Date   : Fri, 05 Jun 2009 16:42:53 +0100
From   : michael.firth@... (michael.firth@...)
Subject: Issue 4 will not accept a 1770

The quick reply was just because you hadn't mentioned S9, which was possibly
a quick win.

According to the instructions (which have some amusing typos!) at:

http://acorn.chriswhy.co.uk/docs/Acorn/Tech/Acorn_1770DiscIFUpgradeKit.pdf

you've done all that should be needed for an Issue 4 PCB.

I think the main thing to check next is that all the pins of IC78 are actually
correctly mating with the PCB - I've read of at least one case on this list
where one pin was bent under the socket, rather than going into the PCB.

Otherwise, its a rather difficult process to know what to do next, but if 
the DFS isn't starting up at all then it means that its not seeing the 1770 
module, so I would expect the problem is around IC78, rather than the ancillary
chips and links, which are 'disk side' of the 1770, and so not relevant unless
you can get the DFS to start up.

Regards

Michael
 

> -----Original Message-----
> From: 
> bbc-micro-bounces+michael.firth=bt.com@... 
> [mailto:bbc-micro-bounces+michael.firth=bt.com@...
> .uk] On Behalf Of Andy Ford
> Sent: 05 June 2009 16:08
> To: bbc-micro@...
> Subject: Re: [BBC-Micro] Issue 4 will not accept a 1770
> 
> Thanks for the quick reply :)
> 
> Yes, this was the first thing I did (cut the wire link at S9) 
> , tested 
> after I cut it actually to ensure it was definitely open.
> 
> I did actually mention this in my first composed email, but 
> Thunderbird 
> crashed before I could submit it, so I had to redo another 
> one, must of 
> left that line out of the things I have done by mistake.
> 
> 
> Andy.
> 
> 
> 
> michael.firth@... wrote:
> > You have removed the NMI link (I think its S9) haven't you 
> (it doesn't mention this in your message)?
> >
> > Regards
> >
> > Michael 
> >
> >   
> >> -----Original Message-----
> >> From: 
> >> bbc-micro-bounces+michael.firth=bt.com@... 
> >> [mailto:bbc-micro-bounces+michael.firth=bt.com@...
> >> .uk] On Behalf Of Andy Ford
> >> Sent: 05 June 2009 15:51
> >> To: bbc-micro@...
> >> Subject: [BBC-Micro] Issue 4 will not accept a 1770
> >>
> >> Hello.
> >>
> >> Just a bit of advice really :)
> >>
> >> I have here an Issue 4 'B. As far as I am "aware" , this has 
> >> always been 
> >> a tape only machine. However, I am unable to get a 1770 
> based DFS to 
> >> work in it. It's simply completely ignored.
> >>
> >> To confirm a few things first.
> >>
> >> The parts I am using (I have tried two different sets, one by 
> >> WE and one 
> >> by RetroClinic) , both kits function and are 100% ok in 
> >> another machine. 
> >> It's just this particular Issue 4 that does not seem to like 
> >> it for some 
> >> reason. As I say, all the kit parts do work in another machine.
> >>
> >> IC86 = Fitted a link
> >> IC87 = Fitted a link (as an extra note I did have a spare 
> >> 74LS123 that I 
> >> tried as part of my "testing" too)
> >> IC79 + IC80 = Fitted 7438's (tried the ones from the WE 
> machine too)
> >>
> >> The other links are set as follows (have not touched them)
> >>
> >> S18-North
> >> S19-East
> >> S20-North
> >> S21-2 x East/West
> >> S22-North
> >> S32-West
> >> S33-West
> >>
> >> I do not have enough spares lying around to try a 8271 based 
> >> interface 
> >> at the moment (yet) although I really only want the 1770 
> kit to work. 
> >> Yes, I did fit the ROM and the module (as I say, I have 
> two kits and 
> >> have tried each component in another machine and it all works 
> >> fine) , I 
> >> traced a few of the pins of IC78 and they seemed ok.
> >>
> >> It was suggested to me to replace the 7438 on the far left 
> >> side ( thanks 
> >> Mark :) ), this I did yesterday evening (after cursing 
> Acorn for not 
> >> fitting a socket here, I have done) , although it's no 
> better (I made 
> >> sure the socket I fitted was fine regarding continuity etc)
> >>
> >> Just wondered what the next sensible thing to test / 
> replace would be 
> >> really. I have a multimeter but I do not have an 
> oscilloscope so can 
> >> check a few things if directed. I do have a machine on its 
> >> way here via 
> >> Ebay to put this kit into but I'd rather not have this 
> >> machine in this 
> >> kind of "limbo" state if possible.
> >>
> >>
> >> Thanks :)
> >>
> >> _______________________________________________
> >> bbc-micro mailing list
> >> bbc-micro@...
> >> http://lists.cloud9.co.uk/mailman/listinfo/bbc-micro
> >>
> >>     
> >
> >   
> 
> _______________________________________________
> bbc-micro mailing list
> bbc-micro@...
> http://lists.cloud9.co.uk/mailman/listinfo/bbc-micro
>