[Coco] Coco 2 RF

[Luis Fernández]

I have it direct, Japanese to coaccial jack, there are also adapters
but it is only + with + and - to -, try it 


> To: coco at maltedmedia.com

> From: haywire666 at aol.com

> Date: Tue, 14 Feb 2012 22:53:09 -0500

> Subject: Re: [Coco] Coco 2 RF

> 

> 

> All this talk about coco2 rf reminded me... I have 3 coco 2's I never or rarely use because the rf is pretty bad.

> 

> 

> Dosn't someone have a circuit for coco2 (someone shared one on coco3.com but it only works on coco1)

> To produce video and audio signals? I'd like to mod my coco2's with a couple of rca jacks in the back with 

> audio and video outputs if possible...

> 

> Steven

> 

> 

> -----Original Message-----

> From: gene heskett <gheskett at wdtv.com>

> To: coco <coco at maltedmedia.com>

> Sent: Tue, Feb 14, 2012 7:30 pm

> Subject: Re: [Coco] Coco 2 RF

> 

> 

> On Tuesday, February 14, 2012 07:02:53 PM Jeremy Michea did opine:

> 

> > “As for your problem, I have never seen it, but since I am a CET, my

> > best guess would be a dried out capacitor in your coco's video

> > circuitry, causing the modulation to be much less than the 90% or so it

> > was designed for, which in turn gives a very low contrast, and likely

> > hard to sync to, image on a tv.â€‌

> > 

> > Thanks Gene. That was kind of what I was looking for. I guess I still

> > wasn’t wording the question properly as some assumed I didn’t know

> > if Composite was simply better. It was more of wondering if it was

> > simply a matter of the poor RF or if there was a deeper issue. For the

> > record, I’m more than aware that composite is better quality than RF.

> > I didn’t fall off the coco turnip truck yesterday

> > 

> > Sadly though I don’t have an oscilloscope. Assuming the problem is the

> > one you describe would it simply be a matter of desoldering the old

> > capacitor and soldering in a new one? Unfortunately I don’t have the

> > soldering skills. I’ve never done it before although I have been

> > wanting to learn, just not enough hours in the day at the moment.

> > Thanks Gene for the answer though I appreciate it.

> 

> You could just form the leads of a somewhere near the same sized 

> cap(acitor), and paying attention to the polarity markings on both, connect 

> the test cap across the likely suspect and check the tv to see if it helps.  

> Don't be surprised if it still helps after the test cap has been removed.  

> What has happened in that event is the that the charging currents from one 

> cap to the other, have caused a momentary nano-weld between the foil of the 

> suspected cap and its lead where they are connected internally.  It won't 

> last long, sometimes only minutes, but that is the response that nails that 

> particular perp to the guilty list.

> 

> Bear in mind also that safe to use around electronics type soldering tools 

> are not the shacks strongest suites, it s/b temperature controlled (most 

> get several hundred degrees too hot if left turned on for 20 minutes) and 

> should have a 3 wire line cord, claiming a static grounded tip.  My fav 

> iron is sold by GC and their ilk for around $150 these days, and has a 

> meter reading in real temps as measured by a platinum sensor touching the 

> back end of the tip insert, and a dial knob to set the temp with, which it 

> will then hold within 10F or thereabouts.  It isn't the greatest iron, but 

> I've had it for going on 25 years and it still works great after probably 

> 10,000 hours of on time.  It, or duplicates of it, have earned me close to 

> a million spread over the last 30 years while I was keeping a tv station on 

> the air.

> 

> When tracing the schematic looking for likely suspects, keep in mind that 

> the cap(s) I am thinking of would be somewhere in the path that could 

> effect the rf output, but not the composite, so that should narrow the 

> search to just 4 or 5 of the 80 or so caps in a coco.  Further narrowing by 

> eliminating anything that is not an electrolytic type should get you down 

> to 2 at most, and likely only one.

> 

> HTH, Jeremy.

> 

> Cheers, Gene

> -- 

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