ENA 5071 C not booting.

[rtekal]

Hi,

I have a E5071C ENA which fails to boot. The fans are running, No display on either internal or external display.  The power supply voltages are good and the voltage LED's are lit up in both boards.The service manual says the cause could be either the DSP board or the digital motherboard and has to be replaced.
There are two 7 segment displays at the corner on the digital motherboard, with POST code marking, and the code 6.2 (or b.2) is displayed. There is no description of the POST codes in the service manual. I have tried reseating the CPU and DIMM module on the motherboard.

Anybody having faced and resolved the same issue or have any service info.

Regards

[DaJMasta]

Can you identify the brand of the motherboard or BIOS?  Usually post codes are at least somewhat consistent between models, so it could give you a hint.

If I were to guess, it has nothing to do with your DSP board, this is just a PC problem.  These network analyzers are a regular PC that after booting to the OS it starts the software that talks to the network analyzer hardware, so you likely wouldn't see any error with VNA equipment until you're loading that software unless there's a dead short in a module pulling an important power supply rail down.

If you still suspect it, you could try disconnecting the interconnect cards as the PC portion should be able to boot on its own as a normal PC without them, but I suspect the problem would persist in such a test.

[rtekal]

 Looking at the images in the service manual, the MY461 series serial number has a standard motherboard. The MY462 and MY463 series have different motherboards with plugin CPU and DIMM memory module.

This instrument has a MY463 series serial number.The mother board is not the standard type. Looks like a proprietary motherboard. There are monitoring points and LED's for various voltages. This is the variant in which the CPU and DIMM memory are on a single plug-in assembly. The Agilent logo is etched on the motherboard and the BIOS has a agilent part number.

If I disconnect the DSP board, the instrument does not power on. Same is the case, If the interconnecting cables to the RF deck are disconnected. The instrument powers up even without the CPU and DIMM module. The POST code displayed 0.0. I put back the CPU & memory module with the RAM removed, the POST code changed to 1.5.