[Coco] Weird CoCo3 problem...

Mike Pepe lamune at doki-doki.net
Mon Jan 4 11:39:49 EST 2010 

You know, I was also thinking that maybe a bad power supply could be to blame here.

My spam filter got screwed up, I think I missed some list messages. Any updates on this issue?

> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-
> bounces at maltedmedia.com] On Behalf Of Mike Pepe
> Sent: Saturday, January 02, 2010 9:35 AM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] Weird CoCo3 problem...
> 
> I've never seen this particular issue before, but from what you describe the
> only thing I can think of is the SCS signal is not making it into the cartridge
> itself. I wonder if a different I/O pak such as the RS232 pak is functional on
> this system or not.
> 
> 
> 
> 
> > -----Original Message-----
> > From: coco-bounces at maltedmedia.com [mailto:coco-
> > bounces at maltedmedia.com] On Behalf Of Brian Blake
> > Sent: Saturday, January 02, 2010 6:05 AM
> > To: CoCoList for Color Computer Enthusiasts
> > Subject: Re: [Coco] Weird CoCo3 problem...
> >
> > Hi Mike,
> > The answer to both of those is 'yes'.
> >
> > I tried Tetris and it worked fine.
> > I also tried the POKE on the CoCo3 with the C9 512k upgrade and the
> > Drive 0 light did come on.
> > --- On Sat, 1/2/10, Mike Pepe <lamune at doki-doki.net> wrote:
> >
> > From: Mike Pepe <lamune at doki-doki.net>
> > Subject: Re: [Coco] Weird CoCo3 problem...
> > To: "CoCoList for Color Computer Enthusiasts" <coco at maltedmedia.com>
> > Date: Saturday, January 2, 2010, 2:10 AM
> >
> > 15KHz sounds about right for a loop like that. Every poke to that
> > address should drive SCS low momentarily.
> >
> > Two other things come to mind for checking- if you put this
> > controller/drive on another machine, does the poke make the drive
> > activity light come on? Second thing is- do any other cartridges work
> > on this machine? Any game paks to test with?
> >
> >
> > > -----Original Message-----
> > > From: coco-bounces at maltedmedia.com [mailto:coco-
> > > bounces at maltedmedia.com] On Behalf Of Brian Blake
> > > Sent: Friday, January 01, 2010 9:08 PM
> > > To: CoCoList for Color Computer Enthusiasts
> > > Subject: Re: [Coco] Weird CoCo3 problem...
> > >
> > > Hi Mike,
> > >
> > > Here's what I did - not sure if it was correct:
> > >
> > > 10 POKE &HFF40,1
> > > 20 GOTO 10
> > > RUN
> > >
> > > I then checked pin 6 of IC9 - which according to my schematic is the
> > > /SCS line - HI reading on my DMM in logic mode (<1 = LO, >2 = HI, in
> > > between it shows the voltage).
> > > I then checked pin 40 on the 6809 - the /HALT line - and got a
> > reading
> > > of 1.545vdc.
> > > Not sure if my DMM would react fast enough, I changed to Frequency
> > mode
> > > and checked pin 6 of IC9 again - got a reading of about 15-kHz.
> > > I hit the break key and checked pin 6 again, and it was still HI.
> > > Shut of the CoCo, waited a few seconds and turned it back on,
> > > checked again and it was still HI.
> > > Checking pin 36 on the slot yielded similar results, except the
> > > frequency was very different ~110-kHz.
> > >
> > >
> > >
> > > ________________________________
> > > From: Mike Pepe <lamune at doki-doki.net>
> > > To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> > > Sent: Fri, January 1, 2010 9:45:14 PM
> > > Subject: Re: [Coco] Weird CoCo3 problem...
> > >
> > > I'd put that POKE &HFF40,1 into an endless loop and look to see if
> > the
> > > SCS line on the cartridge port is stuck high or if it pulsates.
> > >
> > > Radio Shack used to sell a pretty decent logic probe for about $20.
> > Not
> > > sure if they still do, but it would help diagnose the problem in
> > > this case.
> > >
> > > The latch at $FF40 should function independently of a blown out 6809
> > > HALT line which is what usually indicates a CPU replacement.
> > >
> > > > -----Original Message-----
> > > > From: coco-bounces at maltedmedia.com [mailto:coco-
> > > > bounces at maltedmedia.com] On Behalf Of Brian Blake
> > > > Sent: Friday, January 01, 2010 4:48 PM
> > > > To: CoCoList for Color Computer Enthusiasts
> > > > Subject: Re: [Coco] Weird CoCo3 problem...
> > > >
> > > > Nope - no logic probe. What kind of signal should be seen there?
> > > > My
> > > DMM
> > > > has some logic functions built into it, but, I'm not sure off hand
> > > what
> > > > it's capable of...
> > > >
> > > >
> > > >
> > > > ________________________________
> > > > From: Mike Pepe <lamune at doki-doki.net>
> > > > To: CoCoList for Color Computer Enthusiasts
> <coco at maltedmedia.com>
> > > > Sent: Fri, January 1, 2010 7:39:58 PM
> > > > Subject: Re: [Coco] Weird CoCo3 problem...
> > > >
> > > > That's pretty strange. If you have a logic probe you can do some
> > more
> > > > investigation. The LS138 chip may be faulty.
> > > >
> > > > > -----Original Message-----
> > > > > From: coco-bounces at maltedmedia.com [mailto:coco-
> > > > > bounces at maltedmedia.com] Ong happens accept an I/O error - not
> > > light,
> > > > no
> > > > > disk activity, nothing...
> > > > >
> > > > >  Behalf Of Brian Blake
> > > > > Sent: Friday, January 01, 2010 3:24 PM
> > > > > To: CoCoList for Color Computer Enthusiasts
> > > > > Subject: Re: [Coco] Weird CoCo3 problem...
> > > > >
> > > > > Tried the POKE and no drive activity light came on. Anytime I
> > > > > try
> > > to
> > > > > access the disk, nothin
> > > > >
> > > > > ________________________________
> > > > > From: Mike Pepe <lamune at doki-doki.net>
> > > > > To: CoCoList for Color Computer Enthusiasts
> > <coco at maltedmedia.com>
> > > > > Sent: Fri, January 1, 2010 6:08:28 PM
> > > > > Subject: Re: [Coco] Weird CoCo3 problem...
> > > > >
> > > > > I suspect the 6809 as well. But if you do a poke &HFF40,1 the
> > drive
> > > 1
> > > > > activity light should go on. If not something else may be wrong.
> > > > >
> > > > > > -----Original Message-----
> > > > > > From: coco-bounces at maltedmedia.com [mailto:coco-
> > > > > > bounces at maltedmedia.com] On Behalf Of Brian Blake
> > > > > > Sent: Friday, January 01, 2010 2:36 PM
> > > > > > To: CoCoList for Color Computer Enthusiasts
> > > > > > Subject: Re: [Coco] Weird CoCo3 problem...
> > > > > >
> > > > > > Hi Arthur,
> > > > > >
> > > > > > Unfortunately, it's not socketed. Tho, I have about 9 6309's
> > and
> > > > > plenty
> > > > > > of sockets... hmmmm.... maybe tomorrow....
> > > > > >
> > > > > >
> > > > > >
> > > > > > ________________________________
> > > > > > From: Arthur Flexser <flexser at fiu.edu>
> > > > > > To: CoCoList for Color Computer Enthusiasts
> > > <coco at maltedmedia.com>
> > > > > > Sent: Fri, January 1, 2010 3:56:15 PM
> > > > > > Subject: Re: [Coco] Weird CoCo3 problem...
> > > > > >
> > > > > > I vaguely recall something like this happening to me years ago
> > > that
> > > > > was
> > > > > > fixed by replacing the 6809.  If this machine and one of your
> > > > others
> > > > > > has had
> > > > > > the 6809 socketed, it would be easy enough to swap in a 6809
> > from
> > > > one
> > > > > > of the
> > > > > > other machines and see if the problem goes away.
> > > > > >
> > > > > > Art
> > > > > >
> > > > > > On 1/1/10, Brian Blake <random_rodder at yahoo.com> wrote:
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > All of these new developments on the CoCo front finally lit
> > the
> > > > > fire
> > > > > > under
> > > > > > > my arse to set up real hardware again. Besides my repack
> > > project,
> > > > I
> > > > > > have 3
> > > > > > > other CoCo3's, two with 512k upgrades (one C9 and one PBJ)
> > and
> > > > one
> > > > > > 128k. The
> > > > > > > one with the C9 upgrade works fine - can load and play
> > > > Sockmaster's
> > > > > > Donkey
> > > > > > > Kong.
> > > > > > >
> > > > > > > The one with the PBJ upgrade, not so... At boot, it comes up
> > as
> > > > it
> > > > > > should
> > > > > > > with the proper display. However, any floppy commands are
> > > > > > > met
> > > > with
> > > > > no
> > > > > > > response from the floppy drive (with an FD-502 controller)
> > > > > > > at
> > > > all.
> > > > > > Almost
> > > > > > > like the drive is off. The drive responds as it should in
> > > > > > > the
> > > > other
> > > > > > two
> > > > > > > machines. Upon removing the top case and k/b, I saw two
> > wires,
> > > > each
> > > > > > had been
> > > > > > > soldered to opposite sides of R23. Now, under the keyboard,
> > is
> > > > > > another wire
> > > > > > > with alligator clips on each end, and the clips are holding
> > on
> > > to
> > > > > the
> > > > > > bare
> > > > > > > end of the wires soldered to R23, effectively bypassing the
> > > > > resistor.
> > > > > > I'm
> > > > > > > looking for the PBJ instructions, pretty sure I have them,
> > > > > > > to
> > > > find
> > > > > > out if
> > > > > > > this is called for. I can also see where C65 & C66 have been
> > > cut
> > > > > and
> > > > > > > re-soldered. I have reseated the GIME and the PBJ memory
> > chips,
> > > > and
> > > > > > cleaned
> > > > > > > the 40 pin connector.
> > > > > > >
> > > > > > > Any other suggestions? My 100MHz o'scope bit the dust so I
> > > don't
> > > > > have
> > > > > > that
> > > > > > > tool any more (anybody have a CRT for a Leader 3 channel
> > 100MHz
> > > > > > scope??)
> > > > > > >
> > > > > > >
> > > > > > > Thanks,
> > > > > > >
> > > > > > > Brian
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > >
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