[Coco] CoCo 2 Repair Help

Thu Aug 24 20:47:54 EDT 2017

My new RAM chips came in yesterday and I finally had time tonight to
desolder all the originals, solder in sockets, and pop in the new RAM.
SUCCESS!!  After it booted up with all 8 new RAM ICs installed, I used
process of elimination and found the just two of the original 8 ICs were
bad.  So, I've got lots of spares for future repairs.

So to sum up, the screen was putting random ones and zero on the screen,
wouldn't respond to commands such as SOUND or CLOAD, and would vary the
pattern when pressing the reset button.  Checking all the socketed ICs
showed that they were all good.  Final repair:  replace the faulty RAM ICs.

Thanks to the group for the advice!

On Tue, Aug 22, 2017 at 7:41 AM, Joshua Harper via Coco <
coco at maltedmedia.com> wrote:

>
>
> Sent from my iPhone
>
> > On Aug 22, 2017, at 6:29 AM, Frank Thompson <frank.thompson.iv at gmail.com>
> wrote:
> >
> > My Coco 2 is a 26-3127, I'm in Southeast Michigan (Livonia).
> >
> > On Mon, Aug 21, 2017 at 11:43 PM, Josh Harper via Coco <
> coco at maltedmedia.com
> >> wrote:
> >
> >> hi there
> >> may I ask what model is your coco 2also what state are you in
> >>
> >>
> >>      From: Frank Thompson <frank.thompson.iv at gmail.com>
> >> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> >> Sent: Monday, August 21, 2017 9:00 PM
> >> Subject: Re: [Coco] CoCo 2 Repair Help
> >>
> >> That is really interesting to hear!  I really was suspicious of the
> seller,
> >> and really thought that I was getting scammed.  I wasn't too worried
> since
> >> e-bay policies heavily favor the buyers.  I figured the worst I'd be out
> >> was some time and energy.  I was really surprised when I got back from a
> >> trip I was on and the computer was waiting at my doorstep!
> >>
> >> The first thing I did was to inspect the warranty label on the bottom
> and
> >> it was intact, so I thought I was good to go.  Later, I tried actually
> >> booting it up and then I realized it was a dud.
> >>
> >> I have my suspicions as well about these units.  I asked the seller why
> he
> >> sold the same computer three times (three completed e-bay auctions with
> the
> >> same pics) and he simply said he had a lot of these.  It makes sense if
> >> these were returns to the store, or somehow seconds.  I definitely got a
> >> different one than what was in the pictures in the e-bay auction though
> >> since the one I got had the actual (matching) serial number tag still
> stuck
> >> on the outside of the box.
> >>
> >> At any rate, the soldering doesn't bother me, I'm just bummed that I
> had to
> >> punch through that warranty label.  It is no longer a virgin system.  Oh
> >> well.  The case and keyboard are beautifully clean and white still.
> :)  I
> >> just hope it really is the RAM and not something else.  But honestly,
> there
> >> aren't that many more IC's on this thing, so eventually I'll get to the
> >> bottom of it.
> >>
> >> I'll have to read up on the yellow bars issue... that is a new one to
> me.
> >>
> >> On Mon, Aug 21, 2017 at 9:08 PM, Paul Shoemaker <paulfe3 at swbell.net>
> >> wrote:
> >>
> >>> Frank, good luck with the repair.  I hope you're able to get the
> machine
> >>> up and running.  I also purchased one of the new in box CoCo 2's from
> >> that
> >>> same seller in an earlier auction.  My CoCo 2 powers up and runs fine,
> >> but
> >>> has the dreaded vertical yellow bar on the hi-res screens.  I've seen
> >>> Zippster's article on how to fix this, but I am somewhat new to
> >>> soldering/de-soldering so I haven't gotten up the courage to try it
> yet.
> >>> I understand that the yellow bar is not terribly uncommon on CoCo 2
> >>> systems, but I am beginning to suspect that the seller has a batch of
> >> CoCo
> >>> 2 systems that perhaps did not pass the final quality check on the
> >> assembly
> >>> line way back when.  Seems like I recall seeing some feedback from a
> >> third
> >>> buyer whose NIB system did now work, as well.
> >>> -Paul
> >>>     From: Frank Thompson <frank.thompson.iv at gmail.com>
> >>> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> >>> Sent: Monday, August 21, 2017 3:26 PM
> >>> Subject: Re: [Coco] CoCo 2 Repair Help
> >>>
> >>> I appreciate the offer, but I'm comfortable doing this myself.  Once I
> >> get
> >>> the new RAM in the mail, I'll install it and post up more results.
> >>>
> >>> Thanks for the advice and help guys!
> >>>
> >>> On Mon, Aug 21, 2017 at 4:11 PM, Bill Gunshannon <
> >>> bill.gunshannon at hotmail.com> wrote:
> >>>
> >>>>
> >>>> ________________________________________
> >>>> From: Coco [coco-bounces at maltedmedia.com] on behalf of camillus gmail
> >> [
> >>>> camillus.b.58 at gmail.com]
> >>>> Sent: Monday, August 21, 2017 2:31 PM
> >>>> To: Bill via Coco
> >>>> Subject: Re: [Coco] CoCo 2 Repair Help
> >>>>
> >>>> Hallo zipster,
> >>>>
> >>>> If you need some help, i can socket all your ic's.
> >>>> I have done more then 7 cpu socketting and had never one dead.
> >>>> i even manage to save some of the old cpu's
> >>>>
> >>>> All you need to do is send me the board, with return label and the
> >> needed
> >>>> ic sockets ( I use the machined ones, more expensive but way better
> ).
> >>>>
> >>>> Oh and I do this freely.
> >>>> cb
> >>>>
> >>>>
> >>>> ________________________________
> >>>>
> >>>> And I can tell you he does a really good job, too.
> >>>>
> >>>> bill
> >>>>
> >>>> --
> >>>> Coco mailing list
> >>>> Coco at maltedmedia.com
> >>>> https://pairlist5.pair.net/mailman/listinfo/coco
> >>>>
> >>>
> >>> --
> >>> Coco mailing list
> >>> Coco at maltedmedia.com
> >>> https://pairlist5.pair.net/mailman/listinfo/coco
> >>>
> >>>
> >>>
> >>>
> >>> --
> >>> Coco mailing list
> >>> Coco at maltedmedia.com
> >>> https://pairlist5.pair.net/mailman/listinfo/coco
> >>>
> >>
> >> --
> >> Coco mailing list
> >> Coco at maltedmedia.com
> >> https://pairlist5.pair.net/mailman/listinfo/coco
> >>
> >>
> >>
> >>
> >> --
> >> Coco mailing list
> >> Coco at maltedmedia.com
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> >>
> >
> > --
> > Coco mailing list
> > Coco at maltedmedia.com
> > https://pairlist5.pair.net/mailman/listinfo/coco it's possible that I
> might have a motherboard that actually works if you'd be interested in it I
> don't have to see though I'm not 100% sure I still have it but if I have it
> I could send it to you and it wouldn't cost you anything other than maybe
> about six dollars in shipping
>
>
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