[Coco] WTB: PAL CoCo (1, 2, or 2B) for shipment to USA

[Daniel Campos]

Torsten,

Nice piece of information!! Thanks for sharing!

Regards,
Daniel

2013/2/28 Torsten Dittel <OS-9 at trs-80.cc>

> Jayeson,
>
> I should have several Service Manuals for differnt CoCo1 to CoCo3 PAL
> models
> (access might be not that easy currently because it's all stored in
> boxes). If
> noone else finds these and/or has it already scanned, I might give a try
> to dig
> them out.
>
> Some other things just came to my mind (which is a little bit rusty after
> all
> these years):
>
> I own PAL CoCos (and MC-10s) from different areas and they are all slightly
> different.
>
> AFAIR, there's one group which has been sold in Germany, Belgium & the
> Netherlands (CoCo 1 to 2B). These are following the PAL-G standard and
> have a
> modulated RF video out on UHF (0.3-3.0 GHz) channel 36 (this channel was
> originally kind of reserved for this purpose: computers, video recorders,
> etc. -
>  in times where you only had 3 terestrical analog TV programs and not yet
> SCART
> and/or composite video inputs in  your TV sets). A channel switch was not
> present (the corresponding hole in the CoCo's case was covered by a plate
> reading "Channel 36").
>
> Some key dates for PAL-G:
>
> Vertical scan lines: 625
> Vertical frequency: 50 Hz
> Horizontal frequency: 15.625 kHz
> Video band-width: 5.0 MHz
> Audio carrier: 5.5 MHz
> Color subcarrier frequency: 4.43361875 MHz
> Channel spacing: 8 MHz
> Vision modulation type: AM
> Vision modulation polarity: negative
> Sound modulation: FM
> Vestigial side-band: 0.75 MHz
> Field period: 1/50 s = 20 ms
>
> There's another type sold in United Kingdom (Great Britain [England,
> Scotland,
> Wales] and Northern Ireland), I assume this one follows PAL-I standard
> (difference to PAL G: Video band-width is 5.5 Mhz [instead of 5.0 MHz],
> Vestigial side-band is 1.25 MHz [instead of 0.75 MHz] and the audio
> carrier is
> at 6.0 MHz [instead of 5.5 Mhz]). The latter has the effect, that on a PAL
> G TV
> you can either have the sound correctly tuned or the image. It was rather
> using
> VHF (0.03-0.3 GHz) [instead of UHF], so it had the "Channel 3(?) or 4(?)"
> select switch.
>
> From Australia, I got at least some PAL CoCo3 (the PAL CoCo3 had never been
> sold in Europe, because Tandy/RadioShack closed its stores in the time the
> CoCo3 came out. The CoCo2B [lower-case, 6847-T1 VDG] was never officially
> available in Germany, but I got one with a very low serial number which
> was a
> demonstrator from our local store). Australia has PAL B/G, and AFAIR the
> machines have the VHF "channel 2(?) & 3(?)" switches, so I assume CoCo3s
> are
> PAL-B machines. However, you would rather use the composite video out or
> the
> RGB out with a CoCo 3 and not the RF modulator. Composite video out is
> generated from the RGB out with a piggy-backed satellite board, the GIME's
> NTSC
> composite out is not connected on PAL boards. The PAL CoCo3 has a modified
> PAL
> ROM too (initializing the GIME to 50Hz video timing).
>
> The strangest group of machines (CoCo1 to CoCo2B) come from France. These
> have
> a French AZERTY keyboard layout [instead of QWERTY in both the US and the
> rest
> of Europe - at least in Germany we would have prefered a QWERTZ layout, but
> noone cared :-)]. The modulator has been completely replaced by a VDG to
> RGB
> circuit, which is compatible with the French SECAM-L TVs. For the sake of
> completeness, a SECAM-L RF modulator would have to comply with the
> following (I
> think they were sold as an external device):
>
> Vertical scan lines: 625
> Vertical frequency: 50 Hz
> Horizontal frequency: 15.625 kHz
> Video band-width: 6.0 MHz
> Audio carrier: 6.5 MHz
> Color subcarrier frequency: 4.406250 MHz/ 4.250 MHz
> Channel spacing: 8 MHz
> Vision modulation type: AM
> Vision modulation polarity: positive
> Sound modulation: AM
> Vestigial side-band: 1.25 MHz
> Field period: 1/50 s = 20 ms
>
> The French CoCo PCBs have an additional +12V voltage generator on board,
> which
> is output along with R, G, B, H+V (which is AFAIR actually a composite sync
> signal) on a small Mini-DIN connector. Then you need a special Mini-DIN to
> Péritel (=Euro-SCART) cable, which contains voltage devider to create
> switch
> voltages which set the video sink (the TV) to RGB mode (rest-of-Europe
> SCART
> often runs on composite video mode only).
>
> Hope that is kind of interesting (depite it doesn't solve your problem
> yet).
>
> Best regards,
> Torsten
>
>
>
>
> --
> Coco mailing list
> Coco at maltedmedia.com
> http://five.pairlist.net/mailman/listinfo/coco
>