[Coco] Jammaboard CV-04 for Coco3

[Gene Heskett]

On Friday 13 December 2013 12:45:57 Steven Hirsch did opine:

> On Fri, 13 Dec 2013, Luis Antoniosi (CoCoDemus) wrote:
> > Steven you complained about the s-video on your Samsung but is it well
> > grounded ? Did you plug the sound RCA cable too? I saw some stupid TVs
> > to take the ground from audio plug only and maybe it's getting a
> > ground loop. Worth trying even if you have another s-video cable or
> > other s-video capable device to test.
> 
> Good thought.  It acts exactly like one of the video signals is creating
> a beat frequency against the 60Hz. line.  But, unfortunately tying
> another ground did not help.
> 
> I spent yesterday morning driving around to every local recycler and
> store who might have used LCD monitors.  Looked at perhaps 30 units -
> not one of which had an S-Video input.
> 
> My friend had a little 13" Sharp TV/Monitor with VGA, composite and
> S-Video, but it exhibits the same problem as the Samsung 730MW.  With
> his vast knowledge of things video, I wonder if Gene Heskett can
> decipher what's happening with these units?

From the description, I'll have to plead no clue.  The only possibility I 
can think of might be an out of tolerance subcarrier frequency being 
generated by your svga source.  That would leave you with a loss of color 
subcarrier sync and very distracting color bands rolling thru the pix.

We, when broadcastng NTSC color, were constrained to a tolerance of 10 hz 
either way from 3579545.4545454545hz, which itself was a physically imposed 
limit because of the Rhubidium frequency clocks used as frequency standards 
at the major networks, something a bit pricey for us common broadcasters.

So we generally used a temperature compensated crystal based oscillator 
that we would occasionally tweak by zero beating against the network input 
signal.  But when the distribution switched from cross country microwave 
links, whose path lengths from mountain top to mountain top were quite 
stable, to satellite links, the station keeping movements of the satellite, 
which for minimum fuel use actually described a figure 8 due to the pull of 
the moon in a days time, then we had to get a little schmardter about that.

Since we generally weren't privy to the birds exact position and relative 
speeds, we had to make use of the vectorcope, used as a comparator by 
looking at the network signal while synched to our house signal, noting 
both the the speed of the patterns rotation but which direction they 
rotated & the best we could do was to let it spin a bit, and check again at 
6 hour intervals, trying to get the spins at max spin rate we found, to 
match in the other direction 12 hours later.

Some enterprising engineer with too much time on his hands & trying to look 
busy probably designed a zero error recorder, logging the time it occurred, 
and we would be quite close if the zero error condition occurred at 
nominally 12 hour intervals, but I never considered undertaking to do that 
myself, and if such a device was being made, I never saw it in the trade 
magazines.

Your error could then be inferred from how lopsided timewise that the 
zero's occurred.  However a 10 rps spin would have been quite rapid, the 
FCC tolerance, was rarely seen.  That would have told us something is 
happening to the bird.  ISTR seeing something similar in the hour or so 
before it was announced that one of the early telstars had failed, nearly 
out of fuel.  It used its last to get to induce a drift to a semi stable 
spot over the pacific where it wouldn't run into anything, and was used, 
with ground stations tracking its motions for another 10 years or so.  I 
was glad to see it go as it was one of the more mouse powered birds, since 
replaced by birds that can do 20 or more watts.

That figure 8 the satellite moved in per 24 hours, was, at an average 
distance of 22,300 miles out, as much as 100 miles in and out and 50+ miles 
sideways.  Lots and lots of wavelengths of a 3.579545mhz signal in those 
in/out motions IOW.

All of which hasn't a thing to do with the OP's problem, I'm just rambling.

> My Samsung 214T provides a perfect display, but I really don't want to
> remove it from my audio editing work station.  eBay, here I come.
> 
> Steve

That may be your best bet.  Occasionally one might find a trimmer to adjust 
that frequency in the monitor, but to identify it if it existed, would 
probably take the factory service manual for that monitor, and its been my 
experience with the Chinese stuff that no such manual exists.  Sony & 
Panasonic, yes, but for them its a cash cow, with asking prices usually 
starting with 3 digits left on the decimal point.  ebay would be cheaper if 
you hit a lick.

Cheers, Gene
-- 
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