shear_xear Posted January 28, 2017 Share Posted January 28, 2017 Hi everyone, I have two ColecoVisions that have the same problem. When I turn on the power the screen is all black and there is (usually) a loud buzzing noise, I replaced the switch first, and then the video ram, but both times ended up with the same results. Is there anyone that has had this problem and been able to fix it? Thanks for your time! Mike Quote Link to comment Share on other sites More sharing options...
Pixelboy Posted January 29, 2017 Share Posted January 29, 2017 Are you using the same power supply block to test both consoles? Quote Link to comment Share on other sites More sharing options...
shear_xear Posted January 29, 2017 Author Share Posted January 29, 2017 I have a working ColecoVision and three or four power supplies that all seem to be working well (ie I have used them with the working console). I tried multiple power supplies with those that have this issue. Quote Link to comment Share on other sites More sharing options...
Crystallas Posted January 29, 2017 Share Posted January 29, 2017 (edited) Just some things to consider. Did you do the -5v delete on the memory, if so did you bypass? Are the traces on the VDP good? If so, is it passing current(in spec), if not, there is your answer. Edited January 29, 2017 by Crystallas Quote Link to comment Share on other sites More sharing options...
shear_xear Posted February 1, 2017 Author Share Posted February 1, 2017 What is the VDP? What am I looking for, and what readings should I expect? Thanks! Quote Link to comment Share on other sites More sharing options...
shear_xear Posted February 1, 2017 Author Share Posted February 1, 2017 And yes, I did the bypass Quote Link to comment Share on other sites More sharing options...
SiLic0ne t0aD Posted February 1, 2017 Share Posted February 1, 2017 Video Display Processor, the big chip with the heat sink on top. I'm not sure on the exact readings but you should see 5 volts I would assume. Quote Link to comment Share on other sites More sharing options...
omf Posted February 3, 2017 Share Posted February 3, 2017 Hi everyone, I have two ColecoVisions that have the same problem. When I turn on the power the screen is all black and there is (usually) a loud buzzing noise, I replaced the switch first, and then the video ram, but both times ended up with the same results. Is there anyone that has had this problem and been able to fix it? Thanks for your time! Mike you may want to get some new ram chips and try those, unfortunately those parts are the most expensive chips to get hold of on the main board. I had the exact same issue and changed many other components, but in the end it was one of the two ram chips that was bad Quote Link to comment Share on other sites More sharing options...
shear_xear Posted February 3, 2017 Author Share Posted February 3, 2017 (edited) @ SiLicOne t0aD85 I figured that was what you meant, but wanted to be sure (total noob here). I will check it out. @ omf I will see what I can do with that. I have two that have the same symptoms, so maybe there are two working between the pair thanks! Edited February 3, 2017 by shear_xear Quote Link to comment Share on other sites More sharing options...
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