Date   : Fri, 14 Aug 2009 21:00:17 +0200 (BST)
From   : johan@... (Johan Heuseveldt)
Subject: econet bridge protocol

Hi,

One sad, one joy...

On Tue 04 Aug, Johan Heuseveldt wrote:
> On Mon 27 Jul, Johan Heuseveldt wrote:

> > Update...

[ net 1 - Acorn bridge - net 2 - SJ bridge - net 3 - Acorn bridge - net 4 ]

> > More concern was one of the Acorn Bridges; It was dead. It turns
> > [...]
> Although ordered, later I found the DIL variants. This was a
> [...]
> I should receive the line drivers at home in about 14 days,
> as they're coming from abroad. That's the end of next week.
> Fingers crossed!


The sad...
~~~~~~~
Arrived! But;
Both damaged line drivers are AM26LS30; '30' for short. Replacing
both with a new one, didn't work as aspected though. In the end I
needed a '30' for IC14, and  a '34' for IC16, just as in the other
bridge. Both bridges are the same with a PCB of '0237,000 Iss.2'.
There are no modifications found on both of them, including back side.

Within 5 seconds after powering up, IC16 is too hot to touch. At
first I didn't notice, and for 20 minutes or so, the bridge was on.
When used in the 'good' bridge, the chip was still functioning!
OK, the data sheet say they have Short Circuit Current Limit, but it
can not last for ever!

Please note that the actual line drivers are in IC 14, closest to
the Crystal. This IC 14 is used as

  Dual Differential Line Drivers  (EIA-422-A)

and each one is driving the net data on their nets A and B.

The other one, IC 16 and closest to one of the 68B54, is used as

  Quad Single Ended Line Drivers  (EIA-423-A)

and this makes several connections between the two networks, as
reported a while back. :-)
Perhaps some diagnostic or test hard ware?

It seems to me that these '30' ones are not the same as they used
to be, and IC 16 can no longer be such one. Instead, it must be a '34'.
The Dutch person, who responded earlier, also confirmed this similar
situation.



OK, I've asked my supplier if the '34' can be delivered? Yes it
can, but at a cost of very close to 15 Euro. Minimum number to be
taken is 10. Is this normal? Is it made of pure gold?

Frankly, I'm not sure what to do.




The joy...
~~~~~~~
Three weeks back I 'discovered' a new shop in town. Mainly a repair
shop for Audio and Video equipment. This week it was opened again,
after holidays. I asked for Y-pieces or Y-cables. Soon he had the
Y-cables on screen, and I ordered a few.

This morning I got a call; they had arrived! So, this afternoon I had
a play with them. They seem ok. Perhaps a bit more picky on proper
termination.




Phil,
~~~~
was this of some use? Or was it something already familiar to you?

> The following was monitored from net 3, when the bridge between
> nets 1 and 2 was switched on:
> 
> 
> FFFF1818809Cv02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i
> FFFF3030819C03v02 i



Greetings,
Johan

-- 
Johan Heuseveldt <johan@...              >
  aka  waarland

  The best place is a Riscy place

The chief cause of problems is solutions.