aclo dclo (11/45) flustered-ness

[Gooijen, Henk]

> Jay wrote....
> I got +5v & GND for my logic probe from CA2 & CC2 and powered 
> up just the BA11K. BF1 & BF2 both showed low as I'd expect 
> (since the cpu was powered off). This was a sanity check on 
> my part to make sure AC/DCLO were pulled low. I powered up 
> everything and BF1 & BF2 went hi. I hit load on the RL02 and 
> the drive started to spin up. At just the time I'd expect the 
> heads to load, the fault lite came on. BF1 & 2 were still hi. 
> If the RX02 is powered off, the drive will not fault, it will 
> spin up fine. Also, if the RX02 is off and everything else 
> on, the drive loads fine and boots RT11. The moment I plug in 
> the power for the RX02 the RL02 immediately faults (but the 
> cpu keeps on running right where it was). One thing I need to 
> check, I am not positive (because it's all rather loud) that 
> when the RL02 faults that it spins down the drive. I don't 
> recall hearing the noticeable decrease in volume. I would 
> have thought it would spin down upon any fault. Maybe it is 
> and i just didn't hear it.
> 
> I can start going through the prints on the RL02 as Tony 
> suggested, looking at all the signals that can trip the fault 
> light. Is that the right approach? I mean, the problem 
> obviously isn't in the RL02 or controller - as they work 
> flawlessly if the RX02 is turned off. This would make me 
> think the problem is more likely something about the RL02 or M8256.
> 
> At least I'm learning a lot :)
> 
> Jay 

Ooh, you're not the only one who is learning :-)
ACLO and DCLO are for me also signals to check. Tony pointed me
out that DCLO might be asserted by a (defective) memory board that
fails to initialize ... it was indeed that board that kepy my 11/84
from starting!

You can work your way back from the signal that drives the FAULT
lamp on the RL02. Perhaps an other approach is to check what signals
go from the RX02 drive to the M8256 RX211 controller.  Especially,
where the signals from that flatcable go on the RX211 module, and
what effect they might have on the UNIBUS. Perhaps there is a short
in the flatcable between the RX02 and the RX211 that acts up when
the RX02 is powered?

  good hunting,
- Henk.



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