HP54602b checksum error

[johndczerwinski]

Hi,
I have an HP54602b (150 Mhz/4-channel oscilloscope) that's now getting checksum errors and having lock issues with NTSC signals (see below and attached). 

Error messages:
"Vertical cal factors failied checksum test - defaults loaded"
"Horizontal cal factors failed checksum test - defaults loaded"

Doing some reading, it looks to be the NVSRAM chip, so I'm thinking of doing the following:
- Buying a new NVSRAM
- program chip with an RAM image I found on the Keysight page
- Open up the HP54602b, after discharging the CRT
- Un-solder old chip
- Solder new chip

Am I missing anything? Do I need to re-calibrate the entire device?

[nsd_c]

Just curious, where did you find a RAM image on Keysight's website? I don't have any actual vested interest, just curious. I have a 54621D, but this is rather different from the older 54602.

Also, I don't know if you've found this yet or not, but there are full schematics for the 54600 and 54601 in what HP called a "component level information package," available from here. (That link isn't actually working for me at the moment, but an alternative would be these scanned copies of the schematics.)

By the way, I have seen users report success in hacking batteries into the existing NVRAM.

[johndczerwinski]

Thanks for the information!

I got it from the Drivers, Software & Firmware portion of the support site a while ago.  Just looked and don't seem to be able to find it again. 

In case anyone else is looking for it, I've attached it.  FYI... It's for the HP54602A and not B