2 Colecovisions Experiencing Same Type of Display Problems

[tbishop2]

I have two ColecoVisions at my house that have bad displays. I have put the new switch mod on both, but seem to still be experiencing problems. The second image, 20.26.50, is what my oldest board is doing. I have found the R62 resistor to be around 1600 ohms instead of what is required. So I will start there

 

The 19.46.23 image is what the newest board is displaying. Any ideas of where to start would be appreciated. My diagnostic tools are archaic at best. I do have a volt meter, but I do not believe it will check farads on caps.

 

These are fun to tinker with as long as you're making progress.

 

 

[+Yurkie]

I'll start by saying "Please NEVER EVER replace the original power switch" A cleaned and refurbished switch works perfectly for years. I have done many hundreds over 6 years and never had a repeat problem.

 

I'm also not a "diagnose over the internet person". That said. I think either TV is not compatible or your on the wrong channel, meaning tv and colecovsion channels are not set to the same channel. There is a 3/4 channels switch on the back of the CV.

Edited November 30, 2016 by Yurkie

[+nanochess]

Before anything check voltages with a multimeter, 5V+, 5V- and 12V+, these must be within 5% tolerance.

 

Put a composite jack with side grounded and center connected to pin 36 of Video Display Processor.

 

You can connect this directly to your TV, if it shows a steady video frame then your VDP is right and the culprit is your RF module.

 

Otherwise you'll be better replacing your VDP chip, I recommend strongly putting a socket.

[tbishop2]

As ashamed as I am to admit it. Apparently they were both on Channel 4 output. I know Id tried that. See attached pics for what they look like now. THanks much for the help. The one with the clear Colecovision will not take ANY input from controller 1, is there a game where i can try controller 2, and yes Ive ordered a new controller chip for them both.

 

The newest board is displaying badly. Which ROM chips do you believe I need to get, or get them all? Thanks so much for all the help. You guys are awesome.

[+nanochess]

Congrats on getting one to work! I recommend to use isopropilic alcohol to clear the channel switch, just spray and switch several times.

 

I suggest strongly to change all VRAM memories (4116), if you don't have soldering abilities, Yurkie is pretty good for doing it.

[NIAD]

Make sure to put a socket(s) on the PCB for the Controller IC(s). These chips are known to go bad especially when swapping controllers with the system on... so always turn off and even unplug the system when plugging/unplugging controllers.

 

Most Coleco games offer two player modes and Donkey Kong is a good choice for starting a game with controller #2.

 

The system that is displaying the corrupt ColecoVision BIOS screen has one or more bad 4116 Vram chips. You can isolate which one(s) by comparing your screen to what is shown in the CV Technical Manual. Add sockets as was suggested.

[tbishop2]

OK, new Controller IC's installed, and still have the same issue, the blue player select screen skips and mario walks to the right w/o any input. This system also starts up at a black screen with a hum, and you push reset to get it started.

 

The newest board now has all new sockets and memory chips installed. Attached is what it looks like. I can seem to place the display to the tech manuals display. Any more ideas?

 

 

[tbishop2]

Im not getting the 5 volts on the one with bad display at my memory chips. Something like 4.45v, could this be the problem.

 

When I check the voltage on the one that wont control, on pin 1 of controller chip one it freaks out the coleco...bad. Where does this lead go to? It may be a damaged lead.

Thanks,

[tbishop2]

Troubleshooted the heck out of the newest board, the one that says CO...ON, and had a short on one leg. Wow. Came on, and worked like a charm after that.

 

Still looking to get the one with the control issue to working.

[tbishop2]

Both now working. Holy crap what a feeling. Second one had a bad lead from line 1 on controller IC to line 1 on second controller IC. Learned alot about these old machines. Now on to Super Action Controllers. Anyone know where to start on these when they wont do anything but make the guy go left/right?

[NIAD]

Congrats on getting the two systems working. After you replaced the respective chips with no success, the obvious problems to check for were shorts and damaged traces.

 

Re. the Super Action Controller, there was a very good thread that discusses repairing directional issues if a good cleaning doesn't solve the issue. Usually means a broken/cracked plastic ring that is under the joystick and presses down on the contacts on the PCB. Think I recall there being mention of a replacement that can be used. You'll have to use the forum search option to find the thread.