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Final update: Received a new FPU today (from a local dealer) - it works as expected. The Mac was innocent   [:)] (Sorry for having opened this topic, I just could not believe that a package of 5 FPUs contains only dead ones)

With some more testing, i.e. in other boards and on a network card, the conclusion is that the FPU(s) are dead. I excluded hypothesis this so far because I bought a package of 5 and they all cause the same problem. Yes, I bought them on ebay, they were coming from China and they have already...

Here is the exact testing acitivies: 1) Power supply is not connected to the board: infinite resistance between Pin 9 (GND) and Pin 61 (VCC) of the FPU socket 2) Power supply connected to the board (NOT switched on): 0 resistance for 1-2 seconds, then infinite (same pins) 3) Lift one probe...

Ok, this link is helpful, thanks. Apparently I have to have a much closer look on the board. So far I was assuming that the transport or the replacement of battery were the cause of the issue.

Hi bibilit, I have not yet down anything with the Mac - as said when I took it out of the parcel it was refusing any cooperation. So I have not seen the Mac running. The board looks neat and clean, and the sender confirms (more or less precisely - that the Mac was working before she sent if...

Update: Yesterday I checked the FPU clock pin (socket) with my scope: The 33MHz clock speed signal is is available and proper. Then the CPU also receive the clock speed signal and should be running. Next I will check /HALT and /BERR  Is it then correct to assume that the PRAM is ok and my...

Thanks for the feedback so far. Sorry for not having mentioned the obvious: Yes, I have cross-changed all components (PSU, battery) and did the PRAM-reset command I have checked the FPU-Pins  and I have checked the socket-Pins. I have also checked the board for dust or anything that could...

@Bolle: I was very careful in inserting the FPU - it was correctly done @superjer2000: hmm yes, ebay and China and already thought about that, but I bought 5 and they all behave the same - see below. But: VCC connected with GND on the FPU-socket is much more critical: I compared it with my...

I meant VCC and GND is shorted ON SOCKET as soon as the power supply is connected.. The FPU does not show any shortages and I tested with several FPUs. 

Hi everybody, I received recently a P460. The sender affirms that it was working fine before it was sent off, but she is not expert and her statements are not very precise. Last thing she said she did was replacing the dead battery and taking out the harddisk. Starting the Mac here: no chime...

Hi everybody, I have here a Performa 450 in which recently I wanted to install a FPU. (CPU is an overclocked 68030-16, FPU is 68882-33) With the FPU installed the P450 is completed blocked, not even the initial chime, and the PSU is "ticking". I finished by checking the pins of the FPU...