Colecovision power switch - how does it cause such varied problems?

[freewheel]

Picked up another console recently where the guy said "it kinda-sorta works, maybe you can figure it out". It included the 2 rarest Xonox double-enders and about 20 other games for $100 total, so as far as I was concerned I was already far ahead on the deal, so what the hell. I never EVER find the "rarest" games for any system outside of Ebay or cons, so how could I go wrong?

 

Initial testing really made me think bad caps. I'd get a signal, which quickly faded into junk and eventually just TV static. Sliding the power switch around a lot helped, eventually I got it to the point where I could at least consistently get the title screen - with really bad colors and generally some garbled text, text which got worse with every passing second (think random ASCII eventually). Had me thinking shit, maybe the CPU itself is flaky. But I've heard one of the most common problems is the power switch, so what the heck, let's give 'er a good isopropyl cleaning. A lot of work on the switch later and bam! Good color logo, and games with the occasional graphics glitch but for the most part it's back to 95%. I bet opening the switch for deeper cleaning (or better, replacing) will get it to 100%. No damage to the controller chips which is what I usually see on these things.

 

So I'm curious - how exactly is it that a flaky power switch can cause so many symptoms? From what looks like no power, to maybe failing caps, to graphical glitches and color issues. It really felt that almost anything could be going wrong. Is it due to the weird power connections in the Colecovision? Like say I'm getting fairly clean +12, but the -5 rail is weak or non-existent? Or something like that? Is the electrical system that complicated that it can fail in such spectacularly weird ways? I've never traced what goes where so I've never really considered how each component is powered.

[ColecoDan]

Picked up another console recently where the guy said "it kinda-sorta works, maybe you can figure it out". It included the 2 rarest Xonox double-enders and about 20 other games for $100 total, so as far as I was concerned I was already far ahead on the deal, so what the hell. I never EVER find the "rarest" games for any system outside of Ebay or cons, so how could I go wrong?

 

Initial testing really made me think bad caps. I'd get a signal, which quickly faded into junk and eventually just TV static. Sliding the power switch around a lot helped, eventually I got it to the point where I could at least consistently get the title screen - with really bad colors and generally some garbled text, text which got worse with every passing second (think random ASCII eventually). Had me thinking shit, maybe the CPU itself is flaky. But I've heard one of the most common problems is the power switch, so what the heck, let's give 'er a good isopropyl cleaning. A lot of work on the switch later and bam! Good color logo, and games with the occasional graphics glitch but for the most part it's back to 95%. I bet opening the switch for deeper cleaning (or better, replacing) will get it to 100%. No damage to the controller chips which is what I usually see on these things.

 

So I'm curious - how exactly is it that a flaky power switch can cause so many symptoms? From what looks like no power, to maybe failing caps, to graphical glitches and color issues. It really felt that almost anything could be going wrong. Is it due to the weird power connections in the Colecovision? Like say I'm getting fairly clean +12, but the -5 rail is weak or non-existent? Or something like that? Is the electrical system that complicated that it can fail in such spectacularly weird ways? I've never traced what goes where so I've never really considered how each component is powered.

If the -5 is weak then that means some games won't work as well as the one you got to work. It all depends on the game. Get a new brick or fix yours and your other 5% will be fixed

[NIAD]

You need to properly refurbish the Power Switch and repack with dielectric grease. See the pinned thread titled "Colecovision & Adam Info" and scroll down to Hardware refurb, repair and modifications. Under this title is a DIY thread and post #6 by Harvey deKleine covers the complete power switch refurb.

 

Using alcohol to clean the switch is a temp quick fix, but without repacking with dielectric grease, the problems will persist and continue to get worse.

Edited September 20, 2014 by NIAD

[shadow460]

Just an educated guess here, but I think it causes the voltage supplied to the motherboard to fluctuate. I cleaned mine up with alcohol but I still had problems with the system. Recently I hard wired the power supply and every single problem I had with the system vanished into thin air.

I need to route the power supply wiring back to an external port so I can modify and use a Roller Controller and possibly power Expansion Module #2 from it. That'll be an easy task.

[NIAD]

Something like this mod done by Yurkie....

 

[shadow460]

Probably. I'll figure it out.