrosion in the past, it's common to get corrosion in/around pin 1 of the 68000 CPU socket which often causes the machine to do nothing at power on, or give you some nondescript error. Cleaning it rarely results in it becoming usable unless the corrosion is very minor. If any of the socket contacts appear green/blue or tarnished/dark grey in colour (should be bright silver) then the entire CPU socket need to be replaced.
