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I have just assembled a Series 90-70 system and the CPU’s OK LED is off. I have replaced the CPU and the problem persists. What could be wrong?

November 28th, 2018

The most likely cause is that the rack that the CPU is located in is not configured with the proper rack number. The rack that contains the CPU should always be set to Rack 0. Any other setting will result in the CPU’s OK LED being off. To check the settings, disconnect power from the power supply and remove it from the rack. In the upper left-hand of the rack, there are several jumpers that are used to assign a rack number to the rack. (Refer to the manual GFK-0262 for a diagram of the jumpers.) Set the rack number to 0.

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