Looking for a M8330 or a couple of SN74194's

[Tony Duell]

> 
> Hi
>   Its not test gear that's the problem its access to the board. My Tek
> 465 will trigger on single pulses with no problem.
> However whilst it's recommended that the the first CPU board (the 8330)
> be in slot 2 (The front panel is in No1) its not mandatory. So I can
> move the boards back a bit and get to the front of the 8330.

All Omnius slots are the same, and in an 8/e backplane, AFAIK all slots 
are plain Omnibus.

The only time the top connectors are used on the M8330 is if you have the 
EAE board set installed, I think. If you do, take it out for the moment 
(you don't need it when trying to sort out a timing generator problem). 
You can then put the M8330 in whatever slot you want.

An extender board is useful, but by no means essential :-).

Another trick that's worked for me in the past if I can't re-arrange the 
boards and don't have an extneder is to solder a hnadful of wires to 
useful testpoints on the board and put it back in the cardcage. Then 
probee the free ends of the wires (make sure they don't short to 
anything!).  Normally 2 or 3 iterations of doing that will get me to the 
faulty chip.

> 
> Manual I have, (very good) Schematics also (Awful) so bad I may even
> redraw at least the 8330. I have an A0 HP plotter so its easy to do
> drawings.

DEC scheamtics have the odd error on them (I've heard it claimed said 
errors are deliberate, either to stop the machine being copied, or as 
copyright traps on the diagrams themselves). They're also somewhat 
unconventionally drawn (flip-flops may appear to have 4 outputs!), but 
I've got used to them. I must say that if I need to re-draw a sechematic, 
I use pen and paper, not a CAD system...

-tony