[Coco] Re: New CoCo 3 - RF Out problem

[Zippster]

Hi Chad,

As Rogelio was saying, check the 8v supply to the RF.

The fact that composite out is working tells me that the Q3 EF circuit is working.
The output is split off right after that to both the RF box and another EF to the
composite out jack.

The output from Q3 is AC coupled via C67 into the RF box.  I’d check to make sure
that cap (an electrolytic) is good, and that the video signal is making it into the box.
The only things I see in the modulator that might have gone bad are a couple of small
electrolytics, and a couple of transistors(less likely).

Do you have a scope?  Definitely entering territory where one would help here.

- Ed


> On Oct 25, 2015, at 6:46 PM, chadbh74 <chadbh74 at hotmail.com> wrote:
> 
>   It's a 26-3334
> 
>   -Chad
> 
>   https://sites.google.com/site/cbhlab101/
> 
>   Sent from my Galaxy S4
> 
>   --------- Original Message ---------
>   From: Al Hartman
>   To: CoCoList for Color Computer Enthusiasts
>   Date: Sun Oct 25 18:26:52 CDT 2015
>   Subject: Re: [Coco] New CoCo 3 - RF Out problem
>   What's the catalog number on the unit?
>   Could it be a PAL Coco 3?
>   -[ Al ]-
>   -----Original Message-----
>   From: Chad H
>   Sent: Sunday, October 25, 2015 6:23 PM
>   To: 'CoCoList for Color Computer Enthusiasts'
>   Subject: [Coco] New CoCo 3 - RF Out problem
>   I FINALLY acquired a CoCo 3 that was in uncertain condition. He said
>   the
>   last time it was used years ago it worked fine though. It was still
>   sealed
>   appears to be the base 128K setup. The first thing I did was switch my
>   RF
>   cable from my CoCo 2 to the CoCo 3 and power up...click but nothing
>   else. I
>   pressed the RESET button and could hear the relay click, but snowy
>   picture
>   on the old TV. Switched the RF 3/4 switch a few times and nothing. Put
>   the
>   cable back to the CoCo 2 and its perfect image again.
>   I then took the unit to another TV that had a front hookup for RCA Line
>   IN
>   and hooked it up that way. The expected startup message comes right up,
>   nice and clean.
>   Anyone have idea what could be going on here? Simple fix I hope. I
>   could
>   still use it in Line IN mode but I would rather have the CoCo FULLY
>   functional if possible.
>   - Chad H
>   http://sites.google.com/site/cbhlab101/
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