alortegac Posted November 23, 2016 Share Posted November 23, 2016 Dear expert and knowledgeable members of this forum, I request your for assistance in diagnosis of the illness my colecovision is suffering from. I hope it can be rescued from going into the recycle bin,. The logic of my system seems to working fine but the picture is scrambled. Reading games, etc. However, please see pictures attached as description of the problem, I am getting characters and odd colors..... I will be grateful about any guidance on the root cause of this problem and its potential solutions. I have already cleaned the power button. I do think that is the problem. Also power supply is working fine, tested. Thank you very much in advance for your assistance. Quote Link to comment Share on other sites More sharing options...
cdn2a Posted November 23, 2016 Share Posted November 23, 2016 From the looks of it, I'd say ram failure. https://console5.com/store/colecovision-5v-memory-upgrade-kit.html Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted November 23, 2016 Share Posted November 23, 2016 Fist step in graphical glitches is to clean the power switch. If that doesn't work, then try a different power supply. Last resort upgrade the Video RAM or get F18a upgrade. 1 Quote Link to comment Share on other sites More sharing options...
chart45 Posted November 23, 2016 Share Posted November 23, 2016 look more a power issue than ram you can look at those image in the repair manual to know with ram chip is defective http://www.colecovisionzone.com/photos/coleco/colecovision%20tech8.pdf Quote Link to comment Share on other sites More sharing options...
alortegac Posted November 28, 2016 Author Share Posted November 28, 2016 thank you very much for your advise. 1.- New Ram is on order from Console5./ thanks! 2.- Power switch has been cleaned and multiple power supplies have been tried. thanks! 3.- Chart45. thank you very much for this information. Although I do not have equipment to check frequencies, trouble shooting described will help me. thank you all, keep you posted. Al Quote Link to comment Share on other sites More sharing options...
alortegac Posted November 28, 2016 Author Share Posted November 28, 2016 (edited) Sorry to ask but what is an F18a upgrade? thanks! Edited November 28, 2016 by alortegac Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted November 28, 2016 Share Posted November 28, 2016 It is a replacement video display processor. It is an FPGA board that emulates the stock VDP but adds several features such as extended color palattes and smooth scrolling for games that are programmed to take advantage of it. It also provides a flicker free VGA output since it allows 32 sprites to be drawn at a time instead of 4. Quote Link to comment Share on other sites More sharing options...
alortegac Posted November 28, 2016 Author Share Posted November 28, 2016 thanks, no more F18A are available. But thanks! Quote Link to comment Share on other sites More sharing options...
Bmack36 Posted November 28, 2016 Share Posted November 28, 2016 He does have them available, but won't be able to ship until after Dec 12. If you need one before then, I have a few extra I can sell. 1 Quote Link to comment Share on other sites More sharing options...
+5-11under Posted November 28, 2016 Share Posted November 28, 2016 thanks, no more F18A are available. But thanks! At the moment. I'm sure they'll be available again. I think he tends to build a handful at a time, as needed. Quote Link to comment Share on other sites More sharing options...
alortegac Posted November 28, 2016 Author Share Posted November 28, 2016 5-11, thank you very much. I will be checking for updates. Al Quote Link to comment Share on other sites More sharing options...
matthew180 Posted November 28, 2016 Share Posted November 28, 2016 They are still available, but I'm unavailable to ship them until Dec 12. I apologize for the inconvenience. I plan to make the F18A available until there is no longer any interest, which has not happened yet. In the meantime, you should take Bmack36 up on his offer since he has some for sale too. 1 Quote Link to comment Share on other sites More sharing options...
alortegac Posted November 29, 2016 Author Share Posted November 29, 2016 thank you very much for your response. I will do. AL Quote Link to comment Share on other sites More sharing options...
alortegac Posted November 29, 2016 Author Share Posted November 29, 2016 Chat45, why do you thing it look more a power issue than ram? What kind of power issue? Replacement of power capacitors? I could not clearly identify the problem in the screen pictures listed in the manual. They are not very clear but my console does not have scrambled characters only color dots and the grid. thanks! Quote Link to comment Share on other sites More sharing options...
chart45 Posted November 29, 2016 Share Posted November 29, 2016 this is why i think your problem could be the power switch or power suply.... ram chip will give you scramble graphic... like the image in the manual... but with the coleco you never know sometime you get weird stuff 1 Quote Link to comment Share on other sites More sharing options...
+nanochess Posted November 30, 2016 Share Posted November 30, 2016 It looks like a VRAM problem. When replacing the VRAM chips be sure to put sockets, the old chips tend to fail even when NOS (New Old Stock), but once you find a good set it can endure for decades. 1 Quote Link to comment Share on other sites More sharing options...
alortegac Posted December 6, 2016 Author Share Posted December 6, 2016 Just received the new ram. I will do the hack this weekend and report back! thanks!~ Quote Link to comment Share on other sites More sharing options...
alortegac Posted January 23, 2017 Author Share Posted January 23, 2017 (edited) Success!! Sorry it took me some time to report back, I have been pretty busy. Finally, yesterday I completed the replacement of the memory using the kit I purchased from Console5. Please see the pictures....It worked great. I also mod AV with my own kit as I was on it. Any feedback about replacing the BIOS chip with the NO DELAY BIOS? I did not do it because I honestly do not see much benefit vs. the risk of damaging the board in the process.......thoughts? Edited January 23, 2017 by alortegac 3 Quote Link to comment Share on other sites More sharing options...
SiLic0ne t0aD Posted January 23, 2017 Share Posted January 23, 2017 The BIOS mod isn't bad at all, not any worse than desoldering the old RAM, which you've already done and is a little more tricky IMHO. Other than desoldering and socketing, the only other thing you have to do is cut a couple traces and jumper a couple other connections. That's it, easy peesy! I have the press Fire intro skip BIOS and a no delay BIOS (skips completely), so there's options as far as that goes. Dual BIOS would be a cool mod but I've never tried that one (I posted a couple pics of it below). Anyways, it's not a hard mod, just take care when desoldering and cutting traces.. It's pretty much fool proof other than those 2 things. Good luck! Quote Link to comment Share on other sites More sharing options...
alortegac Posted January 23, 2017 Author Share Posted January 23, 2017 Thanks for all your help! I a really appreciate it. I still have double vision due to the 128 pins that I had to de-solder very carefully LOL.......I am going to purchase the IC and do the bios mod in a couple of weeks. thanks again also for sharing on the dual bios pics...honestly I did not know about it at all. Best of luck!! Al Quote Link to comment Share on other sites More sharing options...
EamonShoot Posted January 23, 2017 Share Posted January 23, 2017 The BIOS mod isn't bad at all, not any worse than desoldering the old RAM, which you've already done and is a little more tricky IMHO. Other than desoldering and socketing, the only other thing you have to do is cut a couple traces and jumper a couple other connections. That's it, easy peesy! I have the press Fire intro skip BIOS and a no delay BIOS (skips completely), so there's options as far as that goes. Dual BIOS would be a cool mod but I've never tried that one (I posted a couple pics of it below). Anyways, it's not a hard mod, just take care when desoldering and cutting traces.. It's pretty much fool proof other than those 2 things. Good luck! post-4311-1127585834.jpgpost-4311-1127585814.jpg Do you know if these boards are still available to buy and if so, where from please? Many thanks Sent from my iPad using Tapatalk Quote Link to comment Share on other sites More sharing options...
SiLic0ne t0aD Posted January 23, 2017 Share Posted January 23, 2017 I don't think that particular dual BIOs board is available anymore. I'm not sure who even made it.. I saved those pictures a long time ago after stumbling across it on the web. Wish I knew though, I'd have one myself. I think there's a different way to do it that's a little more crude but I can't really remember. I'd see what you can dig up through a Google search. Quote Link to comment Share on other sites More sharing options...
EamonShoot Posted January 23, 2017 Share Posted January 23, 2017 Ok - thanks for the reply. Sent from my iPad using Tapatalk Quote Link to comment Share on other sites More sharing options...
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