Hi emanuel,

Thanks for the interesting information.  I'm going to try this again
this weekend.  

> 
> They are hidden in the black plastic, which hides the tacho too. you
> probably see the brown flexible pcb/wire, which connects to them. (one is on
> the top of the main pcb, the other on the other side.) Be carefull, while
> opening & cleaning the tacho !

> I started with 4 broken Tk50s, guess how many working I have now ;-)

I don't know, 0?  or 4?

> I have no clue, how much you know about the q-bus, but probably you put the
> TQK70 on a wrong position on the bus ? (behind a RQDX3, left some open bus
> slot, ...)

OK, I'll try moving it around.  But what I did was put the TK70 
controller where the TK50 controller had already been sitting.

> 
> > But when I try to read it,
> > I get all sorts of mag tape hardware errors, including a message
> > about the tape being read-only.
> 
> It seems, that you simply don't get interrupts from yout TQK70 ...

Yes, but remember, it does work fine with a KA650 in BA213 chassis.

> > Any clues would be appreciated.
> 
> Tell us, how the system looks like, which couldn't handle the TQK70.
> (enclosure, which cards on which place)

OK, I need to get the machine in front of me again, but I'll follow
up on this.

Thanks,

Doug