Date   : Fri, 05 Jun 2009 18:05:02 +0100
From   : acorn@... (Andy Ford)
Subject: Issue 4 will not accept a 1770

Pete Turnbull wrote:
> I've had one like that.  A good way to make a reasonably good check is 
> to remove the board and just see if all the pins are apparent on the 
> non-component side.  Not 100% foolproof (I've had one socket where the 
> soldering was fine but the pin was actually broken between socket and 
> PCB) but pretty safe.  In the case of the broken pin, the symptom was 
> that things worked for a few minutes, but as the machine warmed up, 
> the expansion raised the socket just enough to break the connection!
>
>   A bit of a long shot, but are you sure the DFS ROM matches the rest 
> of the interface?  I seem to remember that some Watford ones expected 
> the FDC chip at a different address to Acorn's, but others didn't 
> (Solidisk did the same).
>
>   
* I may have sent a copy of this to your mailbox too as well as the list 
Pete, sorry!

Will carefully check those pins (from the component side to the next 
test point from following the PCB) , although that idea of making sure 
the pins are actually exposed on the solder side of the board is a good 
tip, thanks Pete. :)
 

 I'm certain the ROM's are fine, as I have a functioning WE 1770 board 
(the WE is an issue 1) in an Issue 7 B, that's the machine I         
used to test the newer components in too.

As another test, I also whipped the WE 1770 board out of the Issue 7 and 
tried it in the Issue 4, although it did not work.

I have 2x Acorn Roms and 1x WE DDFS (1.54T) rom (all work in the Issue 7 
with either 1770 interface and either chips (IC79 and IC80) . I also 
verified the links are actually connected too. So I was a bit stumped as 
what else to try after Mark's suggestion of changing the 7438 too) , 
hence a mail here for the other experts to suggest possible causes.

I need to sit down, whip the board out again and be 100% certain the 
socket is fine. :)


Andy.