Coleco Vision controller port problem...

[Heidi]

My Coleco Vision's controller port 1 has malfunctioned. The gameplay is always moving left, irregardless of whether the controller is plugged in or not. Any suggestions?

[FABombjoy]

Sounds like this problem:

http://www.classicgaming.com/colecofaq/#13.3

[ianoid]

I have this problem. Kills me since I have this issue with an AV modded CV. I have to decide whether to repair it or buy a new AV mod and junk it. For posterity, here is the section from the FAQ:

13.3) To fix an automatic level select problem:

One possible piece which can be blown by static electricity at the controller ports (see 10.2) is the SN74LS541N chip, a 3-to-8 decoder. If this is the chip that's blown, then replacing this chip (a generic component, available at any good electronics store) can solve the problem. - 13, 15

Parts:

A good soldering iron (with a very thin tip) Computer solder (thin) Solder wick Needle nose pliers An SN74LS541N chip Two 2.2K K27 resistor packets (optional/recommended)
Getting started:

Plug in and turn on the Coleco with a Donkey Kong cart inserted. When the game automatically goes into play mode, note if the Mario moves without touching the joystick. If so, then the 1st player chip is definitely damaged. If a two player game is the one automatically started (which seems to be the prevalent fail mode) automatic movement of the second player's Mario likewise indicates that the 2nd player chip is certainly damaged. Lack of automatic movement does not rule out the possibility that either or both chips are damaged; indeed, given the automatic select problem, it's likely that at least one chip is damaged. But determining that one chip is certainly damaged can minimize your work.

Surgery:

1) Turn off and unplug your ColecoVision, removing the cartridge.

2) Make certain that you are properly grounded, if possible.

3) Open the plastic casing for the unit.

4) Remove the metal cover from the board by desoldering it. It just gets in the way so its better to remove it. It is not essential to the working of the game, though it can be resoldered later if desired.

5) the bare board upside down and find the soldering connections for the SN74LS541N chip that you wish to replace.

6) Note the orientation of the SN74LS541N you intend to replace, so that you can be certain that you provide the same orientation for the replacement chip.

7) Take the soldering iron and solder wick. Place the wick on one of the solder connections on the board. Press the solder iron on the wick. The iron will heat up the wick which will heat up the solder. The solder will turn liquid and be absorbed by the wick. This takes some practice before you get the hang of it.

8) Absorb as much of the solder as possible from all of the connections to the chip you're removing as possible.

9) Flip the board back over and take the pliers. This is where you have to get tough with your Coleco, and let it know who's boss! Growl at it occasionally to let off steam. Now, being careful not to harm any other components on the board, grip the defective chip with the pliers and pull and pry. It's OK to break the chip because it's defective garbage anyway.

*** Note - it's a good idea to wiffle each of the pins to pop them off any remaining solder. In fact, if the chip really is dead, it's better to just snip or Dremel all the pins off first, _then_ desolder the pins individually. - 29

10) After forcibly removing bits of the defective chip from the board, remove any broken pins stuck in the board, extra solder, etc. so that the area that was occupied by that chip is clean. Suck up the solder from the pinholes with the wick so that you can see right through the board through each pinhole. Gee, your ColecoVision never looked better!

11) Take the new SN74LS541N chip and gently install it in the board, inserting the pins in the pinholes. Make sure that the chip is oriented in the same direction that the original chip was! Gently bend the pins if necessary so that they all go in the holes. Be careful not to press too hard as you might bend some pins that aren't properly aligned with their holes.

12) Flip the board over. Take the solder iron and the computer solder and solder each connection carefully. Isn't this fun? Don't you feel like a computer technician now?

13) Optional/recommended: Replace the resistor packets on the port in a similar (though much easier) manner. For these parts, note the DOT orientation when replacing.

14) Put the board back in the plastic case to avoid shock.

[FABombjoy]

It's a 10 cent chip - don't junk the console.

Those are some wordy instructions there, and step 9 could cause more problems than it solves. On a professionals workbench, steps 7-10 would be encompassed by "use desoldering tool to remove chip", total time: 1 minute.

If I didn't have a desoldering tool, I'd just clip the legs and solder the new chip to the old legs. Total time: 1 minute. No reason to use solder braid.

[ianoid]

Any suggestions as to where to buy this chip most reasonably in small quantity (um, fewer than 4?) Also, where to get supplies online cheaply? I could use a fan and a positioning arm. I could use some of that braid, maybe a good fine tipped soldiering iron (I have one that might work, but I don't even know how to take care of it- tinning?).

Any good videos online you can suggest for use of braid and desoldiering?

Not being able to solder properly is a major issue for me. I have nobody to show me in person how to do these things. I know it's not beyond what I could do, but without appropriate tutelage, it's hard to know what these simple jobs are supposed to look like. I could guarantee this would take me an hour, since I don't know what I'm doing.

[FABombjoy]

eBay can be a good source of cheap, low quantity ICs. There are a few suppliers that send first class too, although the particular ones escape me.

I'd say that you can completely skip the desoldering part. Get a good pair of small diagonal cutters (the kind that come to a point small enough to fit between the chip legs), and cut the legs off the old chip. Then solder the new chip to the old stumps left in the board. It'll work just the same, and it will spare you the agony of desoldering with braid (especially on a Coleco board which are easy to damage this way if not done correctly).

For videos on soldering basics... I'll bet youtube has a few.

[doubledownon11]

Personally I've performed this repair more than a couple dozen times. I simply clip the pins of the IC, and desolder each pin individually; that way there is little to no risk of pulling a trace off of the PCB. Then I use de-soldering wick to clear the through-holes. Once removed and cleaned you can solder in the new Octal Buffer, or in my case I solder in a socket, and install the IC into it. That way, if in the future the failure happens again, the repair is simple. If anybody looking for these ICs, I believe I get mine from Digi-Key. They may have a $20 minimum order, I can't remember. Normally I'm ordering a stash of them and/or other stuff, so it's never been a problem for me.

[Compute]

Bump..

I am presently having problems with my Colecovision. Player 2 direction Left does not work right not. I haven't done any diag work yet. Is the same part listed in this thread/repair a likely culprit? I've tested it with several known-good controllers already. Thanks!

[channelmaniac]

If it's acting like you are moving when the stick isn't moving then replace the bad 74LS541 chip.

If it's not registering the move when you move the stick then look for bent pins on the controller port, cracked solder on the controller port, or replace the 74LS541 chip.

I have a bunch of those in stock.

RJ