Glen's Retro Show Posted June 22, 2016 Share Posted June 22, 2016 Hi everyone I have two three ColecoVision three power supplies. My first ColecoVision works perfectly my other two ColecoVision will turn on go to the select game mode screen and do one of two things either lock up and go to a black screen or a quick flash of green then a blank screen or the game will start then freeze and go back either to the main ColecoVision bios screen or just freeze. Now I've checked the power supply units on all three with a multimeter all are supplying the correct voltages and both that are doing the issue I have installed an F-18 a to eliminate any issue with the video RAM I have even taken an ATX power supply and supplied 12 volts 5 volts and ground same issue so I can definitely rule out the physical power supplies I have cleaned the cartridge connector many times I have replaced the on-off switch entirely thinking that would be the cause I have Reflow the solder on the processor the BIOS the cartridge slot and reinstall the f18a there are times for letting him sit long enough the game will play for a minute sometimes I play for a while other times turning it on he could to ColecoVision welcome screen then reasons for green screen freezes or reboots I'm about to really give up on these two units I invested way too much time and I'm at a loss if anyone seen something like this or has an idea it be greatly appreciated thank you Quote Link to comment Share on other sites More sharing options...
Glen's Retro Show Posted June 22, 2016 Author Share Posted June 22, 2016 Hi everyone just looking for some Clues and maybe some assistance on an eBay non-working ColecoVision I've done some work on please have a look at the video and let me know if you have any suggestions on what could be causing the sporadic freeze ups and resets I have check the powersupply I have 3 of them all powersupply showing correct voltage I've even used a IBM ATX power supply just to confirm again all power supplies I'm good cleaned and replaced power switch Reflow the solder and even clean the carpets port still at a loss as to why it's glitching Quote Link to comment Share on other sites More sharing options...
mightywiz Posted June 22, 2016 Share Posted June 22, 2016 maybe it's your f18a 2 different system, same f18a used in both units? if so then it's the f18a causing it Quote Link to comment Share on other sites More sharing options...
Glen's Retro Show Posted June 23, 2016 Author Share Posted June 23, 2016 Its a possibility..but it was first doing it with the original,vdp in both too. Why its so hard to isolate... Quote Link to comment Share on other sites More sharing options...
Glen's Retro Show Posted June 23, 2016 Author Share Posted June 23, 2016 Just to test I remove the f18a and since I have a socket there now I put in the original video display processor I was able to get further play a little bit of the game for maybe about a minute but then sure enough the machine blacked out now with an Atari Max cart and and running a member utility it does show that the internal Ram is ok it also said the same thing when I had the f18a installed butt again it's still locks up just goes a little bit further along with the standard video display chip Quote Link to comment Share on other sites More sharing options...
Kiwi Posted June 23, 2016 Share Posted June 23, 2016 My Colecovision will go to a black screen after a minute or so if you don't touch the controls. It will turn back on when you move the joypad. It is a screen saver feature of the OS7 I believe to prevent the vdp chip from burning out. If you use a Atarimax Ultimate SD cartridge and let it go to a black screen, I think it cut the power to the cartridge so the SRAM or something holding the ROM image get wiped out and it'll reboot. That was my case. It has to be a static screen of a Coleco made games. Just pointing out that out to make sure it does go to a blank screen after few minute of inactivity on a unmodified console, and shows back up when you move the joypad. I don't know the behavior if a F18a is attached to the unit and the screen saver mode go into action. If you're playing the game and the video cuts out, then I would worry. Quote Link to comment Share on other sites More sharing options...
Glen's Retro Show Posted June 23, 2016 Author Share Posted June 23, 2016 Yes it's doing a real cartridge Venture Donkey Kong ladybug but also with the Atari Max and I know the screen save feature but when you press the key the screen will come back when this goes to a black or green black screen you usually have to power off and wait and it'll turn back on in a few minutes maybe could take longer could take less it's just weird that I got two consoles from eBay that pretty much doing the exact same thing my original works perfectly fine usually when something happens like this it's a power issue but using 3 official power packs and one ATX power supply voltages all voltages were correct 5 volts 12 volts and I needed now but also have -5 volts all within spec, be overheating however I checked for that as well it could also be a bad capacitor but I don't see any fault with them Quote Link to comment Share on other sites More sharing options...
cdn2a Posted June 23, 2016 Share Posted June 23, 2016 I'll reiterate some very good advice, I was given. This has helped me fix a bunch of colecos. ok, I watched you video. Isolate the issue, is it processor / bios / sram issue? or VDP / vram issue? Get yourself a frogger cart. (This is really helpful when it's a total black screen, no bios) Boot it, and see what happens. If the music etc powers on and screen stays blank, then its towards Vram VDP issue. (I'm pretty sure this isnt your issue, since bios posts proper) If the music cuts out same as video then it's towards processor bios etc... (The green screen I'm fairly sure is the monitor when video signal drops out. Normal, after a few min video drops if no selection. Try on your working one.) Remember the controller buffer chips are on the same bus as the bios. If the controllers are unresponsive this is where I would go next. If you can socket the VDP you'll have no prob pulling the buffer chips. Pull 1, socket it, on your working machine. Then try the chips from your non working machine, in the working one. That way you can test and not guess. My test mule coleco is fully socketed for just this reason. Post back and keep us updated. Quote Link to comment Share on other sites More sharing options...
Glen's Retro Show Posted June 23, 2016 Author Share Posted June 23, 2016 (edited) Cdn2a. Thank you..some good ideas... Will try them. I can say for right now with running venture and Gorf in space panic.. They all seem to do pretty much the same thing send to work perfectly fine sometimes play perfectly then just freeze up or a quick freeze and resets back to the BIOS screen and then usually when I get to the BIOS screen either it'll just keep rebooting back to the BIOS screen instead of going to the menu select or a green screen full colors now as far as the video RAM when the original video Display processor is in I could say yeah that could be the case with vram but when the f18a is in it's completely bypassing that so my thoughts are now to be static Ram or possibly even a CPU issue and I guess I can go to start putting them in a socket Edited June 23, 2016 by moonlight23 Quote Link to comment Share on other sites More sharing options...
cdn2a Posted June 23, 2016 Share Posted June 23, 2016 What does it do with the standard VDP? Quote Link to comment Share on other sites More sharing options...
Glen's Retro Show Posted June 23, 2016 Author Share Posted June 23, 2016 Sorry.. VDP = Video Display Proccesser Quote Link to comment Share on other sites More sharing options...
cdn2a Posted June 23, 2016 Share Posted June 23, 2016 yes Quote Link to comment Share on other sites More sharing options...
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