cbmeeks Posted April 20, 2015 Share Posted April 20, 2015 (edited) So I bought two CV's off eBay for <$20 each. Both were reported not working. I managed to clean and mod the first one and it works like a champ. However, my second one isn't working correctly. My suspicion is bad memory. The unit powers up, the audio sounds fine but the screen is all messed up. But, it's messed up in a "bad data" type of way. For example, instead of saying "GET READY PLAYER 1" it says "GEP REAWY PCAYER 1". The game select screen says "PPRQQ @UTTML ML IEYPAD"...etc. (screen shots attached). So, what are your thoughts? I've cleaned it up physically. In fact, this was one of the cleanest units I've ever seen. Looks almost mint besides a little dust. All of the electrolytic capacitors are fine. Well, they aren't bulging and there is no leakage. I didn't take the RF unit apart to see if anything was leaking under it but I don't think that is the issue anyway since it isn't a bad picture for RF. Just looks like the letters have been replaced, colors swapped, etc. Thanks. Edited April 20, 2015 by cbmeeks Quote Link to comment Share on other sites More sharing options...
NIAD Posted April 20, 2015 Share Posted April 20, 2015 If the Power Switch has been cleaned and repacked with dielectric grease, then the issue you are experienced is due to one or more bad Ram chips. Head over to http://ann.hollowdreams.com and download the CV Technical Manual for details as to which RAM chip(s) might be the culprit. Quote Link to comment Share on other sites More sharing options...
+nanochess Posted April 20, 2015 Share Posted April 20, 2015 Yep, it looks like a VRAM memory failure. One of the eight chips is faulty. I don't see clearly which one. Quote Link to comment Share on other sites More sharing options...
NIAD Posted April 20, 2015 Share Posted April 20, 2015 When posting pics of issues with the CV, especially when you think it's a RAM issue, it's best to just use the CV BIOS screen (ie: no cartridge inserted). Quote Link to comment Share on other sites More sharing options...
Kiwi Posted April 20, 2015 Share Posted April 20, 2015 Probably bad vram. Probably memory range $1800-$2000, which holds the screen data, and sprite tables have gone bad. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted April 21, 2015 Author Share Posted April 21, 2015 Yeah, I was afraid of that. I might look into possibly replacing with SRAM. Of course that would be a major mod. Quote Link to comment Share on other sites More sharing options...
VectorGamer Posted April 21, 2015 Share Posted April 21, 2015 Is this fixable? I have a CV that may have the same issue and want to know if it's possible to have it repaired. Quote Link to comment Share on other sites More sharing options...
NIAD Posted April 21, 2015 Share Posted April 21, 2015 Is this fixable? I have a CV that may have the same issue and want to know if it's possible to have it repaired.If you are not comfortable desoldering the old chips and then soldering new sockets in place for the repacement chips, then Yurkie is the man to contact. Quote Link to comment Share on other sites More sharing options...
Vectorman Posted April 21, 2015 Share Posted April 21, 2015 Try a different power supply before you go desoldering memory chips/power switches. CV's are very picky about PS's and sometimes work perfectly with one and are glitchy with another. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted April 22, 2015 Author Share Posted April 22, 2015 I only have one power supply. But it's confirmed working. Anyone know of any SRAM replacement mods? Quote Link to comment Share on other sites More sharing options...
NIAD Posted April 22, 2015 Share Posted April 22, 2015 I only have one power supply. But it's confirmed working. Anyone know of any SRAM replacement mods? http://www.arcadecomponents.com/index.html The F18A VGA Video Upgrade also replaces the built-in RAM of the CV: http://codehackcreate.com/archives/335 1 Quote Link to comment Share on other sites More sharing options...
CrazyBoss Posted April 22, 2015 Share Posted April 22, 2015 its something with bit 1 ? bit 1= 2 decimal. S is shown as Q 2 is shown as 0 K is shown as I what is common for those is if you take the ascii value of the lette should be shown, and set bit 1 to 0, (minus 2 if you want), then you get what is show on the screen. But not sure what its is cause if the vram was bad bit 1 always=zero, then i would suspect sprites and letters and other graphics to be bad too. Quote Link to comment Share on other sites More sharing options...
Vectorman Posted April 23, 2015 Share Posted April 23, 2015 This kind of crap is why we need that CV 1.2 project now more than ever. All the CV's out there are probably toast by now. I considered buying another CV off ebay but I'm too tired of dealing with these problems. Quote Link to comment Share on other sites More sharing options...
NIAD Posted April 23, 2015 Share Posted April 23, 2015 This kind of crap is why we need that CV 1.2 project now more than ever. All the CV's out there are probably toast by now. I considered buying another CV off ebay but I'm too tired of dealing with these problems.Then you should buy an ADAM. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted April 24, 2015 Author Share Posted April 24, 2015 I have an ADAM. Love it. But the damn thing takes up half my office. Lol. My dream is to build my own "CV1.2" like console. It would be driven by a propeller for video and other things with a real Z80. Just need to get off my butt and build it. Lol Quote Link to comment Share on other sites More sharing options...
Pixelboy Posted April 24, 2015 Share Posted April 24, 2015 My dream is to build my own "CV1.2" like console. It would be driven by a propeller for video and other things with a real Z80. Just need to get off my butt and build it. Lol So we're talking about something like this? Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted April 26, 2015 Author Share Posted April 26, 2015 Bingo. It would be that exactly. Quote Link to comment Share on other sites More sharing options...
jackrabbitslim13 Posted May 16, 2015 Share Posted May 16, 2015 My colecovision does the same thing, missing letters at the start screen and garbled graphics, but the expansion module 1 (Atari games) works great. I've cleaned and greased the power switch, so does that mean I have a bad chip? Quote Link to comment Share on other sites More sharing options...
+Yurkie Posted May 17, 2015 Share Posted May 17, 2015 You guys are welcome to send your console for repair send me a pm. Quote Link to comment Share on other sites More sharing options...
cbmeeks Posted May 17, 2015 Author Share Posted May 17, 2015 I think I have identified two bad 4116 RAM IC's that I hope to replace tomorrow. Thanks. Quote Link to comment Share on other sites More sharing options...
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