UPDATE:
After must effort i have some answers on the NVRAM chip and how it's used and configured in the WFM601 Waveform Monitors and what it all means...
What NVRAM is used?The NVRAM used in these waveform monitors is a Dallas DS1643, it's a 8k NVRAM with clock, the DS1643 is no longer available but ST Micro make an alternative in the M48T08.
What's stored in the NVRAM?The NVRAM stores the model, serial number and calibration data for the monitor, although some adjustments are made with physical adjustment pots most adjustment is made with software and stored in the NVRAM.
What happens when the NVRAM goes flat?When the battery goes flat the Monitor will no longer boot and will report 'CONFIGURATION ERROR CONTACT TEKTRONIX SERVICE'
How do i fixed a monitor with a flat battery?Step 1:You will need to remove the old one and replace it or perform a battery hack to remote locate an external battery onto it.
Step 2:Using the UPGRADE.EXE software running under DOS or the Windows98 command prompt in DOS mode you need to configure the NVRAM with the correct model, serial number and date. A RS232 cable is also needed between your PC and the monitor.
To do this type:
UPGRADE -C
This will clear the NVRAM and configure it enough to boot. But it will be completely un-calibrated, although you will be able to see everything working
you will find much of it will be so far out of specification it's essentially unusable as a reference instrument!!Can i re-calibrate the monitor?Yes it can be re-calibrated but it does involve 100s of steps and a very good selection of electronic test equipment (oscilloscopes, signal generators) and broadcast test equipment (SDI test pattern generator).
I have a working monitor, can i make a backup of the NVRAM?YES! Using the UPGRADE.EXE software running under DOS or the Windows98 command prompt in DOS mode, A RS232 cable is also needed between your PC and the monitor.
To backup typeUPGRADE -S
To restore typeUPGRADE -R
Can the original Dallas be battery hacked so i don't need to remove it?Yes it can be battery hacked if you want to keep the original and save yourself some £/€/$. The battery is located on in the potting compound slightly to the right hand side of the device.
Is there any official documentation on all this?Yes, all software and documentation is attached file with the exception of the service manual which is easily available online (it's too large to attach here)