ECU7 PCB layout

[Al Lipper]

Dominic,
	You have some good questions.  First, the gerber files specify the width of
each trace and pad as an aperture.  This means that the outlines you are
getting is a result of some setting in the gerber viewer you are using, and
not in the file itself (I tried the file with two other viewers and traces
were filled).  Next, there are a number of errors on the PC board.  First,
look at the new schematic for changes to the optoisolator circuits, fuel
pump driver, stepper motor enable and the orientation of the DB-25 connector
(P-2).  Next, there is an erroneous short between two traces going to the
driver transistor for injector #1 (Q1, I believe).  This trace should be
eliminated.  Next, on the CPU board, there is a problem with the RD and WR
lines being connected together and run as a single trace to the support
chips.  The schematic is correct, but OrCAD did something unusual when it
created the netlist, so these were incorrectly indicated as a single
circuit.  Also, the holes for the inter-board connector (P1) are slightly
small.  Otherwise, the boards are overall correct.  BTW, all of the ground
signals do get connected together at one point.  Also, I am using an 18"
ribbon cable between the boards with no problem.  Over the next month or so,
we'll be revising them.  In the meantime, these corrections should take care
of most major issues.   BTW, I have a pair of them running relatively well
at the moment.   Good luck.


			Al


-----Original Message-----
From: Dominic Baker [mailto:dombaker at totalise.co.uk]
Sent: Saturday, February 05, 2000 12:42 PM
To: efi at cardozo.org
Subject: Al Lipper ECU7


Dear Al, I mailed u a couple of weeks ago about sending the ECU7 pcb etching
traces in an alternative format,  well that is no longer a problem  There is
a great Free Gerber viewer, with complete printing, saving and editing
facilities on the Lavenir web site, the viewer is called "Viewmate6.1" if
you want to pass that on to anyone else.

Anyway I am ready to make the boards up at university, I had a word with the
head of electronics but unfortunately he is not prepaired to make up any
number of these boards, but he will do a one off for me, I asked him because
I saw you were having trouble with the small batch prices.

I have but a couple of problems,  One is that ECU7B(injector controller
board) Top view the pads are fine, but the traces are double outlined
instead of filled, the viewer I have cannot change this back, but I can edit
them by hand as there are not too many of them.  Before I do this, are there
any newer later updates to the schematics/PCB boards I should know about
before I commit to these boards being made?  This board also has a problem
around the fuse and the two relays, which is quite confusing.  Being as I am
redrawing the traces this is a grey area that needs clearing up.

The other question I have is about the earths.  There are many of these and
several types eg, GND,DGND, ChassisGND etc.  I have all the drawings
including the component overlay(silkscreen) on transparancy so I can look
through the boards to trace the paths to check for any errors.  A lot of the
earths are clustered together with a track, but nothing joins these to the
actual GND.  Do the two boards have to piggy back a short distance apart
with pins joining the earths batween the two boards?
    Or do all the GND's have to be connected to say a metal box which is
earthed to the chassis?
Or even Connect a wire between all like earths, then connect that to the
chassis?

I apologise for this long and teadious email but If I can clear these small
problems up then I can start making the ECU7 efi, straight away.
Your help would be kindly appreaciated
Yours hopefully Dom Baker
Thanks


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