Date : Sat, 06 Jun 2009 12:03:32 +0100
From : acorn@... (Andy Ford)
Subject: Issue 4 will not accept a 1770
Thanks to everyone so far for help and advice.
I verified via *FX that the roms are identified (they were) , although
as I say none of the components fail in another machine (I have two 1770
interfaces)
I had an hour this morning so I whipped the board out and tested the
following...
1. Visual inspection on solder side of board to check all pins are
present (all ok)
2. Checked continuity between socket side and solder side (all ok)
3. Carefully checked for continuity between each socket pin (component
side) by following the tracks one at a time to the nearest suitable test
point / component along the board (so at least I know the socket is
wired ok to other components)
Not sure what to try next really, I do have something else I could use
this machine for and have one that should arrive via Ebay in a few days
which will become the new "home" for this kit. Just a bit unfortunate
(typical for me) that the machine I had dedicated for this has this
fault. Oh well. :D
:)
Andy.
Mark Haysman wrote:
>>> 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.
>>>
>> Have you checked the machine is 'seeing' the ROM? Does another ROM work
>> in that socket? I've had one iss4 machine with very dodgy ROM sockets in
>> the past.
>>
>> While 1770DFS doesn't start up if it can't see it's controller, it
>> wouldn't be too hard to write a bit of BASIC read the first few bytes
>> from the ROM to check it is actually there.
>>
>> I'd also check the /CS line on the FDC is being driven correctly (ie.
>> the address decoding is working) tho this really needs a scope.
>>
>
> You can check a ROM is being seen by forcing it to do a language startup, if
> the ROM is in the socket next to the OS for instance, a
>
> *FX142,12
>
> Should give a short message identifying the ROM, although it will crash the
> machine. 13, 14 and 15 are the next ones alog.
>
> As for the Watford DDFSs, V1.54T is compatible with the Acorn boards (and
> mine), and uses the DDB3 PCB, all (?) earlier versions use the DDB2 board,
> and have things located differently.
>
> Mark.
>
>
>
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