Colecovision with new 74ls451's & bios skip mod acting up

[Shawn]

Hey,

 

So my 74ls451 blew (fire buttons didn't work on controller 1 with a good controller). I removed the old chips,

installed sockets and replaced the chip but now the system is running the bios screen and then crashing.

It shouldn't be doing this as the BIOS I have installed is the skip wait screen version that should just be jumping

to the game selection screen which it was doing just fine prior to removing and replacing the 74ls451s.

That is the only thing I've done since it was in full working order. Anyone know what else could potentially

have blown or gone wrong to cause this? I'm totally new to colecovision hardware so I'm learning as I go.

 

There was a couple traces that broke when I was removing the old 74ls451's but I fixed them with some

IDE cable as you can see in the pictures of the motherboard attached. I have cleaned the power switch

and it works as it should. I thought that was worth adding. Thanks for any and all help in advance.

 

Shawn

 

 

[Shawn]

Is there more of the population I should replace perhaps?

[Shawn]

Fixed it It was those sockets I installed. They where both oxidized. I replaced them with fresh ones from Digikey today and now all is well Lesson learned here? Don't buy sockets from China that have sat for decades getting crusty.

[+-^CrossBow^-]

And I would advise against using machine pin sockets for IC chips with flat legs. When you do that, you are really only making contact with the legs from the edges of them. Always use dual wipe sockets for IC chips.

[mobiusstriptech]

While you are in there. You should clean that green cartridge contact as well.

[Shawn]

While you are in there. You should clean that green cartridge contact as well.

 

Didn't even notice that till you pointed it out! Thanks so much for noticing. I'll be sure to do that ASAP.

[mobiusstriptech]

Yeah I was looking at the wiring fix and saw it in the corner of my eye. Always better to fix that stuff before it gets too bad.

[CrazyBoss]

I just replaced all the vram ics, and put sockets. It seems the easies way to deal with the colecovision mainboards will be to cut the pins, and desolder from both sides using solderpump. I broke a few traces but it was an easy fix also installed a dirty composite fix using a resistor and a transistor

 

I did the same with the controller ics a few years ago i did not break any traces that time