The PDF of the printset came from here:
http://bitsavers.org/pdf/dec/qbus/MP02259_RQDX3_schem_Oct85.pdf
Look at p12 for the M5098, the component that is not working is E1,
specifically pin 3 is high and pin 4 is high, but pin 1 is high and pin 2 is
low.
Thanks, I'ev now looked at it. I understnad what it does.Looks like a
National DS8837 would work fine. I think a Signetics/Philips 8T37 would
do too (but I susepct that's really hard to find).
I checked the enable inputs too, pins 7 and 9, and
they are both low, which
looks correct to me.
Yes, they;re low to enable, high to disable. However, it's worth checking
all this.
Someone has offered me a couple of 8837s, but if I can
find a source of
equivalents I would prefer to buy those rather than use someone's spares.
I don;t think they're still being made by anybody, so you are going to
end up with a NOS part, in other words 'somebody's spare'.
-tony