A4000 Replica Fast RAM problem

[kuculin]

Hi Guys

I'm looking for some advices.
So i'm building the A4000 replica. I go along Chucky's manual. Everything is good and working, but when i got to fast RAM, problem occured.
When i put in fast ram sticks and run the Diag ROM, after start it says amount of fast RAM, but any test fails and doesn't see any RAM.
I beeped all Ramsey and SIMM pins and routes and all is ok.
So i poked around with oscilloscope during fast RAM area test running and here is the outcome:

FIrst the obvious bad ones

_WEO and _BUFEN are always high no activity at all.


Signals with activity
RW _B_RW MA0-MA9 FC0 FC1 AS DSACQ R_W _R_W SIZ0 SIZ1 _STERM _RAS 0-3 _CAS 0-3

Other signals always high:
FC2 DISRAM(_WAIT) DMAEN _CBREQ _CBACK


So i'd like some advice if i can do any more tests before i'll deem the Ramsey dead and start looking for a new one.

Thanks for looking and have great time
Kuculin

PS:Ram and cpu card are tested and ok.Voltage on board 4.89v

[alexh]

There are no fast RAM SIMMs fitted to the board in the photo. Are you sure you're looking at the right addresses?

[kuculin]

Photo is just illustrative



Main problem is the signals _WEO and _BUFEN are always high and therefore no buffering and no RAM writing happens

[kuculin]

Even with 16 mb RAM inserted and fast ram tests in diagROM running .... _WEO and _BUFEN always high ...