[Coco] Caring for a CoCo

[Jim Hathaway]

Mark,

I was not aware of that issue.  This board does have very long leads and
when I insert it I do tend to push rather hard to make sure I seat it really
well, this might  be the issue then.  I will look into that, very good to
know.

My SIMM board is a wirewrap special and the wires are all over the place, so
cross talk is possible too.

Thanks,

Jim Hathaway
Web: http://hat3.net


On Thu, Nov 19, 2009 at 11:52 AM, Mark Marlette
<mmarlette at frontiernet.net>wrote:

> Jim,
>
> Might want to check to see how long the interface leads of the 512k are.
>
> I have seen ones that are too long and allow the 512k board to bottom out
> on the motherboard, cause shorts.
>
> There are traces that run under the CoCo's 512k expansion connectors and
>  the connectors DO NOT have a physical bottom or stop to them. Dumb, cheap,
> what ever you want to call it.
>
> I suspecting that your homemade version is a wire wrapped model or is it a
> PWB board? Depending on signal routing and crosstalk of other w/w wires,
> this will cause this erratic operation to occur.
>
> Mark
> Cloud-9
>
>
> ----- Original Message -----
> From: "Jim Hathaway" <kg4knb at hat3.net>
> To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> Sent: Thursday, November 19, 2009 9:15:32 AM GMT -06:00 US/Canada Central
> Subject: Re: [Coco] Caring for a CoCo
>
> On Thu, Nov 19, 2009 at 8:27 AM, Mark Marlette <mmarlette at frontiernet.net
> >wrote:
>
> >
> > Since the machine is apart. I would remove the GIME, with the proper
> > tooling, a PLCC chip removal tool, and clean the leads. Soft white
> eraser,
> > rubbed in the direction of the lead. This will ensure that you don't bend
> > the lead.
> >
> > Materials tarnish, sockets are a HUGH reliability factor. In defense
> > designs, we can't use them, nor want to for this reason.
> >
> > Not sure if you are using a multi-pak or not. Same applies here. Tandy
> did
> > not use gold on their card edge connectors in the multi-paks or in the
> > floppy controllers, 502 might have. My dev. system runs 24/7. Failure
> points
> > will be in the multi-pak OR cards that DO NOT have a gold card edge.
> Another
> > reason why ALL Cloud-9 products, that have a card edge connection,
> require
> > that surface to be plated with gold. Thus a higher cost, but higher
> > reliability = quality product.To clean the card edge connections, again
> use
> > the white soft eraser, it won't be white for long....... :)
> >
> > Mark
> > Cloud-9
> >
> >
> >
> Thanks for providing some more details around possible failure points.  I
> have been dealing with issues from my two CoCo 3 systems in the past year
> or
> so.  The first issue was the complete failure of a 512k memory board.  This
> one drove me crazy and I spent lots of time replacing all the memory chips,
> replacing caps on the board and also trying to re-flow the solder
> connections on the board.  All of these steps did not help, and so in the
> end there is something else that has caused this board to fail.  This board
> was manufactured by Performance Peripherals.
>
> My only working 512k board that is 'working' is a home made 512k simm
> board.
>  However when I use this board in either of my systems and attempt to use
> drivewire and boot into nitros I find that after a few minutes the system
> becomes unreliable, locking up, weird characters on the screen, etc.  I
> suspect the simms might be bad, but have not done extensive testing.
>
> At this point I am not even connecting my multi-pack to my system(s)
> because
> as you stated this is just another point of failure (all the connections).
>  I figure I should be able to take just a stand alone 512k CoCo 3 boot into
> nitros via drivewire and have a reliable system.
>
> Jim
>
>
>
>
>
> > ----- Original Message -----
> > From: "Boisy G. Pitre" <boisy at tee-boy.com>
> > To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> > Sent: Wednesday, November 18, 2009 6:00:45 PM GMT -06:00 US/Canada
> Central
> > Subject: Re: [Coco] Caring for a CoCo
> >
> > I would think that would be an issue with a lot of CoCos and might
> explain
> > some of the "strangeness" that CoCo's exhibit as they get older.
> >
> > What would be the symptoms of this type of degradation james?
> > --
> > Boisy G. Pitre
> > http://www.tee-boy.com/
> >
> > On Nov 18, 2009, at 5:19 PM, jdaggett at gate.net wrote:
> >
> > > On 18 Nov 2009 at 13:23, Mike Pepe wrote:
> > >
> > >> I would also consider changing out the electrolytic filter caps in the
> > >> power supply, as they do tend to dry out with age and the increasing
> > >> amounts of AC ripple riding through the supply can't be good for it.
> > >
> > > The electrolytics would only be a problem if the unit has sat for
> several
> > years and not been
> > > powered up. Yes the electrolytic materail tends to deform with age and
> no
> > charge on the cap.
> > > What happens then is the ESR of the cap goes way up. This reduces its
> > function as a filter
> > > against ripple.
> > >
> > > james
> > >
> > > --
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> > > Coco at maltedmedia.com
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> >
> >
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