RTBaker Posted June 6, 2017 Share Posted June 6, 2017 Hi, I have just spent a few weeks bringing an old ColecoVision back from the dead. It was a flea-bay purchase and had a dead power supply, faulty video memory, a dodgy power switch and a broken cartridge connector!. Anyways, I have replaced the memory - now 5V only, repaired the power switch, replaced the cartridge connector and it now runs OK from a 5V power supply with a 5V to 12V (Pololu U3V50ALV) up converter inside the case. The problem I now have is that I am getting vertical lines on the sprites as shown in the attachments. Its fine when the games startup in text mode but appears as soon as a sprite is present. I have attached some photos of the problem. Can anyone help and point me in the direction of the problem please? Thanks very much for your help. 1 Quote Link to comment Share on other sites More sharing options...
R.Cade Posted June 6, 2017 Share Posted June 6, 2017 Looks like a stuck bit in VRAM. Quote Link to comment Share on other sites More sharing options...
+-^CrossBow^- Posted June 6, 2017 Share Posted June 6, 2017 Was going to say something similar. Since you upgraded/replaced the vram. Double check all of your connections and traces. I won't lie, I killed 2 other CVs before I was successful in doing the +5 ram upgrade. The damn traces just come up so easily and damn near impossible to track down and fix after the fact. Quote Link to comment Share on other sites More sharing options...
RTBaker Posted June 6, 2017 Author Share Posted June 6, 2017 Thanks for the advice - I'll try to double check all the traces with a multimeter to check continuity between all the VRAMs Quote Link to comment Share on other sites More sharing options...
7800fan Posted June 7, 2017 Share Posted June 7, 2017 I hope you made those RAM socketed, if you soldered the RAM and you had to resolder, you risk more damage to the fragile traces. When I did my mod, I used my meter and tested from the top of the chip's pins so I could both verify the connection is good and to find bad trace or just bad socket connection. All of the address lines are the same but data lines are separate. A lot of probing but saved me the trouble later on when I found a couple broken connections. Quote Link to comment Share on other sites More sharing options...
towmater Posted June 7, 2017 Share Posted June 7, 2017 F18A time now is here. I would hope one would solve all of your problems as it has it's own video ram. Quote Link to comment Share on other sites More sharing options...
RTBaker Posted June 7, 2017 Author Share Posted June 7, 2017 I did put in sockets so I was able to check out all of the memory lines between the memories and to the graphics chip - they were all OK. I then thought to check out the power supply I was using and found that it tops out at 500mA so I changed it for the 1.5A unit I use with my Raspberry Pi. With the new power supply all is well and all of the lines have disappeared! Thanks very much for all the suggestions and help Quote Link to comment Share on other sites More sharing options...
DadsGlasses Posted June 7, 2017 Share Posted June 7, 2017 Seems like "Power Supply" is the solution to almost all ColecoVision problems! Glad you got it worked out. 1 Quote Link to comment Share on other sites More sharing options...
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