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

[Torsten Dittel]

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