[Coco] Coco 3 with problems, can anyone help me troubleshoot?

Sat Feb 11 21:58:27 EST 2012

On Saturday, February 11, 2012 08:58:10 PM Mike Rowen did opine:

> Have you checked your cassette cable?
> 
That is another possibility Mike, but if he can hear the tape in the 
speakers hooked _to_ the coco, then I'd like to think the cable is good.  
So the next question I'd have is, was the coco3 slowed to coco2 speed when 
that tape was written, and its also slowed to coco2 speed before the tape 
read is attempted?

Frankly, the noise performances of the CCR-81 and look-a-likes have always 
disappointed me, a lot.  The DC magnet erase and bias setups on those put 
so much noise and distortion on the tape that I have applied the same 
theory to those that we used back in Model T Ford days, which was said to 
have Christian Science oiling because you had to be a CS to believe the 
cylinder walls got enough oil.  They never did.

So while my metal tape capable Sony dual deck machine didn't have an 
interface that allowed its motors to be controlled by the coco, it was no 
problem to start the deck in record mode, then hit the return key to start 
the coco's output, stopping the deck when the prompt came back.  I have yet 
to fail to read back such a tape even though it was only on one track of a 
stereo deck, even when that tape was played back in a GE copy of that 
CCR-81.  I even mailed out a few copies of some stuff to others who 
reported they were flawless.

So, that brings us back to his problem.

Please give us a little better description of what that buzzing really 
sounds like.  They should be rather raspy, with noticeable output from the 
tweeters if you have that fancy a speaker set.  If it sounds like it has 
been through a low pass filter, with no more highs to drive the tweeters 
than you would get thru a phone circuit, I'd have to guess that one, either 
the head was dirty and the tape is not making good contact, or two the head 
is worn out, or the felt pressure pads in the cassette are missing. 
Obviously a fresh cassette and a fresh recording would tell that tale.

The head being worn needs a quite strong magnifying glass to see if you can 
actually see the pole piece gaps where they come together, usually much 
much less than 0.001" and invisible even to a 100 power glass/microscope, 
so basically if you can see the gap, running vertically on the face of the 
head, its gone.  This will also be visible it the supposedly cylindrical, 
well polished profile of a good head.  If it looks like its worn unevenly, 
its safe to bet its worn out.  Even good heads are like diamond phono 
needles, and gone in 500 to 1000 hours of use, unless it says Ampex 600 on 
the deck, they were much thicker and could hold specs for 30k hours.

This is not to belittle Mark in any way.  Its even possible that a coat of 
something atmospheric born is on the head after all these years, no fault 
of Mark's at all, and that a decent cleaning and letting a fresh cassette 
play through it full length to restore the polish might be in order.  Since 
they are made of an alloy called mu-metal, its conceivable that they could 
also "rust" like iron would but I've no clue what color it might be if that 
is the case.

Wikipedia says this about the alloy:
Mu-metal is a nickel-iron alloy (approximately 77% nickel, 16% iron, 5% 
copper and 2% chromium or molybdenum)[1]

That 16% iron could be an oxidation problem over the 20+ years since these 
CCR decks were made.  On iron, we call that oxidation rust but I'd have to 
think its not anything but surface and an in-determinant color what with 
all the other stuff, like copper which also oxidizes over time.  So will 
the chromium which is why your cars bumpers have a coat of nickle over the 
chrome to keep it nice & bright for a while.

The wiki article does not discuss its oxidation modes or properties.
Another site does allude to it with this statement:

Mumetal is only moderately resistant to moisture and atmospheric corrosion,

And that seems to about the extent of available data since the rest of 
those sites are interested in selling you some of it. ;-)

However, beware of 'cleaning tapes' those things are like 320 grit 
sandpaper, every 10 seconds can take 50 hours off a heads life.

If the full length pass of a new 2 hour tape fixes it, toss that tape, its 
now contaminated and having done its job, needs to hit the trash can.

Hopefully I've hit the rest of the bases here.

> On Feb 11, 2012, at 8:45 PM, haywire666 at aol.com wrote:
> > I removed and thoroughly cleaned the gime chip and socket. no gook or
> > noticable grime to speak of though when I started....
> > 
> > 
> > Interestingly no more garbage screen bootups so cleaning the gime chip
> > and contacts did something, but when I try to CLOAD the same problem
> > happens (S character in upper left hand corner of screen) tape plays
> > and machine locks in that state...
> > 
> > 
> > Motor on/motor off commands work.
> > 
> > 
> > audio on and audio off commands work.
> > 
> > CSAVING appears to work. At least I think so... With audio on, I hear
> > a bunch of buzzing when what I saved is played back...
> > 
> > 
> > Steven
> > 
> > 
> > 
> > -----Original Message-----
> > From: haywire666 <haywire666 at aol.com>
> > To: coco <coco at maltedmedia.com>
> > Sent: Sat, Feb 11, 2012 8:20 pm
> > Subject: Re: [Coco] Coco 3 with problems, can anyone help me
> > troubleshoot?
> > 
> > 
> > 1) I have a ccr radio shack cassette I just got from cloud9.
> > 
> > 
> > 2) When I use audio on commands I can hear stuff from the tape, but
> > its been years since I heard a data tape. Sounds right from what I
> > recall.
> > 
> > 
> > 3) When I cload, the tape indeed starts, I get an S in the upper left
> > corner of the screen. The tape stays on forever. The machine's state
> > never changes, even when I left it for an hour.
> > 
> > 
> > 4) I don't have a prerecorded tape to check. I am just now getting
> > back to cocos (My first computer love) after many years off...
> > 
> > 
> > 5) I don't think its high speed poked, I boot the computer the cursor
> > looks regular speed, when I try it from clean cold boot this happens.
> > 
> > 
> > 6) Someone else suggested pulling and cleaning the contacts of the
> > gime chip. Just got back from radio shack, got an extraction tool...
> > so I'm trying that now.
> > Pulled the chip, both the chip and the sockets contacts look really
> > dingy and dirty... so I hope maybe thats it. I'm going to go work on
> > this now will post results.
> > 
> > Thanks for everyone's help... Hopefully my poor coco3 will be feeling
> > much healthier soon!
> > 
> > Steven
> > 
> > 
> > 
> > -----Original Message-----
> > From: Arthur Flexser <flexser at fiu.edu>
> > To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> > Sent: Sat, Feb 11, 2012 6:54 am
> > Subject: Re: [Coco] Coco 3 with problems, can anyone help me
> > troubleshoot?
> > 
> > 
> > You might narrow down things by using the AUDIO ON command to see if
> > the tape sounds normal when it is saving and when you attempt to load
> > a program.
> > 
> > Also, make sure you aren't in the double speed mode;  the cassette
> > routines must be patched to work properly at that speed.
> > 
> > When you say it "just hangs", I assume you've verified that the tape
> > is advancing properly?  Do the MOTOR ON and MOTOR off commands
> > function?
> > 
> > Art
> > 
> > On Sat, Feb 11, 2012 at 5:12 AM,  <haywire666 at aol.com> wrote:
> >> I have a color computer 3 with some problems. I thought it was a cold
> >> solder
> > 
> > joint or something. Occasionally it would not boot right (I'd get a
> > garbage screen) The real problem however is that once its working, I
> > can save programs with csave to cassette, but when I try cload, I get
> > an S on the upper left corner of the screen and then it just hangs.
> > 
> >> Has anyone seen this before? Can anyone give me some trouble shooting
> >> tips?
> > 
> > Not being able to save programs (just bought a cassette for that
> > purpose) is driving me kind of nuts.
> > 
> >> Steven
> >> 
> >> 
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Cheers, Gene
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