Hello everyone,
Long time lurker and I've run into a problem, and that I can't google youtube, or read my way through. Maybe someone could offer help or give me a road to go down to fix this scope I just bought.
So I ran out and found a hp54201a scope from fleabay. It was supposed to be working, and of course the scope once I received it has some damage from poor packaging, and from rough handling from FedEx. So this scope once I turn it one, the screen immediately goes into "FATAL ERROR u38" So I did see that there is service manuals, and operator manuals on the net. But no where in the service manual did I see anything about fatal errors. doing the key down reset does not change things. Switching from protected and unprotected CAL doesn't change. Key down and power on doesn't change anything. Leaving it on for an hour and restarting doesn't change anything. I probed around the power supply and the voltages were in spec according to the service manual.
I even did a little detective work, in that if this fatal error code relates to a chip, u38 is some kind of waveform storage SRAM. and to my surprise the battery backup still provides a voltage to the chip. I even tracked down and replaced that one sram chip, verified the conections (in that the address pins, power and ground are good, with continuity and .1 ohms of resistance.)
But after replacing the chip, nothing changed, the scope still boots into "FATAL ERROR U38" My stabs in the dark aren't helping, and the service manual isn't helping with this issue. Any ideas?