I also experience this failure-to-reset problem on my 7L5 (B09xxxx) when installed in the
7854 mainframe. However, the problem never appears when the 7L5 is installed in the
7603 or the R7603.
And now for something interesting: if I turn off the 7854, and then turn it back on
four seconds later, the 7L5 resets itself properly. But if I wait 8 seconds instead of 4,
the reset bug appears again. This is quite reproducible with my hardware.
I wonder if it is related to the R621/C621 RC constant...