Looking for some advice.
I have an Apple IIe which is completely dead.
I have tested what components I can and found 3 faulty logic chips, 3 faulty ROMs and a suspect CPU. I replaced all of these , but still can't get any video output, nor do I get a beep with Ctrl G.
I have checked the clock which is OK, but the CPU reset doesn't seem to be working properly - a scope on Pin 40 of the CPU shows a high signal with a fair bit of noise and this doesn't go low when the reset key is pressed.
According to my understanding of the circuit, the most likely component to have failed is the Input/ Outpu Unit IC which in this machine is a 344-0022A (though the board is marked 343-0022), but I can't find a decent schematic to be sure I'm not missing something obvious.
Unfortunately I can't find a supplier for this chip (I'm in the UK), so would appreciate any tips as to where to obtain one, or help in diagnosing the real problem if I'm wrong about this chip being faulty.
I should add that I've tested all the RAM and that is all good.
Thanks for any help.