adam1977 Posted November 4, 2019 Share Posted November 4, 2019 I'm trying to fix my ColecoVision, i've already sorted a power supply but now there's a problem where the screen looks jittery, it looks as though everything is just moving up and down very slightly I've made a short video, but it doesn't look half as bad when viewed online? maybe that's a clue as to what's wrong with it? Any help will be greatly appreciated Quote Link to comment Share on other sites More sharing options...
Charlie_ Posted November 7, 2019 Share Posted November 7, 2019 Mine does this too. The picture gets better and more stable after the system has been on a few minutes. I guess it needs to warm up. Like my old Dodge? Mine had noise in the audio too, believe it or not removing the lid on the rf modulator fixed that. 1 Quote Link to comment Share on other sites More sharing options...
adam1977 Posted November 7, 2019 Author Share Posted November 7, 2019 Thanks for the reply, i'll leave it powered on for a while then and see if that helps Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted November 7, 2019 Share Posted November 7, 2019 6 hours ago, Charlie_ said: Mine does this too. The picture gets better and more stable after the system has been on a few minutes. I guess it needs to warm up. Like my old Dodge? Mine had noise in the audio too, believe it or not removing the lid on the rf modulator fixed that. Probably needs to adjust the audio tuner. Removing the lid changed the frequency of the audio modulator, apparently for the better. 1 Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted November 7, 2019 Share Posted November 7, 2019 Is your CV AV modded at all? Not that it matters, but the jittering you are talking about...based on your video, I'm wondering if your TV is doing this trying to figure out the interlaced signal coming from the CV? 1 Quote Link to comment Share on other sites More sharing options...
adam1977 Posted November 7, 2019 Author Share Posted November 7, 2019 1 hour ago, -^CrossBow^- said: Is your CV AV modded at all? Not that it matters, but the jittering you are talking about...based on your video, I'm wondering if your TV is doing this trying to figure out the interlaced signal coming from the CV? It's not AV modded, just the standard RF cable output, but I have thought about modding it to get rid of this problem. 2 hours ago, ChildOfCv said: Probably needs to adjust the audio tuner. Removing the lid changed the frequency of the audio modulator, apparently for the better. I'll have a look at that, any idea which pots to adjust? Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted November 7, 2019 Share Posted November 7, 2019 It is possible that getting it AV modded could correct the issue. I know that the entire reason I AV modded my Intellivision was because it was doing the jumping bean dance through RF on my flat panel in the game room. Adding composite to it took care of the issue. In fact, every single Intelly that I've hooked up via RF to that TV screen jumps the entire time and really bugs me to no end. Having said that, I have two CVs. One composite AV modded and the other is nearly stock. Neither one caused any jitteriness like this. The one I AV modded I did so because the RF on it was horrible no matter how much I adjusted it. The other one actually has a really nice RF picture from it and I leave it as is for now. Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted November 8, 2019 Share Posted November 8, 2019 1 hour ago, adam1977 said: It's not AV modded, just the standard RF cable output, but I have thought about modding it to get rid of this problem. I'll have a look at that, any idea which pots to adjust? The one in the corner of the RF box is audio, and the one in the middle is the main channel adjust. If your picture looks great, then the main channel output is probably okay. 1 Quote Link to comment Share on other sites More sharing options...
adam1977 Posted November 9, 2019 Author Share Posted November 9, 2019 I've come across this Ben Heck AV mod, does anyone know if it would be ok for my PAL ColecoVision? Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted November 10, 2019 Share Posted November 10, 2019 17 hours ago, adam1977 said: I've come across this Ben Heck AV mod, does anyone know if it would be ok for my PAL ColecoVision? The transistor is said to get hot, and it also places a load on the video circuit that makes it less than ideal. I think there is a better solution out there that's based on an op-amp. Yeah, here it is. https://store.retrofixes.com/products/colecovision-composite-upgrade-kit 1 Quote Link to comment Share on other sites More sharing options...
adam1977 Posted November 10, 2019 Author Share Posted November 10, 2019 Many thanks for the link, shame it's NTSC only though However i've come across this on eBay, happy days Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted November 10, 2019 Share Posted November 10, 2019 13 hours ago, adam1977 said: Many thanks for the link, shame it's NTSC only though However i've come across this on eBay, happy days I think I'd go for this one instead: https://www.ebay.co.uk/itm/ColecoVision-A-V-Composite-Video-Mod-Kit-NTSC-PAL-LM318/312816022264?_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D2%26asc%3D40733%26meid%3Dcdc4f9fc7235426381b9be3d51a1613d%26pid%3D100623%26rk%3D2%26rkt%3D6%26sd%3D182205220905%26itm%3D312816022264%26pmt%3D0%26noa%3D1%26pg%3D2047675&_trksid=p2047675.c100623.m-1 The only difference between NTSC and PAL is color subcarrier frequency and its phase shift between lines. But none of that matters at final amplification, so you really can use the same circuit either way. 1 Quote Link to comment Share on other sites More sharing options...
adam1977 Posted November 11, 2019 Author Share Posted November 11, 2019 Thanks a lot for the link, i'll contact them and see if they'll post to England I did try and buy the kit from the seller in Turkey, but each time I do my payment gets cancelled... i've contacted him but he hasn't responded. Thanks again. Quote Link to comment Share on other sites More sharing options...
adam1977 Posted November 13, 2019 Author Share Posted November 13, 2019 Well i've ordered the one that ChildOfCV recommended, just have to wait for it to arrive now, many thanks! Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted November 14, 2019 Share Posted November 14, 2019 On 11/11/2019 at 2:03 AM, adam1977 said: Thanks a lot for the link, i'll contact them and see if they'll post to England I did try and buy the kit from the seller in Turkey, but each time I do my payment gets cancelled... i've contacted him but he hasn't responded. Thanks again. I haven't purchased anything from the guy in Turkey from his website in sometime. Last time I tried, PayPal wouldn't go through giving me some error about my account not being authorized for transaction in that country? I did get a reply from the guy where he told me that PayPal had shut down shop in the county and so no PayPal would work through his website store. But... going through his ebay store would and that is what I've been doing. My only problem with this of course, is that his items in his ebay store cost more this way. So not too surprised your payment was cancelled. 1 Quote Link to comment Share on other sites More sharing options...
Charlie_ Posted December 2, 2019 Share Posted December 2, 2019 I purchased and installed the retrofixes A/V mod. It works really well. No more jitters. Very cool too, that the VCS adapter looks great using it. Quote Link to comment Share on other sites More sharing options...
adam1977 Posted December 3, 2019 Author Share Posted December 3, 2019 I bought the one from NY, still haven't had time to install it though Quote Link to comment Share on other sites More sharing options...
adam1977 Posted December 30, 2019 Author Share Posted December 30, 2019 On 11/10/2019 at 10:55 PM, ChildOfCv said: I think I'd go for this one instead: https://www.ebay.co.uk/itm/ColecoVision-A-V-Composite-Video-Mod-Kit-NTSC-PAL-LM318/312816022264?_trkparms=aid%3D1110001%26algo%3DSPLICE.SIM%26ao%3D2%26asc%3D40733%26meid%3Dcdc4f9fc7235426381b9be3d51a1613d%26pid%3D100623%26rk%3D2%26rkt%3D6%26sd%3D182205220905%26itm%3D312816022264%26pmt%3D0%26noa%3D1%26pg%3D2047675&_trksid=p2047675.c100623.m-1 The only difference between NTSC and PAL is color subcarrier frequency and its phase shift between lines. But none of that matters at final amplification, so you really can use the same circuit either way. Have you got a wiring diagram for this PCB please? I'm about to install it and my PAL board is different to the NTSC one. I've looked at this YouTube vid but the mod board he's using is different to mine Help! Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted December 31, 2019 Share Posted December 31, 2019 Well, I'd love to tear apart a PAL version if I could find one over here. Unfortunately not yet. I just browsed eBay UK and found that they seem pretty proud of them. £75 starting bid with reserve... for one that's not working. Looks like the PCB has +12V, GND, IN and OUT labeled. IN goes to the transistor near the video modulator chip on the main board and OUT goes to the video jack. As far as the audio goes, it seems that with this board you're expected to just hook the audio tap point (the red wire) direct to the audio jack. 1 Quote Link to comment Share on other sites More sharing options...
adam1977 Posted December 31, 2019 Author Share Posted December 31, 2019 Many thanks! I take it then with this board I don't need to remove the resistor etc? Prices are pretty steep over here for CV's, it's probably down to it's rarity Quote Link to comment Share on other sites More sharing options...
ChildOfCv Posted December 31, 2019 Share Posted December 31, 2019 Unfortunately, I don't know what still needs to be modded for that case. Does the resistor do audio or video stuff? Or, maybe it's what mixes the modulated audio into the composite signal just before channel modulation. My advice is to go ahead and do the entire mod, but make sure whatever you do is reversible so that things can be added back if you don't get a fully working system. But it's possible that even with the direct audio connection, you still need to do the whole mod. In fact, for all I know, maybe the version of board that takes audio just passes it through to the audio output anyway, and this version skips the middle man. 1 Quote Link to comment Share on other sites More sharing options...
adam1977 Posted December 31, 2019 Author Share Posted December 31, 2019 I'm not sure either, but I appreciate you taking the time to try and help me with this buddy I'll persevere with it and do some more research. Happy New Year! ? Quote Link to comment Share on other sites More sharing options...
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