Follow-up: Apple IIe dead?... Repaired!

[Sabino Maggi <maggi@ien.it>]

Hi to all,
I announce that, after one full month, my A2 Europlus works perfectly
again!

One month ago (I was mostly on vacation in the meantime) I wrote:

> ... a couple of hours ago the machine went dead.
> Now, when I turn on the computer, all I can get is a screen full of
> alternating rows of "@" (in inverse) and "?". Also , there is no beep
> from the speaker and CTRL+RESET does nothing.
> 
> Anybody can help me?

I have received a lot of very helpful replies. Now I want to summarize
what I did and how I managed to solve the problem. 
I hope this account can be of help to others.

1) With a digital tester I have checked the power supply and the dc
voltages on each chip. All were well within specifications.

2) Following many replies on this ng, I have pulled each chip out of the
motherboard, cleaning the pins to remove dirt and oxide, and putting the
chips back in. 
First, I have done this only on the smaller non-RAM chips, then on the
many RAMs and finally I have also cleaned the larger ROMs and the 6502.
Each time I have turned the A2 on to test its behavior. Nothing
changed... :-(((

3) I have managed to get a second A2 (plus several expansion cards and
two shiny original Apple floppy drives). Following a sort of "inner
feeling", I have replaced the 6502 on my dead motherboard with that on
the second computer. Wow, works!!!
Now my A2 first beeps at boot and then the usual prompt appears.
It was the processor (thank Andy!)

I'll buy a new 6502 for my second Apple. It really deserve to come back
to life! 
Thank again to everyone that helped.

Cheers

--
Sabino