Difference between revisions of "Composite color video out"

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== Composite color video out ==  
 
== Composite color video out ==  
  
As known, our computer has "only" professional outputs for the monitors: an analogue RGB for the colour monitors and a monochrome composite signal for the B&W ones.
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The Enterprise computer series (64/128) has three possible "monitor" outputs available. An analogue RGB for colour monitors, a monochrome composite signal for Black and White monitors and finally an RF output via the built in UHF modulator suitable for use with many televisions via the aerial socket.
Other alternative is using the built-in UHF modulator. But this has drawbacks: as long as you use the television for displaying the UHF signal, the resolution gets notably worse and worse and you are constrained to fine tune the TV, as the RF modulator built in the computer isn't famous for its stability.
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The UHF modulator built into the Enterprise has its drawbacks, the longer you use the television for displaying the UHF signal the more the signal deteriorates until you are forced to fine tune the TV, this is due to the built in RF modulator being "famous" for its stability (or lack thereof !!).
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Nowadays there are many TVs containing (baseband) video input and there are many monitors which are able to receive video signal only. (Not to mention the VCRs.) The emitter follower in question makes it possible to connect the Enterprise to them. It can be built into the machine and the colour PAL video signal can be led out of the computer through an empty connector pin.
 
Nowadays there are many TVs containing (baseband) video input and there are many monitors which are able to receive video signal only. (Not to mention the VCRs.) The emitter follower in question makes it possible to connect the Enterprise to them. It can be built into the machine and the colour PAL video signal can be led out of the computer through an empty connector pin.
 
The signal containing the colour information can be taken from the base of the transistor represented on the original circuit diagram "TR8 (2N3904)". The composite video signal present here is generated by the integrated circuits "U34 (LM1886)" and "U35 (LM1889)". The one-stage transistor amplifier to be built-in can be seen in picture 1.[[Image:Composite-1.gif]]
 
The signal containing the colour information can be taken from the base of the transistor represented on the original circuit diagram "TR8 (2N3904)". The composite video signal present here is generated by the integrated circuits "U34 (LM1886)" and "U35 (LM1889)". The one-stage transistor amplifier to be built-in can be seen in picture 1.[[Image:Composite-1.gif]]
  
Now we are going to review how to build in the emitter (follower?). This work is recommended only for those who are expert in electronic tinkering. Not having the suitable tools (for example to do the accurate soldering) many sources of failure can be built into the machine disassembling and reassembling it. First of all, remove all the plugs from the machine and the BASIC cartridge from the left side of the computer. Screw off the 14 (kereszthornyú?) screws at the bottom. The keyboard can be removed by carefully tipping it over (?). Now the transparent folder of the funtion keys' label can be removed. Slip the upper housing (burkolat?) progressively (fokozatosan?), slowly up in more places (?). Lift it down carefully because the foil cable can break. Remove the foil from the two connectors on the motherboard. <!-- A fémdobozzal árnyékolt RF modulátorhoz közel találjuk meg a mellékelt 2. ábrán és a panelon a pozíciószámmal jelölt alkatrészeket.
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Now we are going to review how to build in the emitter follower. This work is recommended only for those who are expert in electronic tinkering. Not having the suitable tools (for example to do the accurate soldering) many sources of failure can be built into the machine disassembling and reassembling it. First of all, remove all the plugs from the machine and the BASIC cartridge from the left side of the computer. Unscrew the 14 (kereszthornyú?) screws at the bottom. The keyboard can be removed by carefully tipping it over (?). Now the transparent folder of the funtion keys' label can be removed. Slip upwards the upper housing/casing (burkolat?) progressively (fokozatosan?), slowly, in more places (?). Lift it down carefully because the foil cable can break. Remove the foil from the two connectors on the motherboard. <!-- A fémdobozzal árnyékolt RF modulátorhoz közel találjuk meg a mellékelt 2. ábrán és a panelon a pozíciószámmal jelölt alkatrészeket.
 
[[Image:Composite-2.gif]]
 
[[Image:Composite-2.gif]]
 
A BC182 tranzisztor kollektorát a C36-os (100nF) kondenzátor "felső" lábához (+12V), a bázist (középső láb) a TR8 bázisára menő fóliaponthoz forrasztjuk. Az emitterre csatlakozik az 510 ohmos és a 75 ohmos ellenállás. Mindegyik ellenállás kisméretű legyen, a kivezetésekre szigetelést húzva akadályozzuk meg a zárlatot! Az 510 ohmos ellenállást a C211-es elektrolit kondenzátor negatív lábához (földpont) visszük. A 75 ohmot sorbakötjük a 47 mikrofarados elektrolit kondenzátorral, annak negatív pólusát vezetjük vékony vezetékkel a monitorcsatlakozó B1-es pontjára (ez a magnócsatlakozók felöli felső aranyozott csík). A földpont a monitorcsatlakozón az A2 és a B2 érintkező, azaz alul és felül a második pont. Az összeszerelést a fóliacsatlakozók visszadugásával kezdjük. Két kézzel nagyon óvatosan, a megtörést elkerülve billegtetjük helyre a vékony fóliasávokat. Kockázatos művelet! Igazítsuk helyére a bekapcsolásjelző LED fényvezető búráját is! Finoman visszatesszük a felső burkolatot, majd a címkék műanyag tartóját. A billentyűzet következik, ez rögzíti az előbbi címketartót, majd jöhet a 14 csavar és a Basic ROM. Ha a monitorcsatlakozót is bekötöttük, bármilyen színes TV vagy monitor videobemenetére csatlakozva megvizsgálhatjuk a képminőséget. Akár videomagnóra is rögzíthetjük számítógépünk színes ábráit.
 
A BC182 tranzisztor kollektorát a C36-os (100nF) kondenzátor "felső" lábához (+12V), a bázist (középső láb) a TR8 bázisára menő fóliaponthoz forrasztjuk. Az emitterre csatlakozik az 510 ohmos és a 75 ohmos ellenállás. Mindegyik ellenállás kisméretű legyen, a kivezetésekre szigetelést húzva akadályozzuk meg a zárlatot! Az 510 ohmos ellenállást a C211-es elektrolit kondenzátor negatív lábához (földpont) visszük. A 75 ohmot sorbakötjük a 47 mikrofarados elektrolit kondenzátorral, annak negatív pólusát vezetjük vékony vezetékkel a monitorcsatlakozó B1-es pontjára (ez a magnócsatlakozók felöli felső aranyozott csík). A földpont a monitorcsatlakozón az A2 és a B2 érintkező, azaz alul és felül a második pont. Az összeszerelést a fóliacsatlakozók visszadugásával kezdjük. Két kézzel nagyon óvatosan, a megtörést elkerülve billegtetjük helyre a vékony fóliasávokat. Kockázatos művelet! Igazítsuk helyére a bekapcsolásjelző LED fényvezető búráját is! Finoman visszatesszük a felső burkolatot, majd a címkék műanyag tartóját. A billentyűzet következik, ez rögzíti az előbbi címketartót, majd jöhet a 14 csavar és a Basic ROM. Ha a monitorcsatlakozót is bekötöttük, bármilyen színes TV vagy monitor videobemenetére csatlakozva megvizsgálhatjuk a képminőséget. Akár videomagnóra is rögzíthetjük számítógépünk színes ábráit.

Latest revision as of 14:24, 29 August 2007

Composite color video out

The Enterprise computer series (64/128) has three possible "monitor" outputs available. An analogue RGB for colour monitors, a monochrome composite signal for Black and White monitors and finally an RF output via the built in UHF modulator suitable for use with many televisions via the aerial socket.

The UHF modulator built into the Enterprise has its drawbacks, the longer you use the television for displaying the UHF signal the more the signal deteriorates until you are forced to fine tune the TV, this is due to the built in RF modulator being "famous" for its stability (or lack thereof !!).

Nowadays there are many TVs containing (baseband) video input and there are many monitors which are able to receive video signal only. (Not to mention the VCRs.) The emitter follower in question makes it possible to connect the Enterprise to them. It can be built into the machine and the colour PAL video signal can be led out of the computer through an empty connector pin. The signal containing the colour information can be taken from the base of the transistor represented on the original circuit diagram "TR8 (2N3904)". The composite video signal present here is generated by the integrated circuits "U34 (LM1886)" and "U35 (LM1889)". The one-stage transistor amplifier to be built-in can be seen in picture 1.Composite-1.gif

Now we are going to review how to build in the emitter follower. This work is recommended only for those who are expert in electronic tinkering. Not having the suitable tools (for example to do the accurate soldering) many sources of failure can be built into the machine disassembling and reassembling it. First of all, remove all the plugs from the machine and the BASIC cartridge from the left side of the computer. Unscrew the 14 (kereszthornyú?) screws at the bottom. The keyboard can be removed by carefully tipping it over (?). Now the transparent folder of the funtion keys' label can be removed. Slip upwards the upper housing/casing (burkolat?) progressively (fokozatosan?), slowly, in more places (?). Lift it down carefully because the foil cable can break. Remove the foil from the two connectors on the motherboard.