DEC TU-80 Trouble shooting info

[Tony Duell]

> It turns on and when you push "logic on" it goes 
> into self test and just stays there with out any
> codes displayed. Display just stays at "00"
> voltages look close. DEC manual says system main
> board or voltages off.  I guess they just had a 
> stack of spare boards to test with. 

Again, I've never worked on one of these, so this is very generic 
information.

If there's a recognisable microprocessor on the controller board, I'd 
check it was getting a clock signal, that the reset line wasn't being 
held asserted, and then check that there was activity on the bus lines 
from said microprocessor. 

This might give you an idea of where to start looking for the fault.

-tony