I could use some help with a Colecovision....

[sanman]

Hello all before i start just wanted to say nice site looks like it can be helpful to many people..Well my problem is that i've been wanting a colecovision for quit some time looking and searching on ebay. Well i found one that was like brand new in box bought it as is,not tested,no returns figured it would work on a never played item guess what i was wrong. Overpaid paperweight.....Now i plug in and nothing white snow, seems like the power supply is not even plugged in the power supply seems to warm up when plugged into the wall for a while so i guess thats not the problem. can someone please help me troubleshoot this. Is there a way to make sure power supply is working before i spend any more dough on this bad boy.. Any suggest would be greatly appreciated. like a guide on troubleshooting for dummies thanks..

[Ian Primus]

One thing I've seen many times on Colecovisions is that the power connector on the console gets flakey. Press in firmly, see if it does something. Ensure that you have the TV on the correct channel. You should get the COLECOVISION splash screen even if no cartridge is inserted.

 

The power supply puts out three seperate voltages. To test it, you can just use a voltmeter. The pinout is:

 

1 +5VDC

2 -5VDC

3 +12VDC

4 Ground

 

Are you sure you've got everything hooked up right? Check the simple things, like that the switchbox is good, and is set to GAME, and that the TV is on the right channel.

 

-Ian

[sanman]

Well everything is hooked up right because my intellivision is working with the same switch . dont know how to use a voltmeter i tried a light tester didnt work though guess not enough juice.

[Ian Primus]

If you can't get it to do anything at all on the screen, it could be either the console or the power supply. The consoles do tend to get flakey power connectors and I've also seen some dodgy power switches too. Turn on the console with no game and no controllers. Plug it in, and wiggle the power connector slowly back and forth, see if you can get some life at all (screen should flicker, go black - or the console should come on). If it's still nothing, then press in on and forward on the power switch, and wiggle that a bit.

 

If still nothing, you should start by ruling out the power supply. Do you have a friend that might have a voltmeter?

 

-Ian

[sanman]

No but i will go out and get one today if needed to tell you the truth i did try everything you said moving the switch back and forth and nothing happens no flicker on the screen.How do you test with voltmeter i am very handy should be no problem if you can tell me how. Thanks..Any way you think it could be power supply even though it does get warm when its plugged into the wall.

[Ian Primus]

How do you test with voltmeter i am very handy should be no problem if you can tell me how.

 

Set the voltmeter to DC volts. If you've got a model that doesn't autorange, set the dial to the "20VDC" setting. Plug the AC adapter into the wall, but don't plug it into the Colecovision. Put the black probe from the meter into pin 4 at the end of the AC adapter's cable (I believe they're numbered with tiny numbers molded into the plastic plug). This is ground. Then put the red probe into one of the other pin recepticles on the connector. The voltages should come close to the ones listed earlier - although I'd expect them to be a bit higher. That's an unregulated supply, so with no load, the voltages will read kinda high. The key is that you're getting power. If you have an analog meter, the -5v will simply peg the meter on the left side, so to measure that one on an analog meter, put the red probe in the ground pin, and the black one on the -5v. This will make the meter display a positive reading. A digital meter doesn't need this reversing, since it can register negative voltages.

 

Thanks..Any way you think it could be power supply even though it does get warm when its plugged into the wall.

 

The adapter gets warm because the primary of the transformer inside is always connected to the wall. The secondaries are connected to the rectifiers and filter caps (the things that fail). The transformer will get warm wether the secondaries are connected to anything or not. I do not remember if the power adapter is fused, but I somehow doubt it - most are not.

 

-Ian

[sanman]

Thanks i'll try that later have to go to work and pay the bills . Get back to you tomorrow thanks for your time..

[sanman]

Well i tested the power supply with the multimeter my results are

 

 

Colored wire

 

black = ground

red = 2.50 - 5.75 keeps jumping not stable

blue = -5.11

white = 5.14

 

i guess red should be pegged at 12 or so could this be my problem power supply no good ??

[Ian Primus]

Well i tested the power supply with the multimeter my results are

 

Colored wire

 

black = ground

red = 2.50 - 5.75 keeps jumping not stable

blue = -5.11

white = 5.14

 

i guess red should be pegged at 12 or so could this be my problem power supply no good ??

 

I take it you cut the power cable, or opened up the power supply brick? Or are you measuring something inside the Coleco itself?

 

Yes, all outputs should be stable, and read DC volts. The blue and white wire readings are correct. Try setting your meter to AC volts and see what you get on that weird one. You might get a solid reading that way - which is not good. It should be DC.

 

It sounds like a rectifier in the power block failed. You can repair it if you can get the power block open.

 

Hopefully the Colecovision itself wasn't damaged from using this supply. It's been a while since I was in one, so I don't remember the power regulation circuit.

 

Another altenative is to patch in another power supply. The power supply from an old PC will put out all the voltages you need - look for the kind of supply with the ON/OFF switch (AT style), as opposed to the 'soft power' switch (ATX).

 

 

-Ian

[sanman]

I took the brick apart how can it be fixed ... i did try ac reading was 1.9 steady i guess that is not the problem.

i read somewhere i think here to resolder all cracked solder joint but i dont see any crack, looks good. any suggest

would be great on this repair.Buy the way Ian my name is Fred

[Ian Primus]

I took the brick apart how can it be fixed ... i did try ac reading was 1.9 steady i guess that is not the problem.

i read somewhere i think here to resolder all cracked solder joint but i dont see any crack, looks good. any suggest

would be great on this repair.Buy the way Ian my name is Fred

 

The AC reading is not good. You should get nothing when you switch over to AC. I've never actually been inside the official Colecovision power adapter, so you're in new territory for me - but I've fixed enough of this type of thing to know what's going to be inside it.

 

Follow the red wire back to the circuit board. It should be connected to the positive terminal of an electrolytic capacitor (looks like a can with a label - what does the label on this one say? It should list a rating in 'uF', and a voltage rating). Following that trace on the back of the board, it should be connected to some diodes (or a potted rectifier... but probably diodes). The diodes are little black cylindrical things, with a silver stripe on one end. Two of them should be connected to that trace that's connected to the red wire/positive of electrolytic. Set your meter on AC, and measure with one probe on the opposite leg of each of those two diodes - the legs that AREN'T connected to the red wire/electrolytic. You should get a good solid AC reading of somewhere in the vicinity of 12v from this point.

 

If you do, then the transformer is good, and you have a problem with either the diodes or the capacitor. Start by carefully examining the solder points on the back of the board for cracks - but it sounds like you've done this already. Post the numbers you find on the capacitor here - and I can direct you to a replacement (should be available from Radio Shack). The diodes should also have number on them, but they should be replaceable by the generic 1n4001 diode. You can get these at Radio Shack too. Total cost for all the parts should be under five dollars. When replacing parts, be careful of the polarity! Both the diodes and the capacitor must be installed the correct way around!

 

Can you post pictures?

 

I'm going to go hunting on the 'net and see if I can find schematics of the Coleco power adapter. Once again, I've never opened one of these, so I'm going on knowledge of other AC adapters. The Coleco adapter puts out multiple voltages, so I'm not 100% sure what I just mentioned will match yours. A good photo of the inside, the top of the board, and the bottom of the board will provide me the info I need.

 

-Ian

[sanman]

Ian your the man i took apart the power supply traced the red wire back to a some part it says 1A bent it a little and bingo its working 12.45 pegged i just have to figure out why ill try soldering that piece back hopefully it will cure it thank you very much.

[Ian Primus]

Ian your the man i took apart the power supply traced the red wire back to a some part it says 1A bent it a little and bingo its working 12.45 pegged i just have to figure out why ill try soldering that piece back hopefully it will cure it thank you very much.

 

Yay!

 

Glad you got it working!

 

Probably a cracked solder joint on the back of the board. This is pretty common on devices like this - what happens is the components sit there and cook inside that little box, then tiny cracks start to form in the solder joints. Sometimes you can't hardly see them, but it's enough to make things not work.

 

Just reheat the connection with a soldering iron and flow in a bit of fresh solder. Touch up any other joints that look suspect while you're in there.

 

Now, go play some Donkey Kong

 

-Ian