Hi Group,

I've got a 54540A in need of repair. This is a 4
channel 500 MHz digitizing scope of the generation
before Infinium. When first turned on it appears that
nothing happens. But it is alive to the degree that it
recognizes if you hold down a key during power-up,
which is the signal to prompt for a firmware update.
In this case a prompt appears on the CRT, and you need
to confirm with another keypress if you really want to
read in new firmware. If I press another key (even
though I don't have a new disk for it), then it
appears to go dead again.

I have checked all the power supply voltages and found
everything in order. My theory is that some part is
failing the power up self test early in the sequence,
and it is not able to display an error message at that
time. HP service consisted of exchanging keyboard or
main board assemblies, which would be determined by
swapping in a known good one. A replacement assembly
would probably be too expensive even if they had one
available.

Before I write this off ... does anyone know how to
access any further diagnostc info, or if there are any
specific things that I could check and possibly repair
to fix this ?

Geo.