Differences
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— | av:cbs_coleco [2019/08/27 20:45] (current) – created - external edit 127.0.0.1 |
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| ====== CBS Colecovision Audio/Video Modification ====== |
| {{av:colecoguts.jpg}} \\ |
| This information is relevant to the CBS Colecovision (PAL). |
| ===== Composite Video ===== |
| {{av:colecoav_2.png}} \\ This is a circuit diagram of the latter part of the Coleco's video circuit. Components in red are additional parts required to drive a standard TV/Monitor. The Video wire (blue) must be disconnected (thus disabling the RF out) in order for the transistor amplifier to fuction. I reccomend lifting the leg of Q24 off the board and connecting the 3k3 resistor between the lifted leg and the nearest +5v point as this part if the circuit is susceptible stray capacitance. R140 should be reduced to about 3300 ohms. This actually forms a low pass filter with Q24 (miller effect). You may want to adjust this value to your tase (don't use a pot!). Higher value = softer edges and less dot crawl (chroma interference), lower value = sharper edges. The resaulting video signal is of very good quality with only minimal dot crawl. |
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| {{av:colecoav_audio.png}} \\ I didn't bother to trace out the audio circuit. Just intercept the wire going to the modulator board. Use a resistor divider to attenuate the signal. |