+-^CrossBow^- Posted August 3, 2014 Share Posted August 3, 2014 This might very well be my first post in the Colecovision section! Anyway, I just did the Benheck composite mod on my CV today and am quite pleased with the results on my flatpanel! The only issue I have with this mod, is that the 1k trimmer pot that I have seems to really only be all the way open or pretty much closed off completely..hmm. My problem with that is I noticed the 4401 gets insanely hot! I checked the voltages and that is likely due to the nearly 12volts it is receiving on the emitter line. I tried to dial down the trimmer and actually get a picture without the trimmer, but it is very dark and really needs the amp circuit. Mine seems to need at least 7 - 8 volts steady for the amp circuit to produce a good picture. However, the best I can get is about 9.5 volts on my adjustments...ugh. Anyway it is a very easy AV mod to perform and with so much space in the CV it is even easier than most! Here is a before of Fathom's title screen.... And here it is after on the composite out......sorry about the flash on this one. Here is a shot of pcb I out the circuit on and where everything is attached. So yeah I'm happy with how it turned out and very glad to be rid of the noise on the screen. When I first got this CV back around 2000 or so, it had a horrible RF picture and no sound. I had to adjust the RF modulator to get the sound and video cleaned up and the top pic is still the best it can get today. The mod I did still keeps the RF video and audio intact and is also compatible with the expansion module 1 should I ever want to use one. 1 Quote Link to comment Share on other sites More sharing options...
NIAD Posted August 3, 2014 Share Posted August 3, 2014 Congrats and welcome to the CV&ADAM Forum. If by chance you mod any other CV systems in the future, check out Yurkie's A/V Mod board that he sells here and on eBay. Quote Link to comment Share on other sites More sharing options...
iscout62 Posted August 3, 2014 Share Posted August 3, 2014 youll probably want to move that off the vram, those 4116 chips get hot.. Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 3, 2014 Author Share Posted August 3, 2014 Hopefully the double sided foam pad I used to hold that pcb in place will insulate it from the heat of the vram chips. Quote Link to comment Share on other sites More sharing options...
thecrypticodor Posted August 3, 2014 Share Posted August 3, 2014 Maybe you can use a 7808 voltage regulator in place of the trimmer to drop the voltage down to 8v. Or you could possibly make a shunt circuit with something like a 1N4737 (7.5V) zener diode. Also that transistor mod is really supposed to have a 47uf capacitor and a 75 ohm resistor for impedance voltage matching. Quote Link to comment Share on other sites More sharing options...
chart45 Posted August 3, 2014 Share Posted August 3, 2014 get the f18a video board the color and definition is perfect Quote Link to comment Share on other sites More sharing options...
NIAD Posted August 3, 2014 Share Posted August 3, 2014 get the f18a video board the color and definition is perfectA bit more expensive option, but indeed another GREAT option to consider for modding the CV... or in my case one of my ADAMs. Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 3, 2014 Author Share Posted August 3, 2014 (edited) Hmm.. I do have a 47uf cap laying around. don't have 75ohm resistors but I got a 68 and some 10s laying around. Adding those to the PCB I think I can do without having to redo it or just add it to the composite inline out. Thanks for the tip! Again, I was just using Benheck's circuit and it has been replicated by others as those are usually what come up first when googling CV composite mods. Also I didn't use the ground point marked in most of the mods like you have specified on the RF circuit. I just used the solder ground glob for the RF shielding on the middle right hand side to attach to. I also forgot to mention that the reason the image is now stretched is because of the composite & s-video upscaler I use. It is a cheap one but works quite well. However, it outputs everything through HDMI and my TV doesn't allow me to switch to 4:3 aspect on the HDMI inputs. Likely because by the time HDMI came out, all TVs were widescreen supported anyway. So yeah, I'm stuck in 16:9 when using any of the digital signals on this particular TV. Still the TV was cheap at the time and I've gotten quite used to the image after several years. Edited August 3, 2014 by -^Cro§Bow^- Quote Link to comment Share on other sites More sharing options...
Greg2600 Posted August 3, 2014 Share Posted August 3, 2014 Congrats and welcome to the CV&ADAM Forum. If by chance you mod any other CV systems in the future, check out Yurkie's A/V Mod board that he sells here and on eBay. I would second this! I had Yurkie do a CV, 2600, and 7800 for me with that 3.5mm jack. Also had a 5200 composite modded, so I can use the same wire for all 4! If only there was an Intellivision mod.... Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted August 3, 2014 Author Share Posted August 3, 2014 Maybe you can use a 7808 voltage regulator in place of the trimmer to drop the voltage down to 8v. Or you could possibly make a shunt circuit with something like a 1N4737 (7.5V) zener diode. Also that transistor mod is really supposed to have a 47uf capacitor and a 75 ohm resistor for impedance voltage matching. Colecovision av mod.png Crypticodor! Adding the cap and resistors did the trick! The trimmer now dials correctly as it should and I have a nice stable picture at 8 volts. Anything less and the colors start to wash out. Best of all the 4401 isn't getting hot anymore and now it shouldn't nuke itself with extended hours of operation. So thanks again! Quote Link to comment Share on other sites More sharing options...
chart45 Posted August 4, 2014 Share Posted August 4, 2014 I would second this! I had Yurkie do a CV, 2600, and 7800 for me with that 3.5mm jack. Also had a 5200 composite modded, so I can use the same wire for all 4! If only there was an Intellivision mod.... someone know where i can get this 3.5mm av chassis socket in canada or a place who ship usps from us cause i dont want a pay 30$ shipping on a 6$ order Quote Link to comment Share on other sites More sharing options...
iscout62 Posted August 5, 2014 Share Posted August 5, 2014 (edited) Check here..http://www.digikey.com/product-search/en?FV=fff40016%2Cfff80517%2C8fc0004&k=3.5mm+jack&mnonly=0&newproducts=0&ColumnSort=0&page=2&stock=0&pbfree=0&rohs=0&quantity=&ptm=0&fid=0&pageSize=25 and on ebay http://www.ebay.com/sch/i.html?_odkw=3.5mm+barrel&_osacat=0&_from=R40|R40|R40|R40&_from=R40&_trksid=p2045573.m570.l1311.R4.TR4.TRC1.A0.H1.X3.5mm+pcb+&_nkw=3.5mm+female+pcb&_sacat=0 Edited August 5, 2014 by iscout62 Quote Link to comment Share on other sites More sharing options...
Greg2600 Posted August 5, 2014 Share Posted August 5, 2014 The jack is often called a TRRS mounted 3.5mm. This is the one I bought. http://www.showmecables.com/product/35mm-trrs-jack-panel-mount-connector-metal.aspx Similar to this one. http://www.digikey.com/product-detail/en/SJ-43502PM/CP-43502PM-ND/382942 These are great because you can secure them with the bushing nut, and do not need any glue. You can also get stereo by soldering an arc between the audio slot you feed from the system, and the open one. Just be sure to identify each solder point correctly with the AV 3.5mm cable you're going to use. Quote Link to comment Share on other sites More sharing options...
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