Help with ColecoVision 5v

[cfredbandeira]

 

I have a problem. The image of my colecovision was completely fuzzy. I made the change to 5v memory chips. The procedure itself went well. Everything was ok, according to the instructions on the Console5 website. But I still have a fuzzy picture. Measuring the voltage, I realized that the new memory chips are not reaching 5v. The measurement shows about 4.2v. Could you give me an idea of how to get the 5v on the memory chips? Is it possible that the problem is elsewhere on the console? Any idea? The power source is ok. Their voltages are perfect.

[+evg2000]

have you rebuilt the power switch?

It's possible that without load the voltages are fine, but under load they drop - could be the power supply or the switch being dirty.

 

that's all I've got

[cfredbandeira]

 

The power supply has been completely redone and has correct voltages. My other ColecoVision - I have two - works perfectly with it. The power switch was also replaced by a new one.

 

 

As the other ColecoVision works perfectly with this power supply, I believe that there is a voltage drop after the switch is turned on. I replaced the switch, but the problem persists. I would be very grateful to someone who could give me an idea of what to do.

[Bobby Nelson]

So the picture was fuzzy before any mods were done, and it’s still fuzzy? Are you using the original RF output or are you using a composite (or other) AV mod?

Edited April 2, 2020 by Bobby Nelson

[cfredbandeira]

 

The image was confused before any mod. Even using the original RF output. So, first I changed the power switch. Nothing improved. I installed an AV MOD based on the LM318. The image now is very clear, but still fuzzy... finally, I made the 5v memory mod. Nothingh changes. But I noticed after that that there was a voltage drop from 5v to 4.2v. Remembering that this power supply works perfectly on my other ColecoVision. Whenever I turn on the console the voltages drop. 12v to 11v and 5v to 4.2v.

[ChildOfCv]

You need to see how far back the voltage drop goes.  Is it only after the switch?  Before the switch?  At the power plug?

 

For instance, a dirty plug would do it.  A weak rivet connecting the 5V wire to its pin would also cause voltage problems.

[cfredbandeira]

 

 

I noticed this voltage drop on the capacitor C48. C48 is very close to the power switch and the 5v connection. The drop appears in other points, but I found it more interesting to be in this component so close to the 5v power input point on pcb.

[ChildOfCv]

That's before the switch, so it's probably at the power plug too.

[cfredbandeira]

 

I will check this out later today. Any further ideas, I will be very grateful ...

[Bobby Nelson]

My power supplies (for basically any console) measure voltages higher than what is spec'd. A 10 volt supply will measure 12-13 volts when it isn't under a load. I'm not an electrical engineer or anything but if your supply is measuring the exact correct voltages when no load is applied then it might be dropping...but if the voltages were too low I'd think the system just wouldn't work at all. I can't see how a slightly lower voltage would only introduce noise/fuzz into the video signal and nothing more.

 

  But as you said, this power supply works with another colecovision so that's a tricky one! Maybe post a picture of what the screen looks like so we can get a visual representation of this?