Colecovision problem needs help

[Trooper]

Ok, I've got two Colecovisions that I pulled out of storage yesterday to maybe sell of one of them since....well I need the money more than I need to Colecovisions

 

One of them works great so I put that away to keep. The other one...well I first thought I had problems with the controllers, but I've ruled that out after trying four different controllers of which three are working great in the other machine and one seems to be heading for a rebuild once I buy a new soldering iron. Anyway, the problem is that the fire button seems to be stuck in "pressed" position all the time. Like I said I first thought it was a problem with the controllers but since I've tried them in another CV and they all work fine it seems to be a problem in the machine itself. I opened it up but can't find any obvious shorts or any other problem that I can see with the naked eye.

 

What I'm asking is, have any of you had the same problem or do you know of it and know of a way to fix it? Otherwise the console works great, but when you start a game, you choose the difficulty and then the game comes on and the character jumps/fires once and then nothing, just as if the firebutton is pressed and not letting up.

 

Any help would be most appreciated!

 

/T

[+5-11under]

It looks like one of the 74LS541 chips inside are fried. Unfortunately, this is pretty common.

 

Thanks,

5-11under

[Trooper]

Should be easy enough to replace though?

[opcode]

Should be easy enough to replace though?

 

You need to remove the bad IC very carefully, because the Coleco PCBs are s*** and it's very easy to destroy tracks. Also, pay attention to IC orientation because the two 74LS541 are oriented in opposite ways.

[Trooper]

Ok, thanks for the help! I'll get on it as soon as my new soldering iron shows up.

[Bruce Tomlin]

You need to remove the bad IC very carefully, because the Coleco PCBs are s*** and it's very easy to destroy tracks. Also, pay attention to IC orientation because the two 74LS541 are oriented in opposite ways.

Yes, start by clipping the pins at the top, then you should be able to get them out without messing up the board. But then you will need to clean the holes, with either solder wick or something like Radio Shack's 64-2060 desoldering iron. (#1 rule: tin the tip before first use, #2 rule: expect it to erode relatively quickly and get a fresh tip for important projects)

 

Then install a socket. Of course you need to buy the chip before you do this, so buy two of them. If you can find a schematic, you can know which one is the bad chip before you start.