Now as you can see from the pictures, there are two chips missing/removed from the mobo. My question is, can i still start(power on) this mac without the MacMemory RAM board? ... Does anyone knows where can I get those missing chips and original 128k RAM chips? I hope to really restore this mac to its original components.
More than two chips, I count four. And no the board will not power on with those chips missing. It won't hurt anything to try, but it is unlikely.
That's going to be a substantial job to restore the logic board, and it will never be original condition. Your best bet is to start looking for a new one. The really sad part is for those missing chips, they've placed sockets, but not for the new RAM.
Very interesting RAM chips by the way - never seen any like them before.
The chips you are missing are easy to replace without any soldering as they will easily socket right in. I am a little concerned about those strange single and double pin sockets at D3, E3 & F3. Do they merely tap into the traces? Or have the traces been severed? The biggest repair you will have is the 7-pin socket at E3. This is where the mini-multiplexer was typically installed to upgrade 128K boards to 512K RAM. It required the board to be physically modified. Look underneath and you will see traces have been physically cut. Possibly at other locations on the board too considering some of the strange sockets. Otherwise, it is typically left empty for a 128K. G4 & F4 are simple resistor arrays like the one at E3. E12 & E13 are identical LS244 chips, which you will see mounted directly above the sockets on the RAM board. I wonder if these were actually removed from the Mac and used on the RAM board?
Note you have the aftermarket resistor array added to D15. This was added to the logicboard in any repair to the 128K to prevent a certain kind of lock-up. It is rare to fins a 128K without this added. And, it was mandatory in a 512K RAM upgrade. This might explain why the board was upgraded and the analogue board still has its upper heat sink fin. On the other hand, it could also be that the logic board is not original and one that had already been prepped for the RAM upgrade and merely swapped for the customers in a quick exchange. Anybody know how common that kind of thing was? The 68000 chip is typical of much later Macs, not one as early as this which would still have the the metal square on top.
There is some good news though. If you intend to merely operate the board as a 128K (not restore it), with the missing chips replaced, severed traces mended, and without any additional circuitry in the D3 location, I understand the additional RAM will not be recognized by the Mac, and the board even with 512K RAM installed, will operate normally as a 128K board. It has always been my intention to find a key connection in a 512K upgrade so install a switch that will simply engage or disengage the circuitry depending on how much RAM I want to use.
There's a thread about that somewhere, including one about toggling between 64K & 128K ROMs too. Just never got around to investigating it and didn't want to risk damaging anything without more details.
I have no idea if the 128K SIMMs work with any Mac.
Anonymous Freak –
check this out regarding 128K SIMMs.