Colecovision screen glitches

[Tpapp54321]

I finally finished the power supply on my Colecovison but after testing games I've noticed that on almost EVERY single game there is a small screen glitch that will appear. I know for a fact that it's not the power switch as I rebuilt it already.Most of the glitches are just a colored box or two added to the screen, or sometimes the game characters will be slightly misshape. The only exception is Frenzy, it has a line of letters that go down the left side of the screen. Also, unlike the other glitches this one affects the gameplay. Usually you can pass/walk through the glitch zones but this one blocks you in. The major thing though is that the glitches are the same glitch every single time and each game has its own unique problem. I've touched up some of the solder joints that looked bad but that didn't help either. What do you guys thing is the problem? I'll try and add some pictures of the problem too

[Tpapp54321]

Glitch in Frenzy that prevents you from playing the game by trapping you inside the letters.

 

Small glitch in time pilot around the square telling the date.

 

Glitch in Zaxxon where there are three random blocks following you.

 

ALSO: The loading screen is always displayed crorectly, never with misspellings or a garbled image.

Edited May 7, 2016 by Tpapp54321

[+nanochess]

It looks like a RAM failure.

[Tpapp54321]

Well, darn. I was hoping it was something else like a capacitor ( I've got plenty of those). How difficult would it be to upgrade the RAM with a kit like this? http://console5.com/store/colecovision-5v-memory-upgrade-kit.html I have experience in soldering but the solder pads on the CV board are so darned fragile. Is it possible to just cut the existing chips and solder the socket legs to the legs from the old RAM chips?

[7800fan]

You can do that, leave the old pins in and solder new chip or socket on top of it. But I'd suggest letting an expert do the mod, it is easy to ruin the CV board by looking at it the wrong way.

 

I am an expert on soldering and I still had trouble with my CV. After the RAM mod, no intro BIOS, replacement cart connector, and AV mod I still had to run a couple wires to repair damaged traces.

[Tpapp54321]

How much would it cost to have someone do the work?

[toiletunes]

Yurkie does Coleco stuff, I'd look him up in the sales forum and send a pm.

[Tpapp54321]

UPDATE:

I've been told that it might be that the VDP is bad. I'm going to order a replacement and hopefully get back with good results.

[Tpapp54321]

Hello, me again. Finally found the time to do some soldering and desoldering and I now have the chip sockets installed. However I am confused on which direction the chips go in? I don't want to screw anything up but am really confused. There's no notch in the chip but there is a dot (signifies pin 1?). I got my chips from console5.com if that helps.

EDIT: here's a picture with the two possible chip orientations. With the "revision f" facing the top, is the left side or right correct?

https://ibb.co/fAvyX5

Edited July 23, 2017 by Tpapp54321

[7800fan]

White dot marks pin 1 of the chip, and should be closest to the notched side of the socket and silkscreen. So the right side chip is in correct position. Left side chip is backward.

[the_crayon_king]

I would bet money that the chip was fine and it was a dry solder joint someplace.

Be sure to try the old chip beforehand and let us know. Likely fixed the issue when adding a socket.

 

A way to test for goofy stuff like that is the poke around with a bit of plastic while the console is on.

Pressing on the area with a dry solder joint will often complete the circuit.

 

I see dry solder on so many varied consoles but the coleco is one of the worst.

Edited September 24, 2017 by the_crayon_king