Hello Dears,

I have a CPU 400. When I connect the CPU and power supply to the rack, The CPU does not turn on, which means that none of its led lights turn on, and I cannot to connect by PC. I tried with another CPU, which turned on and showed that the problem is not with the power supply.

I think it is because of the firmware. Is my guess is correct?

If you have any suggestion to solve my problem, Please help me.

Hello,

If it were a firmware failure, the CPU would start up.

My guess is that it must be a hardware failure of the CPU.

Thanks you

thank you for your answer,

What hardware problem could it be?

I checked the some component on the board of cpu, they have voltage, It shows that the voltage reaches them. 

Hello,

you should contact the repair center

Thanks you

pobasmary

Hello Dears,

I have a CPU 400. When I connect the CPU and power supply to the rack, The CPU does not turn on, which means that none of its led lights turn on, and I cannot to connect by PC. I tried with another CPU, which turned on and showed that the problem is not with the power supply.

I think it is because of the firmware. Is my guess is correct?

If you have any suggestion to solve my problem, Please help me.

 Hello,

Your guess regarding FW version is not correct. Because If it is correct, Siemens should let the CPU power up to allow you to make a FW update.

You lost powering of the CPU and accordingly communication with it.

In 2nd post from your side, you told that you checked some components and you found some of them have voltage. Actually, that means only that the CPU power circuit is partially working. Only Siemens who knows the their circuit and only Siemens can repair it for you.

Hope this helps.

Thank you for your answer.

I read from one of the Siemens documents that if the CPU is out of reach, 

what does this mean?