Whats going on with this A500?

[Franko]

Also, with regard to the C64's - the 2 non functioning ones seem to have chips missing although I can't tell if it would be the same chip or not as one is a 64C. Can anyone point me to someplace that might help me identify the missing chips?
Thanks!

Can't help with that weird setup on the A500 but if you could post some pics or open up the C64's and tell me what chips are missing by identifying them from their component reference numbers printed on the motherboard, I'll be able to tell you which chips are missing as I have the Commodore C64 service manuals and all the different models of the C64 myself...

[Franko]

missing C64 chips: from C64C - U9, from breadbin C64 - U18

U18 = 6581 SID Chip : Commodore Part Number "C 906112-01"

U9 is a bit more difficult to tell you what that is as the service manual covers 3 different motherboard revisions and of the four C64c's that I have unfortunately none of them are covered in the service manual...

All I can tell you about U9 is the following...

According to the service manual for the following motherboard revisions U9=

MB REV 326106 / 251138 & 251469 then U9 = 4164 (200 ns) (RAM CHIP) Commodore Part No "901505-01"

On My own physical C64c's...

MB REV 252311 then U9 = 8580RS

So apart from U18 being the SID Chip, U9 can be any of the above until you check which motherboard revision you have by opening it up...

Hope this helps...

[Franko]

I've used the photo from the link RobertB supplied to point out where U9 is on my C64c's as the photo is of the REV 252311 board and if yours is this version the U9= 8580RS