Hy theare anibody have the answer about HP54200A scope ,wen turned on only comes up with fatal error ram,chnge the 2 ram chips on the cpu board but it is steell the same error,any help would be much apritiated,Thanks
1 - You may not have replaced the correct RAM
2 - The fault may lie in a memory controller or address logic etc.
3 - The fault may lie in a different subsystem (power supply, etc)
I agree with replacing the RAM first though.
Other than that, I'm not familiar with this scope.